DIY Troubleshooting

No heat at all

Nothing comes on, or the air never warms up

1. Check the thermostat. Make sure it is set to HEAT, with the temperature set a few degrees above what the room is now. If the screen is blank or faded, replace the batteries. Worth knowing: If your thermostat takes batteries, change them once a year, before the heating season, so they never run out in a cold snap.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Check the furnace breaker. At your electrical panel, find the breaker for the furnace. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
4. Check the furnace power switch. On or near the furnace there is a switch that looks like an ordinary light switch. It is easy to turn off by mistake. Make sure it is ON. Worth knowing: A small label on that switch, such as “Furnace — leave on”, keeps it from being switched off by mistake again.
5. Make sure the front panel is closed. The front panel on the furnace or indoor unit presses a safety switch, and the system will not run if the panel is loose or off. If it looks crooked, press it firmly into place. Do not remove it or open anything else. Worth knowing: After changing a filter, check the front panel is pushed fully home. A loose one stops the system.
6. Check the gas supply. Make sure your other gas appliances work, such as the water heater or the stove. On the gas pipe to the furnace, the valve handle should run in line with the pipe. If it sits across the pipe, the gas is off; if you do not know why it was turned off, leave it and call us. On propane, check the tank gauge. If you smell gas, stop: see what to do. Worth knowing: If you are on propane, keep an eye on the tank gauge through the winter so it never runs low in a cold spell.
7. Check the condensate drain. If your furnace has white plastic vent pipes, it is a high-efficiency furnace, and it makes water. Check the small drain tube from the furnace is not kinked, disconnected or blocked. If it drains into a small pump, make sure the pump is plugged in and not full. A blocked drain shuts the furnace off. (If your furnace has a metal flue, skip this one.) Worth knowing: A seasonal maintenance visit includes clearing the condensate drain, which keeps this from coming back.
8. Check the vent pipes outside. A high-efficiency furnace has two plastic pipes that run outside through a wall or the roof. Snow, leaves or a bird’s nest over either opening will stop the furnace before it lights. Clear anything you can safely reach by hand, and do not push anything into the pipes. (If your furnace has a metal flue, skip this one.) Worth knowing: After heavy snow or a windy fall, check that both vent pipes outside are clear.
9. Note any flashing light. Many furnaces have a small window in the front panel where you can see a light on the control board. If it is blinking, count the pattern, for example three flashes and a pause. You do not need to open anything. Tell us the pattern when you call: it often means the technician arrives with the right part already on the truck.

Still not working? Call us at (423) 357-1922. No heat in freezing weather? Emergency service is available outside business hours. What it may be: a dirty flame sensor; a failed igniter; the pressure switch or inducer motor; the high limit tripping on poor airflow. Read the full guide.

Blowing cold air

The fan runs, but the air is not warm

1. Check the thermostat mode and fan. It should be on HEAT, set a few degrees above the room temperature, with the fan on AUTO. With the fan set to ON, the blower keeps running between heating cycles and moves air that has not been heated, which feels cold. Worth knowing: Leave the fan on AUTO in winter. The blower then runs only when there is warm air to deliver.
2. Give it five minutes. A furnace runs a short start-up routine before the burners light, and the blower waits until there is heat to deliver. After any change at the thermostat, give it five minutes before deciding it is not working. Worth knowing: A short pause between the thermostat clicking and warm air arriving is normal for a furnace.
3. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
4. Check the gas supply. Make sure your other gas appliances work, such as the water heater or the stove. On the gas pipe to the furnace, the valve handle should run in line with the pipe. If it sits across the pipe, the gas is off; if you do not know why it was turned off, leave it and call us. On propane, check the tank gauge. If you smell gas, stop: see what to do. Worth knowing: If you are on propane, keep an eye on the tank gauge through the winter so it never runs low in a cold spell.
5. Check the condensate drain. If your furnace has white plastic vent pipes, it is a high-efficiency furnace, and it makes water. Check the small drain tube from the furnace is not kinked, disconnected or blocked. If it drains into a small pump, make sure the pump is plugged in and not full. A blocked drain shuts the furnace off. (If your furnace has a metal flue, skip this one.) Worth knowing: A seasonal maintenance visit includes clearing the condensate drain, which keeps this from coming back.
6. Check the vent pipes outside. A high-efficiency furnace has two plastic pipes that run outside through a wall or the roof. Snow, leaves or a bird’s nest over either opening will stop the furnace before it lights. Clear anything you can safely reach by hand, and do not push anything into the pipes. (If your furnace has a metal flue, skip this one.) Worth knowing: After heavy snow or a windy fall, check that both vent pipes outside are clear.
7. Note any flashing light. Many furnaces have a small window in the front panel where you can see a light on the control board. If it is blinking, count the pattern, for example three flashes and a pause. You do not need to open anything. Tell us the pattern when you call: it often means the technician arrives with the right part already on the truck.

Still not working? Call us at (423) 357-1922. No heat in freezing weather? Emergency service is available outside business hours. What it may be: a failed igniter; a dirty flame sensor; the pressure switch or inducer motor. Read the full guide.

Starts, then shuts off

Runs a minute or two, then quits and tries again

1. Check the air filter. Switch the furnace off at the thermostat and slide the filter out. A blocked filter lets the furnace overheat, and a safety switch then shuts the burners off until it cools. That is the most common reason a furnace starts and then quits. If the filter is gray or dusty, replace it and switch back on. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
3. Check the condensate drain. If your furnace has white plastic vent pipes, it is a high-efficiency furnace, and it makes water. Check the small drain tube from the furnace is not kinked, disconnected or blocked. If it drains into a small pump, make sure the pump is plugged in and not full. A blocked drain shuts the furnace off. (If your furnace has a metal flue, skip this one.) Worth knowing: A seasonal maintenance visit includes clearing the condensate drain, which keeps this from coming back.
4. Check the vent pipes outside. A high-efficiency furnace has two plastic pipes that run outside through a wall or the roof. Snow, leaves or a bird’s nest over either opening will stop the furnace before it lights. Clear anything you can safely reach by hand, and do not push anything into the pipes. (If your furnace has a metal flue, skip this one.) Worth knowing: After heavy snow or a windy fall, check that both vent pipes outside are clear.
5. Note any flashing light. Many furnaces have a small window in the front panel where you can see a light on the control board. If it is blinking, count the pattern, for example three flashes and a pause. You do not need to open anything. Tell us the pattern when you call: it often means the technician arrives with the right part already on the truck.

Still not working? Call us at (423) 357-1922. Do not leave it cycling for days. A furnace that keeps overheating stresses the heat exchanger. What it may be: the high limit tripping on poor airflow; a dirty flame sensor; the pressure switch or inducer motor. Read the full guide.

Weak airflow from the vents

Air trickles out, or some rooms get none

1. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.

Still not working? Call us at (423) 357-1922. What it may be: restricted airflow inside the ductwork; a failing blower.

Dusty smell when the heat comes on

Usually the first few runs of the season

1. Is this the first few runs of the season? Dust settles on a furnace over the summer and burns off the first few times the heat runs. That smell should clear within an hour or so.
   • Yes, and it is fading: That is dust burning off. It is normal on the first runs of the season and should clear within the hour.
   • It is not fading, or it smells sharp or electrical: Stop: see what to do.

Water around the furnace

A puddle or a drip near the unit

1. Check the condensate drain. If your furnace has white plastic vent pipes, it is a high-efficiency furnace, and it makes water. Check the small drain tube from the furnace is not kinked, disconnected or blocked. If it drains into a small pump, make sure the pump is plugged in and not full. A blocked drain shuts the furnace off. (If your furnace has a metal flue, skip this one.) Worth knowing: A seasonal maintenance visit includes clearing the condensate drain, which keeps this from coming back.
2. Check the humidifier, if you have one. Some furnaces have a whole-house humidifier on the ductwork: a small box with a thin water line running to it. Look whether the water is coming from there.
   • It is coming from the humidifier: Call us. Turn the humidifier control to OFF while you wait, and keep the water away from anything electrical.
   • No humidifier, or the water is not from there: Carry on to the next check.

Still not working? Call us at (423) 357-1922. Put down a towel or bucket, keep the water away from anything electrical, and switch the system off at the thermostat if water is reaching a floor or ceiling.

Whistling or rattling

Air noise, or something loose

1. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
3. Make sure the front panel is closed. The front panel on the furnace or indoor unit presses a safety switch, and the system will not run if the panel is loose or off. If it looks crooked, press it firmly into place. Do not remove it or open anything else. Worth knowing: After changing a filter, check the front panel is pushed fully home. A loose one stops the system.

Still not working? Call us at (423) 357-1922. If it is grinding, screeching or banging, switch the system off at the thermostat until it has been looked at.

Banging, grinding or screeching

A bang when it lights, or a harsh mechanical noise

1. Switch the heat off at the thermostat. A loud bang when the burners light, or grinding, scraping or screeching from inside the furnace, is not something to leave running. Switch the heat off at the thermostat and leave it off until it has been looked at.

Then: Call us at (423) 357-1922.

Not heating

The house is getting colder

1. Check the thermostat. Make sure it is set to HEAT, not EMERGENCY HEAT, with the temperature a few degrees above the room. Emergency heat locks the heat pump out and runs only the backup heat. Replace the batteries if the screen is blank or faded. Worth knowing: Save emergency heat for when the heat pump has failed. It keeps you warm, but it costs far more to run.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
4. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
5. Check the outdoor disconnect. On the wall next to the outdoor unit is a small box: the disconnect. If it has a handle or switch on the outside, make sure it is set to ON. Leave the box itself closed. Worth knowing: Yard work is the usual way a disconnect gets knocked off, so it is worth a glance afterward.
6. Clear snow and ice from around the unit. Clear snow, leaves and drifted ice from around and on top of the outdoor unit, and make sure it is not sitting in standing water. Never chip at ice with anything sharp. The coil fins puncture easily, and that turns a repair into a replacement. Worth knowing: After heavy snow, clear around the outdoor unit and keep the ground underneath it free to drain.

Still not working? Call us at (423) 357-1922. If the house is getting cold while you wait, switch the thermostat to EMERGENCY HEAT. It runs the backup heat on its own: a way to stay warm until we arrive, not a setting to leave on. What it may be: a failed defrost cycle; a stuck reversing valve; low refrigerant charge. Read the full guide.

Blowing cool air

The air from the vents feels cool

1. Is the house keeping up? Heat pump air is cooler than furnace air, often around body temperature, so it can feel cool against your hand while it heats the house perfectly well. Watch the thermostat for half an hour.
   • Yes, it is holding temperature: That is normal for a heat pump. Nothing is wrong. A heat pump delivers gentler heat over longer cycles than a furnace, so the air feels cooler while the house stays warm.
   • No, the house is getting colder: Carry on to the next check.
2. Check the thermostat. Make sure it is set to HEAT, not EMERGENCY HEAT, with the temperature a few degrees above the room. Emergency heat locks the heat pump out and runs only the backup heat. Replace the batteries if the screen is blank or faded. Worth knowing: Save emergency heat for when the heat pump has failed. It keeps you warm, but it costs far more to run.
3. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
4. Clear snow and ice from around the unit. Clear snow, leaves and drifted ice from around and on top of the outdoor unit, and make sure it is not sitting in standing water. Never chip at ice with anything sharp. The coil fins puncture easily, and that turns a repair into a replacement. Worth knowing: After heavy snow, clear around the outdoor unit and keep the ground underneath it free to drain.

Still not working? Call us at (423) 357-1922. If the house is getting cold while you wait, switch the thermostat to EMERGENCY HEAT. It runs the backup heat on its own: a way to stay warm until we arrive, not a setting to leave on. What it may be: a stuck reversing valve; a failed defrost cycle; low refrigerant charge. Read the full guide.

Outdoor unit iced over

Frost, ice or steam outside

1. What does the outdoor unit look like? In cold, damp weather a heat pump frosts over, and every so often it reverses for a few minutes to melt the frost off. Steam and a whooshing sound during that time are normal.
   • Frost that clears every so often: That is the defrost cycle working. The frost and the steam are normal. Each defrost should last a few minutes before the unit goes back to heating.
   • Solid ice that does not clear: Carry on to the next check.
2. Clear snow and ice from around the unit. Clear snow, leaves and drifted ice from around and on top of the outdoor unit, and make sure it is not sitting in standing water. Never chip at ice with anything sharp. The coil fins puncture easily, and that turns a repair into a replacement. Worth knowing: After heavy snow, clear around the outdoor unit and keep the ground underneath it free to drain.

Still not working? Call us at (423) 357-1922. If the house is getting cold while you wait, switch the thermostat to EMERGENCY HEAT. It runs the backup heat on its own: a way to stay warm until we arrive, not a setting to leave on. What it may be: a failed defrost cycle; low refrigerant charge. Read the full guide.

Runs nonstop, or the bill jumped

The backup heat may be doing the work

1. Check the thermostat. Make sure it is set to HEAT, not EMERGENCY HEAT, with the temperature a few degrees above the room. Emergency heat locks the heat pump out and runs only the backup heat. Replace the batteries if the screen is blank or faded. Worth knowing: Save emergency heat for when the heat pump has failed. It keeps you warm, but it costs far more to run.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Clear snow and ice from around the unit. Clear snow, leaves and drifted ice from around and on top of the outdoor unit, and make sure it is not sitting in standing water. Never chip at ice with anything sharp. The coil fins puncture easily, and that turns a repair into a replacement. Worth knowing: After heavy snow, clear around the outdoor unit and keep the ground underneath it free to drain.
4. Watch for AUX on the thermostat. Many thermostats show AUX or AUX HEAT while the backup electric heat is running. In a hard freeze that is normal for spells. If it is on nearly all the time in milder weather, the heat pump is not keeping up and the backup is carrying the load.
   • AUX is on most of the time: Carry on to the next check.
   • Only now and then, or I cannot tell: Carry on to the next check.

Still not working? Call us at (423) 357-1922. It is worth calling promptly. The house stays warm on backup heat, but it is expensive to leave running. What it may be: auxiliary heat running constantly; low refrigerant charge. Read the full guide.

Not cooling

Runs, but the house stays warm

1. Check the thermostat. Set it to COOL, a few degrees below the room temperature, with the fan on AUTO rather than ON. With the fan set to ON, the blower runs between cycles too, which can make a working system feel like a broken one. Replace the batteries if the screen is blank or faded. Worth knowing: If your thermostat takes batteries, change them once a year so they never run out in the middle of a heat wave.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
4. Check the outdoor disconnect. On the wall next to the outdoor unit is a small box: the disconnect. If it has a handle or switch on the outside, make sure it is set to ON. Leave the box itself closed. Worth knowing: Yard work is the usual way a disconnect gets knocked off, so it is worth a glance afterward.
5. Clear around the outdoor unit. Pull leaves, grass clippings and weeds away from the outdoor unit, cut shrubs back at least two feet, and lift off anything lying on top. Do not reach inside the unit or take any panels off. Worth knowing: Keep two feet clear around the outdoor unit. A gentle rinse of the fins with a garden hose in spring helps, with the power off at the disconnect first. Never use a pressure washer: bent fins make the problem worse.
6. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
7. Feel the air from a vent. With the thermostat on COOL, hold your hand at a supply vent for a minute.
   • It is warm, as if it were heating: Call us. That usually points to the reversing valve, the part that switches a heat pump between heating and cooling. It needs a technician, but it is a well-understood fault.
   • It is cool, just not cool enough: Carry on to the next check.
8. Look for ice. Check the copper pipes where they enter the outdoor unit and, if you can see it without opening anything, the indoor unit. Is there frost or ice on them?
   • No ice: Carry on to the next check.
   • I found ice: Call us. Switch cooling OFF and set the fan to ON to thaw it while you wait. Running an iced system is how a repairable fault becomes a compressor replacement.
9. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.

Still not working? Call us at (423) 357-1922. Cooling out in a heat wave? Emergency service is available outside business hours. What it may be: a stuck reversing valve; low refrigerant from a leak; a failed capacitor; dirty coils. Read the full guide.

Weak airflow from the vents

Air trickles out, or some rooms get none

1. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
3. Look for ice. Check the copper pipes where they enter the outdoor unit and, if you can see it without opening anything, the indoor unit. Is there frost or ice on them?
   • No ice: Carry on to the next check.
   • I found ice: Call us. Switch cooling OFF and set the fan to ON to thaw it while you wait. Running an iced system is how a repairable fault becomes a compressor replacement.

Still not working? Call us at (423) 357-1922. What it may be: restricted airflow inside the ductwork; a dirty indoor coil.

Water leaking indoors

Around the indoor unit, or through a ceiling

1. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.
2. Check the air filter. With the system off, slide the filter out. A blocked filter cuts the air over the indoor coil until it drops below freezing, and the ice then drips as it melts. If the filter is gray or dusty, replace it. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.

Still not working? Call us at (423) 357-1922. Put down a towel or bucket, keep the water away from anything electrical, and switch the system off at the thermostat if water is reaching a floor or ceiling.

Strange noise

Whooshing, rattling or grinding

1. What does it sound like? In cold weather a heat pump makes a loud whoosh when it starts and finishes a defrost cycle, often with steam rising from the outdoor unit. That is normal.
   • A whoosh, then steam, in cold weather: That is a normal defrost cycle. The whoosh is the heat pump reversing to melt frost off its outdoor coil. It should last a few minutes and then go back to heating.
   • Something else: Carry on to the next check.
2. Clear around the outdoor unit. Pull leaves, grass clippings and weeds away from the outdoor unit, cut shrubs back at least two feet, and lift off anything lying on top. Do not reach inside the unit or take any panels off. Worth knowing: Keep two feet clear around the outdoor unit. A gentle rinse of the fins with a garden hose in spring helps, with the power off at the disconnect first. Never use a pressure washer: bent fins make the problem worse.
3. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
4. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.

Still not working? Call us at (423) 357-1922. If it is grinding, screeching or banging, switch the system off at the thermostat until it has been looked at.

Runs, but will not cool

Air moves, but the house stays warm

1. Check the thermostat. Set it to COOL, a few degrees below the room temperature, with the fan on AUTO rather than ON. With the fan set to ON, the blower runs between cycles too, which can make a working system feel like a broken one. Replace the batteries if the screen is blank or faded. Worth knowing: If your thermostat takes batteries, change them once a year so they never run out in the middle of a heat wave.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
4. Check the outdoor disconnect. On the wall next to the outdoor unit is a small box: the disconnect. If it has a handle or switch on the outside, make sure it is set to ON. Leave the box itself closed. Worth knowing: Yard work is the usual way a disconnect gets knocked off, so it is worth a glance afterward.
5. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
6. Clear around the outdoor unit. Pull leaves, grass clippings and weeds away from the outdoor unit, cut shrubs back at least two feet, and lift off anything lying on top. Do not reach inside the unit or take any panels off. Worth knowing: Keep two feet clear around the outdoor unit. A gentle rinse of the fins with a garden hose in spring helps, with the power off at the disconnect first. Never use a pressure washer: bent fins make the problem worse.
7. Look for ice. Check the copper pipes where they enter the outdoor unit and, if you can see it without opening anything, the indoor unit. Is there frost or ice on them?
   • No ice: Carry on to the next check.
   • I found ice: Call us. Switch cooling OFF and set the fan to ON to thaw it while you wait. Running an iced system is how a repairable fault becomes a compressor replacement.
8. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.

Still not working? Call us at (423) 357-1922. Cooling out in a heat wave? Emergency service is available outside business hours. What it may be: low refrigerant from a leak; a dirty condenser or evaporator coil; a failed capacitor; a failing compressor; restricted airflow inside the ductwork. Read the full guide.

Will not turn on

Nothing happens at all

1. Check the thermostat. Set it to COOL, a few degrees below the room temperature, with the fan on AUTO rather than ON. With the fan set to ON, the blower runs between cycles too, which can make a working system feel like a broken one. Replace the batteries if the screen is blank or faded. Worth knowing: If your thermostat takes batteries, change them once a year so they never run out in the middle of a heat wave.
2. Give it five minutes. Many thermostats and outdoor units wait a few minutes before starting again after they shut off, to protect the compressor. After any change at the thermostat, give it five minutes. Worth knowing: That short delay after a change at the thermostat is normal. It protects the compressor.
3. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
4. Check the indoor unit’s power switch. The indoor unit, your furnace or air handler, usually has its own power switch that looks like an ordinary light switch. The air conditioner will not run without it either. Make sure it is ON. Worth knowing: A small label on that switch keeps it from being switched off by mistake again.
5. Make sure the front panel is closed. The front panel on the furnace or indoor unit presses a safety switch, and the system will not run if the panel is loose or off. If it looks crooked, press it firmly into place. Do not remove it or open anything else. Worth knowing: After changing a filter, check the front panel is pushed fully home. A loose one stops the system.
6. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.

Still not working? Call us at (423) 357-1922. Cooling out in a heat wave? Emergency service is available outside business hours. Read the full guide.

Outdoor unit will not run

The fan inside runs; the unit outside does not

1. Check the thermostat. Set it to COOL, a few degrees below the room temperature, with the fan on AUTO rather than ON. With the fan set to ON, the blower runs between cycles too, which can make a working system feel like a broken one. Replace the batteries if the screen is blank or faded. Worth knowing: If your thermostat takes batteries, change them once a year so they never run out in the middle of a heat wave.
2. Give it five minutes. Many thermostats and outdoor units wait a few minutes before starting again after they shut off, to protect the compressor. After any change at the thermostat, give it five minutes. Worth knowing: That short delay after a change at the thermostat is normal. It protects the compressor.
3. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
4. Check the outdoor disconnect. On the wall next to the outdoor unit is a small box: the disconnect. If it has a handle or switch on the outside, make sure it is set to ON. Leave the box itself closed. Worth knowing: Yard work is the usual way a disconnect gets knocked off, so it is worth a glance afterward.
5. Listen at the outdoor unit. With the thermostat calling for cooling, stand beside the outdoor unit for a minute and listen. Do not reach inside it.
   • It hums, but the fan does not turn: Call us. Switch the cooling off at the thermostat while you wait. A hum without the motor starting very often points to a failed capacitor, the most common single part failure there is.
   • It is completely silent: Carry on to the next check.

Still not working? Call us at (423) 357-1922. What it may be: a failed capacitor; a failing compressor. Read the full guide.

Indoor fan will not run

The unit outside runs; the fan inside does not

1. Switch the cooling off for now. Running the outdoor unit without the indoor fan can freeze the coil and, at worst, damage the compressor. Switch cooling off at the thermostat. You can switch it back on briefly to test after each of the next checks.
2. Check both breakers. Most systems have two breakers: one for the indoor unit and one for the outdoor unit. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
3. Check the indoor unit’s power switch. The indoor unit, your furnace or air handler, usually has its own power switch that looks like an ordinary light switch. The air conditioner will not run without it either. Make sure it is ON. Worth knowing: A small label on that switch keeps it from being switched off by mistake again.
4. Make sure the front panel is closed. The front panel on the furnace or indoor unit presses a safety switch, and the system will not run if the panel is loose or off. If it looks crooked, press it firmly into place. Do not remove it or open anything else. Worth knowing: After changing a filter, check the front panel is pushed fully home. A loose one stops the system.

Still not working? Call us at (423) 357-1922. Leave the cooling off until it has been looked at. Running the outdoor unit without indoor airflow can freeze the coil. What it may be: the indoor blower motor; the blower’s capacitor; a control signal not reaching the blower.

Turns on and off a lot

Short runs, many times an hour

1. Look at where the thermostat is. Direct sun, a lamp or TV close by, a drafty door, or a supply vent blowing on it will all make a thermostat read the wrong temperature and switch the system on and off too soon. Close the blinds, move the lamp, or turn the vent away from it. Worth knowing: Keep lamps, TVs and anything warm away from the thermostat, and do not let a supply vent blow on it.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Clear around the outdoor unit. Pull leaves, grass clippings and weeds away from the outdoor unit, cut shrubs back at least two feet, and lift off anything lying on top. Do not reach inside the unit or take any panels off. Worth knowing: Keep two feet clear around the outdoor unit. A gentle rinse of the fins with a garden hose in spring helps, with the power off at the disconnect first. Never use a pressure washer: bent fins make the problem worse.
4. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.

Still not working? Call us at (423) 357-1922. What it may be: an oversized system short-cycling; restricted airflow inside the ductwork.

Cool, but damp and clammy

The temperature is right; the air feels sticky

1. Set the fan to AUTO. With the fan set to ON, the blower keeps running after cooling stops and blows the water on the cold indoor coil back into the house. On AUTO, that water drains away instead. Give it a day on AUTO. Worth knowing: Leave the fan on AUTO in summer. That is how your system removes the most moisture.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.

Still not working? Call us at (423) 357-1922. When the cause is an oversized system, correct sizing is the real fix; a whole-house dehumidifier is the retrofit answer. What it may be: an oversized system short-cycling.

Weak airflow from the vents

Air trickles out, or some rooms get none

1. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
3. Look for ice. Check the copper pipes where they enter the outdoor unit and, if you can see it without opening anything, the indoor unit. Is there frost or ice on them?
   • No ice: Carry on to the next check.
   • I found ice: Call us. Switch cooling OFF and set the fan to ON to thaw it while you wait. Running an iced system is how a repairable fault becomes a compressor replacement.

Still not working? Call us at (423) 357-1922. What it may be: restricted airflow inside the ductwork; a dirty evaporator coil.

Ice on the pipes or coil

Frost on the copper lines or the indoor unit

1. Switch cooling off and the fan on. Set the thermostat to OFF for cooling and the fan to ON. The blower will thaw the ice, which can take a few hours. Do not chip at it. Running an iced system is how a repairable fault becomes a compressor replacement.
2. Check the air filter. With the system off, slide the filter out. A blocked filter cuts the air over the indoor coil until it drops below freezing, and the ice then drips as it melts. If the filter is gray or dusty, replace it.
3. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air.

Then: Call us at (423) 357-1922. Leave cooling off until it has been looked at. What it may be: low refrigerant from a leak; restricted airflow. Read the full guide.

Water leaking indoors

Around the indoor unit, or through a ceiling

1. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.
2. Check the air filter. With the system off, slide the filter out. A blocked filter cuts the air over the indoor coil until it drops below freezing, and the ice then drips as it melts. If the filter is gray or dusty, replace it. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.

Still not working? Call us at (423) 357-1922. Put down a towel or bucket, keep the water away from anything electrical, and switch the system off at the thermostat if water is reaching a floor or ceiling.

Strange noise

Rattling, buzzing or grinding

1. Clear around the outdoor unit. Pull leaves, grass clippings and weeds away from the outdoor unit, cut shrubs back at least two feet, and lift off anything lying on top. Do not reach inside the unit or take any panels off. Worth knowing: Keep two feet clear around the outdoor unit. A gentle rinse of the fins with a garden hose in spring helps, with the power off at the disconnect first. Never use a pressure washer: bent fins make the problem worse.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.

Still not working? Call us at (423) 357-1922. If it is grinding, screeching or banging, switch the system off at the thermostat until it has been looked at.

Screen is blank

Nothing on the display

1. Replace the batteries. Many thermostats run on AA or AAA batteries, behind the front cover or in a slot on the side. Fit fresh ones, even if you think the old ones are fine. (If your thermostat does not take batteries, skip this one.) Worth knowing: Change thermostat batteries once a year. Many people do it when the clocks change.
2. Check the power to the indoor unit. Many thermostats get their power from the furnace or air handler. Check that unit’s breaker at your panel, and the switch on or near the unit that looks like a light switch. Push a tripped breaker firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
3. Make sure the front panel is closed. The front panel on the furnace or indoor unit presses a safety switch, and the system will not run if the panel is loose or off. If it looks crooked, press it firmly into place. Do not remove it or open anything else. Worth knowing: After changing a filter, check the front panel is pushed fully home. A loose one stops the system.
4. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.

Still not working? Call us at (423) 357-1922.

System will not respond

You change the setting and nothing happens

1. Check the mode and the setting. Make sure the thermostat is not set to OFF. It should be on HEAT or COOL, with the temperature set a few degrees past the room temperature so the system has a reason to start. Worth knowing: Whenever the system seems not to respond, check the mode first. It is the quickest check there is.
2. Check the schedule and hold. A programmed schedule can override what you just set. Look for HOLD or a schedule on the screen, then set a temporary hold, or switch the schedule off, to test. Worth knowing: If you use a schedule, look it over when the clocks change and when the season turns.
3. Give it five minutes. Many systems wait a few minutes before starting again after a change, to protect the equipment. Give it five minutes before deciding it is not responding. Worth knowing: A delay of a few minutes after a change at the thermostat is normal.
4. Replace the batteries. Many thermostats run on AA or AAA batteries, behind the front cover or in a slot on the side. Fit fresh ones, even if you think the old ones are fine. (If your thermostat does not take batteries, skip this one.) Worth knowing: Change thermostat batteries once a year. Many people do it when the clocks change.
5. Check the power to the indoor unit. Many thermostats get their power from the furnace or air handler. Check that unit’s breaker at your panel, and the switch on or near the unit that looks like a light switch. Push a tripped breaker firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.

Still not working? Call us at (423) 357-1922.

Fan runs all the time

The blower never stops

1. Check the fan setting. With the fan set to ON, the blower runs all the time, whether or not the system is heating or cooling. Set it to AUTO. Worth knowing: AUTO runs the blower only when it is needed, which is quieter and uses less electricity.
2. Watch one full cycle. After heating or cooling stops, the blower often keeps running for a minute or two to deliver the last of the warm or cool air. Watch it through one full cycle.
   • It stops a minute or two after the cycle: That is normal. The blower runs on briefly after each cycle to use up the heat or cooling already in the system.
   • It never stops: Carry on to the next check.

Still not working? Call us at (423) 357-1922.

Reading looks wrong

The screen says one thing; the room feels another

1. Look at where the thermostat is. Direct sun, a lamp or TV close by, a drafty door, or a supply vent blowing on it will all make a thermostat read the wrong temperature and switch the system on and off too soon. Close the blinds, move the lamp, or turn the vent away from it. Worth knowing: Keep lamps, TVs and anything warm away from the thermostat, and do not let a supply vent blow on it.
2. Replace the batteries. Many thermostats run on AA or AAA batteries, behind the front cover or in a slot on the side. Fit fresh ones, even if you think the old ones are fine. (If your thermostat does not take batteries, skip this one.) Worth knowing: Change thermostat batteries once a year. Many people do it when the clocks change.

Still not working? Call us at (423) 357-1922.

Not heating

Locking out, or the house is getting colder

1. Check the thermostat. Make sure it is on HEAT, not emergency heat or auxiliary heat only, with the temperature a few degrees above the room. Worth knowing: Save emergency heat for when the geothermal unit has failed. It keeps you warm, but it costs far more to run.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
4. Check the breakers. Check the breakers for the geothermal unit and for the loop circulator pumps. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
5. Note any fault code. Look for a fault or lockout code on the unit’s display, or a blinking light you can see without opening anything, and write down what it shows.
6. Read the loop pressure gauge. If your system has a pressure gauge on the loop piping that you can see easily, note the reading. Low loop pressure is the most common geothermal fault. If there is no gauge, leave this blank.
7. Listen for the circulator pumps. When the system is calling for heat or cooling, the pumps that move fluid through the ground loop should be running. Listen near where the loop pipes come into the house for a steady low hum.
   • I can hear them running: Carry on to the next check.
   • They are silent: Carry on to the next check.
   • I am not sure: Carry on to the next check.
8. Check whether the backup heat is doing the work. Many thermostats show AUX or AUX HEAT while the backup electric heat is running. If it is on nearly all the time, the house is being heated by the backup while the geothermal side does little or nothing.
   • AUX is on most of the time: Carry on to the next check.
   • Only now and then, or I cannot tell: Carry on to the next check.

Still not working? Call us at (423) 357-1922. No heat in freezing weather? Emergency service is available outside business hours. What it may be: low loop flow or pressure; a failed circulator pump; a stuck reversing valve; auxiliary heat carrying the load; control or sensor faults. Read the full guide.

Not cooling

Locking out, or the house stays warm

1. Check the thermostat. Set it to COOL, a few degrees below the room temperature, with the fan on AUTO rather than ON. With the fan set to ON, the blower runs between cycles too, which can make a working system feel like a broken one. Replace the batteries if the screen is blank or faded. Worth knowing: If your thermostat takes batteries, change them once a year so they never run out in the middle of a heat wave.
2. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
3. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.
4. Check the breakers. Check the breakers for the geothermal unit and for the loop circulator pumps. A tripped breaker sits in the middle or in the OFF position. Push it firmly to OFF, then back to ON, once only. If it tripped again, stop: see what to do. Worth knowing: A breaker can trip once for no lasting reason. If it trips again, leave it off and call us.
5. Note any fault code. Look for a fault or lockout code on the unit’s display, or a blinking light you can see without opening anything, and write down what it shows.
6. Read the loop pressure gauge. If your system has a pressure gauge on the loop piping that you can see easily, note the reading. Low loop pressure is the most common geothermal fault. If there is no gauge, leave this blank.
7. Listen for the circulator pumps. When the system is calling for heat or cooling, the pumps that move fluid through the ground loop should be running. Listen near where the loop pipes come into the house for a steady low hum.
   • I can hear them running: Carry on to the next check.
   • They are silent: Carry on to the next check.
   • I am not sure: Carry on to the next check.
8. Check the condensate drain. When it cools, your system makes water that runs away through a drain pipe from the indoor unit. If that drain backs up, a float switch shuts the system off to prevent a flood, and on many systems that cuts power to the thermostat too. Look for water standing in the pan under the indoor unit, or a drain line that has come loose.
   • The drain looks fine: Carry on to the next check.
   • Water in the pan, or a blocked drain: Call us. Leave the system off at the thermostat until the drain has been cleared, and put down a towel or bucket if water is reaching the floor.
   • I cannot see one: Carry on to the next check.

Still not working? Call us at (423) 357-1922. Cooling out in a heat wave? Emergency service is available outside business hours. What it may be: low loop flow; a failed circulator pump; a stuck reversing valve; condensate drain blockage; refrigerant charge issues. Read the full guide.

Bill jumped, but the house is warm

The backup heat may be doing the work

1. Check the thermostat. Make sure it is on HEAT, not emergency heat or auxiliary heat only, with the temperature a few degrees above the room. Worth knowing: Save emergency heat for when the geothermal unit has failed. It keeps you warm, but it costs far more to run.
2. Check whether the backup heat is doing the work. Many thermostats show AUX or AUX HEAT while the backup electric heat is running. If it is on nearly all the time, the house is being heated by the backup while the geothermal side does little or nothing.
   • AUX is on most of the time: Carry on to the next check.
   • Only now and then, or I cannot tell: Carry on to the next check.

Still not working? Call us at (423) 357-1922. It is worth calling promptly. Backup electric heat keeps the house warm, but it is expensive to leave running. What it may be: auxiliary heat carrying the load. Read the full guide.

Weak airflow from the vents

Air trickles out, or some rooms get none

1. Check the air filter. Switch the system off at the thermostat, then slide the filter out. It sits behind a return grille or in a slot at the furnace or indoor unit. If it is gray or dusty, or you cannot remember the last change, put in a new one of the same size and switch back on. A blocked filter starves the system of air, and it is behind more of the calls we go out on than anything else here. Worth knowing: Check the filter once a month and change it when it looks gray: more often with pets, or in the months the system works hardest.
2. Open the vents and clear the returns. Walk through the house. Every supply vent should be open, and no furniture, rug or curtain should be covering a return grille: the larger grilles that draw air back to the system. Closed vents and blocked returns starve the system of air. Worth knowing: Leave supply vents open, even in rooms you do not use, and keep furniture a little away from return grilles.

Still not working? Call us at (423) 357-1922. What it may be: restricted airflow inside the ductwork.