Power of Community - Pedernales Electric Cooperative

A reminder for heat pump owners

Dec 22, 2011

EDITOR'S NOTE: Energy Service Advisor Chris Denison has posted an update to this article. Read more »

Chris DenisonA malfunctioning heat pump can cause excessive energy use, and you may not know it until you get your electric bill.

If you have a heat pump set to heat mode, make sure the outside compressor is operating when the indoor air handler is running. If the outside unit is not operating, the auxiliary resistance heat will automatically come on to heat your house; you won’t know the compressor is not operating because the house will be warm.

Check your heat pump's performanceEveryone should be familiar with the Auxiliary Heat (Aux Ht) indicator on their thermostat. The auxiliary heat — which uses resistance heat strips located in the air handler to warm air — will automatically come on to compensate when the heat pump is not creating enough heat on its own. However, it’s a much less efficient way to heat your home, requiring two to three times more energy than a properly operating heat pump by itself.

The auxiliary heat is designed to operate when the indoor temperature is three degrees cooler than the thermostat setting. It generally operates when you raise the thermostat setting more than two degrees, which may be normal when you get up to a cold house in the morning or come home to a cold house in the evening. That is a good time to notice where your auxiliary indicator is and make sure that it goes off when the indoor temperature is within two degrees of your thermostat setting.

If you have a heat pump, it is best to increase your heat setting by only two degrees at a time to prevent your auxiliary heat from operating.

What steps have you taken to conserve energy this winter?

This is a moderated blog, so all comments are reviewed prior to posting. Your e-mail address is required in case we need to contact you about your comment; your e-mail address will not be published. Review our Conservation Blog Guidelines for more information.


  1. 1 Robin 17 Sep
    Thanks to your blog post we were able to figure out something was wrong with our newly (May) installed heat pump.  We called the service and the installers had wired the air handler and the thermostat incorrectly.  Now the outside unit is working when it is suppose to be.   I hope for a lower bill next month.  Thanks.
  2. 2 PEC 17 Sep

    We're glad to hear that the information we provided was helpful, Robyn! Thanks for sharing.

    If you'd like to check your daily electric use before you receive your next bill, you can view your MyUse Energy Analyzer report by signing in to your account online.

    — PEC

  3. 3 plumbing supplies 17 Sep
    You be familiar with the functions of your heat pump. This is to ensure your safety.
  4. 4 Jason 17 Sep
    Please point out that your heat pump may look like it is not working when it is going through its defrost cycle.  This can happen on a regular basis (usually 30, 60 or 90 minute periods) with the right outside conditions.  So while it is true that your machine outside should be running during the winter, if you have a heat pump - there are times when the outdoor unit might not appear to be running when the inside unit is running.  If the Thermostat fan switch is set to "On" rather than "Auto" your indoor unit will run all the time and the outdoor machine will only come on with a call for heating (or cooling - hey this is Texas!)
  5. 5 Trish 17 Sep
    I need to replace my heating and A/C system. I am hoping to get at least a partial solar unit to help. I am older and on a pretty limited budget. Do you have any suggestions for me?

    I spoke to Austin A/C Solar Installation and they wanted to sell me a $30000 system. I can't afford that. Right now I only use heat when it gets below freezing (pipes and birds) and only use A/C is it gets over 95.

    I would love to have a system I could afford to use, especially during the summer. (During the winter my yorkies and I mostly get under the covers and try not to freeze - it works ok. Summer is not so easy.

    Any helpful information would be greatly appreciated
  6. 6 valued customer 17 Sep
    Something else to watch for is the heat pump defrost cycle.  typically the heat pump will go into defrost cycle every 90 minutes of run time in the winter.  some units make a PSSSST noise inside when this happens.  Defrost cycle is where the compressor runs, but the top exhaust fan does not. What this does is put the unit into a sort of AC mode where the heat generated outside melts off any ice or frost on the cooling fins.  There will be a humming noise from the compressor, you will see steam rising and water dripping off the bottom sides.  To compensate for the cold air coming out of the vents inside the air handler heat strips will come on.  The air coming out of the vents will only be luke warm as the heat strips are trying to counter act the cold air being produced.  The defrost cycle typically only runs for a couple of minutes.  If solid ice starts to build up on the air fins outside and the unit never goes into defrost mode, you should call a repair service.  as a temporary fix you can switch the thermostat into AC mode to simulate the defrost mode and melt the ice on the air fins outside.
  7. 7 PEC 17 Sep

    Trish, your comment was forwarded to our energy management team, and one of our specialists will contact you to discuss your specific situation and offer suggestions that may help you save energy and money.

    You also may want to check out some of the other Savings & Conservation resources on our site, including information about our rebate program for HVAC systems.

    — PEC

  8. 8 brandy 01 Nov
    Our inside temp is 65. I set it to 66 and the unit kicks on and starts to blow air through the vents. Within a minute aux heat flashes and a red light comes on. After about 30 seconds the outside unit shuts off and no air/heat is coming through vents.  The red light stays on and unit never attempts to cut on no matter how long is left on.  
  9. 9 PEC 03 Nov

    Brandy, our Energy Services team suggested it's probably time to get an A/C contractor out to check the unit. There are a number of things that could be causing what you're experiencing, and if your auxiliary heat strips are coming on and staying on you are spending more on electricity than you need to.

    — PEC

  10. 10 becky 08 Nov
    I have a heat pump for my house.  I can hear a fan running in the house and warm air is coming from the vents.  My setting on the fan in the house is auto.  But, when I go outside to the unit the fan is not turning.  Does this mean it is not working right.
  11. 11 gary 10 Nov
    Heil 10 series heat pump set at 67°. UNIT WILL RUN ROUGHLYV 18Munutes About 14 minutes aux. heat comes on at least two miinutes then goes off unitvruns couple if mire minutes then shuts off ?
  12. 12 PEC 12 Nov

    Becky, if your outside unit is silent the heat pump is not operating at all, so the auxiliary heat is what’s warming the air coming into your house. Our energy services team said if it continues to heat without the outside unit coming on when the temperature outside is warmer than 30 to 40 degrees, you may need to have it checked by a professional.

    Gary, our energy services team said your heat pump may not be working correctly or it may be low on refrigerant, especially if it behaves the way you describe when the temperature outside is around 50 degrees or warmer.

    — PEC

  13. 13 Bill 23 Nov

    We have a new heat pump and are using heat mode for the first time. When it comes on the air from the vents feels 'cool' not warm, but then warms up. When the outside unit goes off there is still air coming from the vents for between 5 to 10 minutes and if I put my hand on the outside unit, I feel a slight vibration. Sometimes the outside unit cycles on and off while fan is still blowing air from the vents. Is there something wrong here? The house seems to get comfortably warm, and we had no problems while running in A/C mode here in Las Vegas.

  14. 14 PEC 25 Nov

    Bill, Chris Denison said when your heat pump first comes on it has to chase the cool air out of the ducts before warm air reaches the inside of the house. The continuing air flow and slight vibration probably indicate the outside unit is defrosting; if it's close to freezing outside, defrosting is a common operation and you should see an 'Aux' heat indicator on your thermostat while it is occurring.

    Your heat pump will use more electricity to keep your house comfortably warm when the auxiliary heating unit is operating, though. To track the difference try checking your MyUse Energy Analyzer reports. The reports include the high and low temperatures along with your energy use to let you track how colder temperatures impact your use.

    — PEC

  15. 15 Bill 26 Nov

    Thank you, and Mr. Denison for your reply to my questions regarding my new heat pump. it appears to be doing what it is supposed to do I will keep a watch on the aux. heat indicator on my thermostat

    Thank you again for your reply and help.


  16. 16 Karen 30 Dec

    My heat pump never shuts off. The inside temp says 68 and heat setting will say the same, but never shuts off. It always blows cold air through vents, never feels warm. When I go outside and look at fan on top down inside I see iced up coils. Fan is set to auto and temp is set on heat. I always have to cut thermostat back below 68 to get it to shut off. Then my house gets to cold. My thermostat and unit are only 3 years old. Is this normal?

  17. 17 Cecilia 31 Dec

    I live in Florida and have a heat pump, if I place the heat pump in air conditioner mode, the outside fan comes on. if I change it to heat mode the outside fan will not come on, yet the inside unit is still working and heating the house.

  18. 18 PEC 31 Dec

    Karen, Chris Denison said it sounds like your heat pump's defrost cycle is not working properly, which may require a service call by an HVAC professional.


    Cecilia, he said your heat pump is using its auxiliary heat coils to warm air coming into your home, which isn't efficient. If your thermostat has an emergency heat setting it will override normal heat pump operation. If you don't have that option selected, there's a problem with your unit that will require a professional.

    — PEC

  19. 19 chris 01 Jan

    Hello happy New Year. I live in VA. I  have a heat pump unit which was installed a year  ago. I noticed for a while now that when I turn my heat on the furnace is constantly running while the outdoor unit does not come on. My thermasat is set to 70 on automatic and sometimes switches to auxiliary mode. Mostly cool air is blowing from the vents even at 70 degrees and still the outside unit does not come on. Also, my bill is 3 times higher than the summer. Is this a problem?

  20. 20 PEC 02 Jan

    Chris, it typically costs two or tree times as much to heat as it does to cool an all-electric home. However, if your outside unit isn't running at all, even when temperatures are warmer than 30 to 40 degrees, you may need to have it checked by a professional.

    — PEC

  21. 21 Amber 10 Jan
    My aux is always on and when it's below 30 degrees my aux sometimes won't kick on, I have it set to 74 at night and still my house is in the low 60's
  22. 22 PEC 12 Jan

    Our energy services team said you could have a bad thermostat on the outside unit, Amber. They recommend you have the unit serviced by a qualified service technician.

    — PEC

  23. 23 Barbara 20 Jan
    8Heat pump is new. Two different stats installed. First, A/C worked fine, but then no heat come winter. New board installed in unit. Then, when in 20s outside, inside set at 65, temp would drop to 60 with aux heat showing on. Warmed up outside to 50s. Old and new stats, aux heat comes on when temp bumped up from 68 to 69 with inside temp showing 68. What is going on? Functions in stat set for heat pump, no changeover, O wire to O/B, blue wire not used (went to C on old stat, no C on new stat), R & Rc jumped per instructions (wire to R only), white to Aux, etc per instructions. Thank you
  24. 24 John 26 Jan
    Our heat pump seems to be great when the temps are roughly freezing or below, but strangely it's not working well at higher temps like 40's - 50's. It will run and run with no or almost no discernible air coming out the vents until the temp finally gets low enough for aux to kick in. Then whenever the temps drop down into the harsher range, it works perfectly. What do you think could cause this?
  25. 25 PEC 28 Jan

    Barbara, our Energy Services team suggests you ask the contractor who installed your unit to verify it is working properly and to confirm your thermostat was installed correctly. If not, the contractor should honor the warranty on the new unit and fix the problem.


    John, sounds like your auxiliary heat is working but your heat pump is not generating heat on its own. You should have it checked to make sure the coolant is adequately charged.


    — PEC

  26. 26 Marc 16 Feb
    Last night the outside temperature dropped to 2 degrees. I had my thermostat set at 62 degrees. Can a heat pump produce any warm air when outside temp is that cold? My auxiliary heat is not working. Can the outside heat pump keep my house at 62F if the outside temperature is less then 10 degrees?
  27. 27 PEC 16 Feb

    Marc, our Energy Services team said each heat pump has a certain temperature at which the auxiliary heat takes over. Below 10 degrees is most likely way too cold for reliable operation without auxiliary heat. Bundle up and think about scheduling a service call with a reputable A/C contractor.

    — PEC

  28. 28 Brandon 20 Feb
    If I have my unit off all day and cut it on when I get home, the aux will run for a little bit then cut off which I hear is normal. However, the aux will randomly cut on every so often for several minutes then go back off and the normal heat will keep running. Is this just due to 10-25 degree temps outside? Thank you.
  29. 29 chris 20 Feb
    when my heat pump is running my unit tends to blow warm air and when auxiliary heat kicks in it starts blowing cold air for about ten minutes before the air warms up. why does it take so long before unit blows warm air after going into auxiliary mode. 

    Also when my thermostat reaches the temp setting auxiliary heat still runs even if setting and temp is the same.
  30. 30 Jackie 20 Feb
    Hello, my heating pump blows out cold air. I had a tech come out and he said that the refridrant was low and the condenser fan motor needs to be replaced. Should these 2 issues prevent the aux heat from warming the house? 
  31. 31 PEC 24 Feb

    Brandon, Energy Services Representative Chris Denison said if the auxiliary heat comes on during normal heat pump operation, it's an indication there is not enough heat being generated, which usually indicates low coolant levels.


    Chris, the air should be hot immediately when the auxiliary heat is operating, and the auxiliary heat should not be operating when the room temperature is within two degrees of your thermostat setting. You might have an issue with the thermostat controls or the factory default settings in the electronic controls. Probably time to contact a service technician.


    Jackie, low refrigerant or a faulty condenser fan motor should not prevent the auxiliary heat from warming your house. The thermostat may not be responding correctly. Try setting it to "E" or "Em" heat manually for the time being.


    — PEC

  32. 32 Morris 25 Feb

    What can I do to keep my fan from freezing on my heat pump. Has layer of ice on top of fan.

  33. 33 PEC 26 Feb

    Morris, Energy Services Representative Chris Denison said the ice should melt during the defrost cycle. The problem may occur if there is moisture from the roof line or some other source. If that's the case, might try deflecting the moisture away from the unit.

    — PEC

  34. 34 Paula 28 Feb
    Hello!  I think I am having issues with my heat pump.  First, the auxiliary heat kicks on constantly (every five or so minutes) even when it is at the desired temp and the heat pump continues to run. Also, the unit goes into defrost mode (fan stops then swish noise) every 90 or so minutes even when there is no frost on the unit.  After about five minutes, there is a swishing sound but the fan doesn't turn on...then another swish and a very loud noise starts.  It continues for about a half an hour, heating the house (going back and forth between aux and heat pump) then the fan finally kicks back on.  It continues to heat until it goes into defrost mode again and the cycle continues.  Can you offer any guidance?   Thank you!
  35. 35 PEC 02 Mar

    Paula, Chris Denison suggested you check the temperature of the air coming through the supply vents in your home; the air coming out should be at least 20 degrees warmer than the indoor room temperature.

    If it is not, then have a contractor check the coolant level in your air conditioning system. If the problem persists, there may also be an issue with the electronic controls or the factory default setting for the outside defrost temperature limit switch.

    — PEC

  36. 36 Ola 06 Mar
     We have had extremely cold weather and snow during the past week and my heat pump appeared to be working because the  house is warm.  After finally getting out of the house, I noticed the outside unit was covered with snow and ice (except the top) and the fan was not rotating.  What do I do? Should I continue to use my heating unit?
  37. 37 PEC 12 Mar

    Ola, Energy Services Supervisor Joe Paramo said it sounds like the defrost cycle is not sufficiently removing the ice build-up or is not operating at all. He advises that you have an air conditioning contractor service the unit. Right now the unit is probably operating in auxiliary or emergency heat mode to keep your house warm, which uses more electricity than a heat pump operating in normal mode.

    — PEC

  38. 38 Holly 16 Mar

    We just got our last electric bill and I almost had heart failure.  We keep our house at 67 but have notice that when thermostat is above our setting the unit outside will keep running.  I even turned off the unit from the thermostat completely and the unit outside is still running.  There is no heat coming out of vents but the fan continues to run.  What is going on?  The only way to get the outside fan to stop running is turning the circuit breaker off.

  39. 39 PEC 17 Mar

    Holly, Energy Services Supervisor Joe Paramo said it sounds like the contactor, which controls the fan motor on your outside unit, is stuck on. He suggested two possible causes: the thermostat is not sending the signal to the coil to disengage the contactor, or the contactor is permanently engaged due to wear or heat.

    He suggested you call your HVAC contractor. This is something that needs troubleshooting by a licensed air conditioning professional.

    — PEC

  40. 40 McDanel 21 Mar

    Hi, I think I have multiple issues or just one getting progressively worse. During this winter, I have noticed pretty much the Aux Heat is the only thing that heats our house when the heat pump is on. I was blowing multiple fuses daily, then I have taken out the air filter and that fixed the fuse problem. I noticed about a month ago ice build up inside the unit, I thought it was normal due to a lot of snow, but it is still there. Now today, the unit will run but the fan will not, making a loud buzzing. (Wife says it sounds like its going to blow up) haha. Any advice?

  41. 41 PEC 23 Mar

    McDanel, Energy Services Representative Chris Denison said it sounds like your unit's defrost function is not working properly. He recommends you contact a licensed air conditioning professional and ask them to check the control board.

    — PEC

  42. 42 elizabeth 26 Mar

    Heat pump in heat mode at temp 74 but the indoor unit  displays air condition icon alternating with defrost icon.  Is that normal?

  43. 43 PEC 30 Mar

    Elizabeth, Energy Services Representative Chris Denison said you should only see the defrost indicator when outside temperatures are close to freezing, and the defrost function should not occur more often than one an hour, and only that frequently if outside temperatures are well below freezing. To see the indicators you describe during regular heat pump operation is not normal and he suggested you consult your air conditioning contractor.

    — PEC

  44. 44 wayne 01 Apr
    I have a Rudd heat pump with a reset button the inside fan will run with the auxiliary heat but won't run with the outside unit. I push the reset button and the outside unit comes on and the lines get hot but the inside fan don't come on so the outside unit kicks out.
  45. 45 PEC 04 Apr

    Wayne, Energy Services Supervisor Joe Paramo said a problem with the thermostat or the blower time delay relay may be preventing the inside fan motor from coming on, but it will take a visit from an air conditioning professional to troubleshoot the problem.

    — PEC

  46. 46 jd 05 Jun
    My heat pump is set to cool, but auxiliary heat keeps turning itself on
  47. 47 PEC 08 Jun

    JD, our Energy Services team said we see this happen in some cases when members switch from heating to cooling and it's generally caused by a malfunction in the thermostat or the relay that controls the auxiliary heat. They recommend you call a trained air conditioning technician.

    — PEC

  48. 48 Norma 08 Jun

    We have been experiencing very high electric bills.  Not sure what the issue with the heat pump is.  It doesn't seem to ever shut off.  I am currently using the AC.  Thermostat is set at 72 and temp shows 72.  System will run for hours this way.  Usually there is at least 2 or 3 degrees in the temp.  After this began happening, we had a new thermostat installed it has helped some, but system is still running solid for at least two hours at a time.  Any ideas?

  49. 49 PEC 09 Jun

    Norma, Energy Services Representative Brian Curtsinger recommends you have the unit serviced by a qualified air conditioning technician. It could be low on refrigerant, it could be heating and cooling at the same time, it could have a piece if debris in the reversing valve – a number of different things could be happening so best to have it looked at by a professional.

    — PEC

  50. 50 Bill 01 Jul
    Should the outside unit be running when the AD is on?   I have the temp set to 70 and it shows the house at 80 and outside at 90. But my outside compressor is not running so I am not sure it's working properly. 
  51. 51 PEC 07 Jul

    Bill, Energy Services Representative Chris Denison said your outside unit should be running and he suggested you contact an air conditioning contractor.

    — PEC

  52. 52 Dubb 01 Dec

    I just began using my heat about a week ago. I don't leave my heat on during the day and when I get home and cut it on both the AUX and EM heat come on at the same time. I went outside to make sure the outside unit was running and it was and the inside unit was on as well. If it helps any it was 45 degrees last night when I got home at 530pm EST. When the temperature has set itself it will cut off. When it comes back on no lights are showing and the system runs just fine. Should I call someone out to check things out just in case?

  53. 53 PEC 03 Dec

    Dubb, Energy Management Representative Chris Denison said what you're experiencing is normal operation. It may be less expensive to leave it set at a slightly more efficient (cooler) setting during the day, and try not to increase the heat setting by more than 2 degrees at a time when you come home to avoid AUX heat operation.

    — PEC

  54. 54 Michael 24 Dec
    I have had 2 different repair companies 3 different times over the past year. For some reason, when my unit is running in the A/C mode, the auxillary comes on. I was told it was the sequencer in the air handler one time and that it was low on gas another time. It was working fine for about 5 months now, but it is doing it again. We have had this problem over the last 2-3 years, but nobody seems to know what is wrong.
  55. 55 PEC 28 Dec

    Michael, Energy Management Representative Chris Denison said the situation you describe indicates it is definitely a technical issue, probably caused by a faulty sequencer. Without more detailed information – if you are a PEC member we can check your usage to see if it reveals anything – we recommend you contact another contractor.

    — PEC

  56. 56 Brandy 02 Jan
    Hi, I have a heat pump, it wants to run for about 37 minutes every hour just to go up 1 maybe 2 degrees is this normal?
  57. 57 Beth 03 Jan
    My heat pump has been running in Aux for about 8 to 10 days now, and the outside compressor has not come on in that time. It bares noting that the temps where I am have been consistently in the teens, and not gotten above 35 in that time. (Unusual for where I am) Should I be concerned and contact a repair company? Or just wait and see if things improve when the temps warm up again? We are currently also shutting the system totally down and supplementing with space heaters and the fire place.
  58. 58 PEC 04 Jan

    Brandy, Energy Management Representative Brian Curtsinger said what you describe sounds about right for a heat pump, depending on how well your house is insulated and how cold it is outside. Keep in mind the air coming out of the registers should be between 85 and 105 degrees if the system is operating correctly.


    Beth, Brian said usually the compressor should run even when the auxiliary heat is on. He recommended you check to see if the thermostat has been placed on "Aux." or emergency heat instead of heat mode. If not, your heat pump may have a set point at which the compressor will shut off and not run until the outside temperatures warm above a certain temperature, but still may be a good idea to have the system serviced by a qualified service technician.


    — PEC

  59. 59 Debbie 12 Jan
    My heat pump fan is constantly running cool air(slower air) and then I hear it click on, and hotter air(faster) comes out the vents, then when it reaches the set temp on thermostat, it clicks off the faster warmer air, and goes back to blowing cooler air again! Every once in a while, the fan will click off completely, but it doesn't happen to often! It's a new unit and thermostat, but what's so crazy, is, it was doing that way with the old unit/ thermostat also! I sure hope you can help me figure this out! I have to keep turning it down to a very low degree, so the unit will turn off. A lot of times it will stay @ a degree lower than the set temp, and keep blowing, and other times it's the same temp as the set one, but still continue to blow!!!! Help!!!!!
  60. 60 PEC 13 Jan

    Debbie, Energy Management Representative Chris Denison said it sounds like your auxiliary heat is doing most of the work to keep your home comfortable. When the indoor temperature rises to within 2 degrees of your thermostat setting, the "Aux" heating unit is going off and your system returns to heat pump mode.

    He suggested making sure the outside compressor is running while your system is operating in heat pump mode. If it is not, that is the problem and it's time to call a technician. If the outside unit is running, check the air coming out of the vents in your home to see if it is about 20 degrees warmer than the indoor temperature. If it is not, your heat pump needs to be serviced. If your unit is new it should still be under warranty.

    — PEC

  61. 61 jim 18 Jan

    my old GE heat pump that lasted 30 years, is replaced couple years ago with Trane system that seems to run much more than my old system ran before stopping. also my old system had a blue light to come on when auxiliary system ran., but I have not seen this with the new trane system, should it be there and working? how long off and how long on is good, I have seen my heat pump run near an hour and only be off 10 minutes and come back on again, is it overloaded or sized too small?

  62. 62 PEC 20 Jan

    Jim, Energy Management Representative Chris Denison said there should be an "AUX" indicator in front of or close to the "HEAT" display on the digital thermostat installed with your new system. May not be blue but should be there.

    He said when the outside air temperature is 40 to 50 degrees your heat pump should run about half the time if it is warming properly. He said the auxiliary heat (AUX) should only operate if you increase the setting by more than 2 degrees or if it is below freezing outside.

    To make sure it's working properly, Chris suggested you use a digital cooking thermometer to check the supply air temperature at the vents in your home while your heat pump is operating (not while auxiliary heat is on). The supply air should be more than 20 degrees warmer than the indoor temperature.

    — PEC

  63. 63 Brandon 04 Feb
    Heat pump continues to blow warm air when fan is turned on.  Thermostat is set at 68 but house temp is 82.  Because of this I put the fan on auto, that results in a burning smell that is emitted through the vents.  The burning smell has continued even when I turned the unit off. When examining the indoor unit I noticed it is extremely hot. 
  64. 64 PEC 04 Feb

    Brandon, our Energy Management team recommended you have the unit serviced by a qualified air-conditioning technician. It sounds like one or more of your heating elements is operating continuously, which triggers a limit switch that brings the fan on to remove heat from the furnace air handler. That can result in higher electricity use.

    — PEC

  65. 65 Kevin 28 Feb
    Hi, I went to school for HVAC and worked in the field for a few years and am now a stay at home dad. I have a 2010 Goodman heat pump with gas back up. I also have a free standing wood stove that we use often here in WNC. I programed my thermostat to single cool, single heat with no back up in hopes that I could make the heat pump run without turning on back up heat. There appears to be an outdoor thermostat on the defrost board on the heat pump and the lowest setting as far as I can tell is about 32 degrease so when we get a cold night here below 32 the back up heat attempts to come on anyway. Is there a way for me to bypass that thermostat, and what outdoor temp is the heat pump still efficiant to. I took a course when i was living in Georgia and the instructor was from WNC and said his heat pump still drew heat down to about 17 degrees. Thoughts. 

    Thanks Kevin
  66. 66 Brian 07 Mar


    I am having an issue with my heat pump, when I turn on the heat the outside unit will run but the unit inside will not kick on and no air comes out of the vents. After about 7 minutes or so the aux heat will kick on and air will come out of the vents but the aux heat does not kick on all the time. What do you think my issue might be.? Thanks

  67. 67 PEC 07 Mar

    Kevin, Energy Management Representative Chris Denison said most heat pump systems can still produce heat below freezing temperatures but their individual performance will vary. Manufacturers have individual settings and limit switches that must be manually changed.

    In below freezing temperatures, the system will have to go into defrost cycle at some time when ice forms on the outside condensing unit. Backup heat is essential for the defrost cycle to be effective because the system goes into a/c mode to defrost the outside unit. Without backup heat, you will be cooling the inside of your home when the defrost cycle engages.

    — PEC

  68. 68 PEC 08 Mar

    Chris said it sounds like the auto fan control is malfunctioning, Brian. After the system runs long enough to create heat in the inside unit, the fan is being activated by the heat limit switch in the air handler. You can try turning the fan on manually when the outside unit comes on, but eventually you will need to have the fan switch control checked by an HVAC contractor.

    — PEC

  69. 69 Asha 18 Oct


    I live in VA. We got the heat pump replaced this summer. Last week I turned on the heating since it was 60 degree outside. I set the thermostat to 72 degree. I noticed that for most of the time, my thermostat showed "auxillary heating" indicator. Is it normal to have auxillary heat ON when its 60 degree outside?

  70. 70 Brian Curtsinger 19 Oct

    Asha, the heat pump should not need auxiliary heat at those temperatures. Make sure the thermostat is not on the emergency or auxiliary mode. If it is not in that mode then I would call the A/C contractor who installed it and have it checked out.

    — PEC

  71. 71 Eric 28 Oct
    When Heating.. My Goodman Heat pump will go into Defrost Mode after a few minutes of heat even when it is 55* degrees outside??  Is the defrost board no good?  Any Ideas?
  72. 72 Chris Denison 03 Nov

    Eric, it sounds like there may be a problem with the control board. You should contact an A/C system contractor.

    — PEC

  73. 73 Raymond 14 Nov
    When I set my thermosta to 71 degrees and inside temp is 71 degrees and outside temp is 30 degrees my unit won't shut off and air from the vent is cool what do I need to do
  74. 74 Chris Denison 15 Nov

    Raymond, check to make sure the fan setting on your thermostat is set to "auto." If it's set to "on" the fan will run and circulate air even when your heat pump isn't heating. If that's not the case, your coolant level may be low or the reversing valve could be stuck in the cooling operation mode, either of which would require a service call from your contractor.

    — PEC

  75. 75 Carol D 24 Nov
    My house temperature is 68.  I set my heat pump to 70.  My house temperature heats to 70.  The fan never turns off and blows cool air.  The outside unit doesn't turn.  The auxiliary indicator never comes on.  The thermostat is set to heat and auto. I turn the heat pump off to stop the fan from blowing.  When I turn the heat pump back on with the inside temperature at 70 and the heat pump set for 70 the fan doesn't come back on.  Could my auxiliary indicator not be working? 
  76. 76 Chris Denison 28 Nov

    Carol, if the outside unit doesn't come on it's time to call an HVAC contractor. If the unit is heating without the fan on the outside unit turning, it sounds like your auxiliary heat is operating and the indicator on your thermostat is not. Using only auxiliary heat to warm your home is less efficient and more expensive than using a properly functioning heat pump.

    — PEC

  77. 77 Stephen 11 Dec
    We are going away for the winter - leaving Friday 16th, can I set the temperature for lower than 61F? Thanks
  78. 78 Chris Denison 15 Dec

    Stephen, when it comes to using less electricity, the lower the better; off is best, depending on the threat of freezing pipes. The lowest setting on the thermostat will usually be the best and still prevent anything from freezing in the house.

    — PEC

  79. 79 Mike 16 Dec
    Its currently 24 degrees outside my thermostat is set on 68 but my heat pump runs for about 40 minutes then shuts off for maybe 5 minutes or so then back on auxiliary heat dosent come on but does when i turn it down a couple degrees. Is this normal? 
  80. 80 Don 29 Dec
    My Lennox outside unit in winter runs good for a few days then doesn't run unless you turn breakers off for 30 secs. Then will run for few days more. Board was replaced but same issue???

  81. 81 Amands 30 Dec
    Our heat pump has had a few issues over the last few years, but mainly has been a failure of the AC to cool the home. The HVAC guys come and fix that relatively easy. However, today the heat pump was set at 70° but the unit ran constantly while the temp continued to raise to a steady 79°. We turned the unit off while slightly warm air continued to blow through the vents and it took several hours for the temp to go back down. It did feel great as its around 10° outside... but it is not good for the power bill! 
  82. 82 Chris Denison 30 Dec

    Don, something is having to reset during that break, most likely some component of the control board. You'll need to consult a technician, who can determine whether the furnace breaker or the air conditioner compressor breaker is needing to reset.

    — PEC

  83. 83 Chris Denison 30 Dec

    Amands, either the thermostat or the control board is not communicating properly with the unit. You'll need to consult a technician, but if you've used the same company repeatedly and still have issues, you might consider trying a different contractor.

    — PEC

  84. 84 Pam 06 Jan
    My heat pump unit outside seems to run continually when it is very cold. We have had a wind chill of 12 and it seems to stay on. Is this a problem?
  85. 85 Kyle 07 Jan
    I have a heat pump that constantly runs, copper line running inside to blower is warm, and thermostat shows aux heat is on. It is about 15 degrees f outside, I have thermostat set on 72. Never gets past 69. I have had two techs look at it, and they say everything is normal. It will blow warm air every so often and then back to cold. Why can it not reach temp and take a break for awhile?
  86. 86 Nicole 08 Jan
    Hello, I just had my condenser fan motor replaced 2 weeks ago. The outdoor unit has stopped working again. Turned emergency heat on for a few hours and it didn't do much.
    TStat is set on 70, its was 57 at 6am when we realize the outdoor unit was off . The emergency heat made it come up to 59 in 4 hours. I turned the regular heat back on just to see what it would do and it started working. Its set on 70 and the air coming out is 75
  87. 87 Ariann 08 Jan
    We were getting ready for a very cold night of 20 degree temps. Set thermostat to 68 (our  normal sleep temp) and went to bed. Noticed before we went into the bedroom that the thermostat was now reading 65. The heat pump ran all night on aux heat and when we woke the next morning and the living room was very cold. Checked the thermostat and the inside temp had dropped to 55 and the aux heat was still running! This is a brand new heat pump.
  88. 88 Mitzi 08 Jan
    My unit is running outside and has been heating the house. Today the aid has been on and it kicks in but nothing comes out of the vents. What should I do?
  89. 89 Joy 09 Jan
    I've been questioning my heat pump and furnace for years. When the temperature drops below 40 degrees the heat pump goes into auxiliary mode which I understand is normal but the furnace/air handler does not bring the temperature to the set temperature i.e. Set to 68 degrees but only gets to maybe 66 degrees. Lower the temp outside the larger the gap.   The heat pump itself has been fixed a couple of times (they are both about 10 years old)  but once we hit below 40 degrees it   We only get the cold temps a few times a year.    Now I'm thinking air handler rather than heat pump itself. 
  90. 90 Wiliam 09 Jan
    My wife and I just moved into our home. Our heat pump is considerably older, Date of Man. is 12/91. Since we have lived here, about a month, we have had the heat set to ON and the fan set to AUTO. We received our first electric bill and it was not what it should have been, extremely high for a smaller house. This is when I noticed the outdoor fan does not turn off very much and, more times than not, the AUX Heat setting turns on. We keep the thermostat set between 70 and 71 degrees and the house is always at the set temperature. When working on the house to move in, it DID seem to work properly. Could this be something simple, or something major? The air that comes from the vents is normally cooler, until the AUX Heat kicks in and it is substantially warmer. 
  91. 91 Brenda 14 Jan
    My AUX, came on this pass weekend. The temp. outside was 19degree. It stayed on for two days. Warm air was coming out. Now that the temp. is back in the 70 degree. What should i do. 
  92. 92 Robin 04 Feb
    My AUX is coming on on my system just going from 65 to 66 or just keeping the heat at 60 at night.  This is the second winter we have had this lennox, and I don't  ever remember the AUX coming on before.  What is going on?
  93. 93 Jimmy 13 Mar
    I have a trane heat pump. When it gets 45 to 50degrees outside the unit outside turns on and off within a few secs for several times meaning 6 or 7 before staying on. Temp in house set to 70 and once it gets 69 degrees this is when this happens. Or within 1 degree of set temp. My AC guy says I need to run the unit in emergency heat when it gets 35 or so degrees. I thought the unit was suppose to have a 2-3 degree variance before unit turns on. The unit is now 3 years old and only reason I noticed it because I moved to that side of the house of unit. The Carrier was my previous unit so we still have that as the air handler if that should matter. Could there be wires crossed when unit was installed. I know this is not good for the unit continious on and off.  Thanks Jimmy
  94. 94 Chris Denison 14 Mar

    Jimmy, it sounds like there may be an issue with the sensitivity of the variance in the thermostat, and, yes, once the outside temperature gets close to freezing, you might as well go to “Emergency Heat” to reduce wear and tear on the heat pump.

    — PEC

  95. 95 Teresa 09 Apr
    Could you answer something for me, how does heat pump temperatures compare to outside temps?? My husband thinks 70 on the thermostat feels the same as 70 outside I disagree. In winter the house could say 70 but I still feel cold. It's an argument that is ongoing. Hope this makes sense.
  96. 96 Chris Denison 10 Apr

    Teresa, to confirm the temperature, calibrate your thermostat with another digital thermometer to insure it is accurate, then take the thermometer outside to verify ambient temperature.

    Although 70 degrees is 70 degrees, remember that humidity and wind chill can affect skin surface sensitivity, so you may 'feel' more comfortable inside where humidity is controlled by your HVAC unit.

    — PEC

  97. 97 Tom 20 Nov
    ws8I have a 18 month old Trane Heat Pump that heat shuts off with fan still running before reaching thermostat setting. After room temp drops a few degrees it will start heating again. Only does this when heat is on and not everytime. Trane service tech replaced thermostat last winter and now its doing it again.
  98. 98 donna 22 Nov
    could you help me please. why when it is 37 degrees outside my auxillary will come on, but when it is 31 it doesn't.  also when the aux will not come on, the heat pump will run for 30 minutes or better. but when the aux is n it only runs for about 6 minutes. thank you 


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