Unit with the top off - condenser fan motor being changed out and inspected

Heat Pump being repaired

Heat Pump Troubleshooting Advice. When you have a problem with your heat pump, you want to check the basics. Anything beyond that, you need to call in a professional to troubleshoot the heat pump. The heat pump or any electrical-mechanical equipment you have problems with and need to troubleshoot. Whether you call for heat pump troubleshooting or any other repair there is only so much you can do. We’ll discuss common problems and give you the best advice.


Heat Pump Troubleshooting | No Heat or Cool Checklist

A heat pump with no heat or not cooling (in the summertime) is a problem. Here are some simple heat pump troubleshooting steps you can take to fix the heat pump problem, hopefully. For this heat pump troubleshooting guide, we cover the indoor unit and the outdoor unit for common problems. Before calling a heating and air conditioning company, check the following:

  1. Thermostat
  2. Power Supply
  3. Ice or Freezing - both the indoor unit and the outdoor unit
  4. Air Flow - the indoor unit - Check the air filter first
  5. Condenser Fan Motor - the outdoor unit
  6. Refrigeration Problem - likely to require heat pump troubleshooting from an expert

A basic description of the heat pump troubleshooting guide of the above list is found below. This is designed to give you the basics of heat pump troubleshooting and guide you through common problems with both the air handler and the outdoor unit.

1. Heat Pump Thermostat

Check selections on the thermostat. Ensure that the setpoint setting is at the desired settings. I’ve responded to service calls where the homeowner made a no heat or no cool call. I found they had the thermostat set to heat when they wanted to cool. Or set to cooling when they wanted heat. Additionally, make sure the set point is correct. For example, if you want the heat pump to heat, make sure the thermostat is set to heat.

Furthermore, if the temperature in the house is 65° F, make sure you turn the thermostat setting up above 65° F. to get heat. Finally, for heat pump troubleshooting, this is always the first place to start. At the thermostat.

2. Power Supply

Check power supply. That can include a heat pump circuit breaker and or/a regular-looking wall switch close to the unit. That is another easy fix. I have responded to heat pump no heat or heat pump, not cooling calls, only to find the power was off inadvertently. Perhaps relatives were visiting, and someone mistook the wall switch for a light switch. These switches are typically not on heat pumps as a heat pump liking has a breaker next to the heat pump.

Make sure you check the breaker at the air handler and the breaker in the main panel. A typical split system will have separate breakers. One for the condenser and one for the air handler. Step 2 in heat pump troubleshooting is to check the power supply.

3. Ice or Freezing | Hate Pump Troubleshooting No Heat

In the summer check for freezing up of the heat pump. If the air heat pump unit is frozen, turn it off. Check the air filter(s) to make sure they are not clogged or obstructed in any way. Air filters are essential to the operation and need to be clean. In the summer, if the evaporator coil has ice on it or any of the copper pipes have ice on them, then you have a problem that needs the attention of a professional. If you find no problems leave the unit turned off, and call a service company.

In the winter, check the condenser (outdoor unit) does not have excessive ice on the coils. That could mean the defrost mode isn’t working properly and may need a minor adjustment or a repair altogether. It is best to call a pro to fix that issue. Step 3 for heat pump troubleshooting is to check for ice or freezing.

4. Airflow

The air handler is typically located inside. You should know where the air filter is located. Sometimes the air filter is located in a filter rack and other times the air filter is located in the air handler. Make sure the air filter is clean. Check for multiple air filters. Clean filters are essential to good indoor airflow.

Is the air handler blower working well and blowing air out of all of the supply vents? If not or it is weak, then you likely have an airflow issue. Always make sure you have a clean air filter and that all of your supply vents are open and unobstructed. If this is all good, then you have another problem with the airflow.

Maybe a bad heat pump blower motor, the unit is freezing up inside the evaporator coil, or collapsed ductwork. In any of these cases, it is time to call an HVAC repair service. Bad airflow indicates a serious problem. The step for heat pump troubleshooting is to check the airflow. If the heat pump blower runs all the time check here.

5. Condenser Fan Motor

Is the condenser fan motor turning at the heat pump condenser? Word of note - sometimes in the winter or when you have the heat pump in heating mode, the fan will not turn while the compressor is running. That is normal, and a part of the automatic defrost mode for the heat pump. The condenser fan motor is located in the outdoor unit.

If the fan is not turning, but you hear the compressor running, then something is wrong (unless as noted above with defrost mode), and you need to call a professional. Step 5 in heat pump troubleshooting is to check the condenser fan motor. If you have a bad condenser fan motor see here.

Heat Pump Diagram
Heat Pump Diagram

The above illustration shows the refrigeration components of a heat pump system. Understanding the components and how they work together helps one have the ability to troubleshooting a heat pump.

Heat Pump Diagnosis & Repair Guide

Additional Helpful Heat PumpTroubleshooting Hints

  • Always change your air filter on a monthly basis. If not clean, the system may not function properly.
  • Make sure all your supply vents are open and unobstructed
  • Keep the area clean around the indoor unit especially the return grills
  • Keep outdoor condensing units free of leaves, grass, and debris including trash cans and/or children’s toys or playthings like small plastic pools or playhouses. Additionally, your service technician will appreciate you not planting holly bushes near the outside unit
  • Have air conditioner, heat pump, or furnace system serviced every six months

Heat Pump Troubleshooting Flow Guide

Heat Pump Troubleshooting Flow Matrix
Problem Process or ComponentWhat to Check/Do for Troubleshooting
Thermostat1) Check the settings of the thermostat. Make sure it is in heating mode and the set point at the desired position.
2) If you have an older mercury switch type of thermostat make sure it is level.
3) If you have a digital thermostat and the display is blank then you have either a bad thermostat or a power problem. Likely this is a power problem. Check all the power switches for the system including the circuit breakers. Call for service if that doesn't resolve the problem.
Power Supply1) A heat pump can have several different breakers. In the main circuit breaker panel you should have one for the air handler and one for the condenser. Both of these need to be on. If you reset the breaker and the heat pump breaker trips again then you have a serious problem and need to call for service.
2) Additional to the main panel breakers you could also have breakers or fuses at the air handler and the condensing unit. Check these after checking the main panel breaker box. Again, if you reset a breaker and it trips again you should call for service. Same thing if the system utilizes fuses instead of breakers. If the replacement fuse blows after replacing the blown fuse you need to call for service.
3) Control Power - this is the control power that comes from a control transformer. The control transformer gets it voltage from the main power supply. If everything is okay with the main power supply (no blown fuses or tripped breakers) and the display on the thermostat is blank(as mentioned above) then it is possible you have a control power problem. This can occur with a blown control fuse or blown transformer. Often this is a direct result of a dead short in the wiring Call for service.
Ice or Freezing1) Ice or freezing of the condensing unit can be because of a problem with the defrost cycle. The quickest way to solve this problem and get heat is to turn the thermostat to air conditioning mode. When the ice is gone turn the thermostat back to heating mode. Then call for service.
2) Ensure there are no obstructions around the heat pump condensing unit located outside. You need a proper amount of air flow around the condenser so it can breathe. The heat pump pulls air from the outside air even when it is cold outside. It then delivers this heat inside to keep you warm.
Air Flow1) Always ensure you have the proper amount of air flow inside. This means making sure you have clean filters. Clogged and dirty filters can cause severe issues with air flow and that can cause it to malfunction. A regular filter maintenace schedule should be made and adhered to year round. Check the filter and change as necessary.
2) Low air flow with clean filters could mean you have a problem with the blower motor. The blower is about to go bad, is bad, or another component that controls the blower has malfunctioned. Call for service.
3) The duct work has collapsed or is restricted. Make sure all your supply vents are open. Visually check the duct work to make sure nothing has caused it to collapse or be restricted.
Refrigeration Problem (Advanced Problems that will require a service call)1) A low refrigerant charge can cause problems with a heat pump and providing good efficient heat. If you have noticed the heat pump has been struggling and the temperatures outside are not terribly bad you may want to call for service to have it checked.
2) Compressor is not working. This can be because of a bad component for the compressor such as a capacitor or contactor. It could also mean a bad compressor. Call for service.
3) Defrost Problem. The defrost board could be bad or something else causing it not to function properly. Call for service.
4) Reversing valve problem. The reversing valve switches the heat pump condenser from heating to cooling. Call for service.
5) Bad condenser fan motor. Call for service. Note that some heat pumps, when in the defrost mode, the condenser fan motor will not run.
Heat Pump Troubleshooting Flow Guide

Heat Pump Troubleshooting Repair

Heat Pump Repair Advice Advisory

When you read the information on the web double check that the information is correct.

I read this directly from an un-named article on the internet that has a number one position in a search for troubleshooting heat pumps – “check the heat pumps ignition”. What? Can you say that one more time? It is obvious to me the person who wrote that article has never touched a heat pump in their life and should have never written an article for troubleshooting heat pumps. Can someone please tell me where the igniter is on a heat pump?

I’ve was out of the field for a year doing management work and now I am doing engineering work and occasionally going out to the field but I do not think the basic concept of heat pumps has changed that much to include adding ignition systems to heat pumps. If you are going to troubleshoot your own heat pump then please follow the basics above. Beyond that please call a professional to repair your heat pump or troubleshoot your air conditioner.
adjusting and checking the heat pump thermostat is necessary

Turning Faulty Advice into Good Advice

Some other faulty advice from around the web:

Heat Pump Troubleshooting Advice – “Most of the time when your heat pump doesn’t work it is a faulty thermostat”. I’ve been on many service calls and I have found faulty thermostats. Most of the time the reason for a faulty thermostat is because the homeowner thought the thermostat was bad and then decided to change it. Changing parts, especially the thermostat, simply doesn’t work most of the time.

Whatever reason the homeowner didn’t wire it properly, or they didn’t turn the power off and crossed the wrong wires and burned up the heating anticipator or blew the transformer. Unless you have had a lightning strike, a major power surge that took out other electronic devices in your home, or someone took a hammer to the thermostat, and then your problem is probably not the thermostat.

Furthermore, if you have problems with your heat pump or air conditioner and want to troubleshoot the problem yourself, check the settings of the thermostat. Make sure the setting is the appropriate setting. Double-check to make sure it is set to the appropriate setting. Believe me, I have been on more than one service where the setting on the thermostat was incorrect.

Parts Changers Rarely Make the Repair | Heat Pump Troubleshooting Guide

If everything is correct, then you are done with the thermostat. Don’t run down to your local hardware store and buy a new thermostat for your heat pump, thinking it will solve the problem. Chances are, if you were doing it as a part of the process of finding the problem with your heat pump, then you will probably still be cold after changing the thermostat in the process of troubleshooting a heat pump.

Moreover, you can change every single part of the heat pump system and still have a problem with the heat pump. Furthermore, changing parts, especially the thermostat, doesn’t work most of the time.

Blower Motors

Heat Pump Troubleshooting Advice - no oil plugs on this motor which is variable speedHeat Pump Troubleshooting Advice - “The motor may need to be reset” is another thing that struck me from reading this article for troubleshooting heat pumps – Reset the motor? I have not seen many blower motors that have a reset button on them. There are very few out there that have reset buttons on the blower motor, but chances are you do not have the type of motor that has a reset button on it.

Furthermore, it seems to be the person who wrote this article read an article on oil furnaces or boilers and tried to adapt it to troubleshooting heat pumps. Oil burners have reset buttons on them but not on the blower – the reset button is on the burner as a part of the burner ignition controls.

If there are any manual reset buttons on the heat pump, there may be a manual reset button on the condensing unit. Furthermore, I know of only two manufacturers that have these reset buttons on their heat pumps. Rheem and Ruud. These reset buttons are on the outdoor unit and usually have a red button. They are designed to trip the outdoor unit off because of a head pressure problem. Not all Rheem or Ruud heat pumps have these reset switches.

To Reset or Not to Reset

This is not a reset button for any motor, but a high-pressure reset switch. If this switch needs resetting on a heat pump, it means the head pressure or the high-pressure side of the heat pump is exceeding maximum pressure. Furthermore, it is killing power to the outdoor unit as it should avoid damaging the compressor or other components in the refrigeration loop of the heat pump. That means one of several reasons if you are repairing the heat pump.

Furthermore, the condenser coils are plugged up with trash, dirt, or other debris like grass, the condenser fan motor has failed, or there is a refrigeration problem such as an overcharge of refrigerant in the system.

Circuit Breakers

Heat Pump Troubleshooting Advice - “Heat Pump trips the circuit breaker” – they tell you to check the heat pump circuit breaker in this bad article. Which heat pump breaker do I check? Moreover, a real heat pump has two circuit breakers in the circuit breaker panel for the home and if the heat pump has electric backup heat then it should have another set of breakers or fuse protection at the location where the heat strips are which is usually in the air handler.

Yes, a real heat pump (not the fictional dream heat pump they describe in this heat pump repair article) has two circuit breakers. One for the heat pump condenser and one for the air handler. If the breakers are tripping on the heat pump circuit, then you have a dead short somewhere in the system, and it needs to be addressed by a professional. This problem needs a profession for heat pump troubleshooting because of high voltage which can be dangerous.

Air Handlers

“Air Handler Squeals” – they tell you that it is usually the belt. Huh? In the residential market, HVAC manufacturers went to direct drive blowers many, many moons ago and stopped distributing units that are belt driven. 99.9% of heat pump air handlers out there installed in homes are direct drive. Finding a belt-driven blower in residential systems is akin to finding a Model T. If your heat pump is this old it is time to replace the system and not the belt.

Sequence of Operation | Heat Pump Troubleshooting Guide

Every manufacturer follows a basic heat pump sequence of operation but within those sequences of operations, there are some distinctions. For example, Rheem and Ruud will energize the reversing valve for a heat setting rather than a cool setting on the thermostat. Why would this make a difference? Because if a particular component fails (such as the reversing valve in this case) you want it to fail to the heating mode. Heat is far more important than cooling.

If the heat fails in the wintertime it can lead to serious issues that can be life-threatening and property threatening. Pipes can freeze and other hazardous conditions from cold weather can occur. While if the components fail to “cooling” or AC mode we would be cool but in this regard, heating is considered far more important than cooling. All other brands, as far as we know at the time of publishing this article, fail to heat except for Rheem and Ruud.


In modern times, most brands use a printed circuit board to control the automatic sequence of operations with thermostats providing manual operations by the user. If you want heat you set the thermostat to heat and the thermostat and control board takes care of the rest. Same with cooling. If something goes wrong with the heat pump a printed circuit can detect the problem and shut the system down.

In some cases, this is done for safety while in other cases this is done to protect the heat pump from further damage. If a problem develops and your heat pump is not working properly, call in a service company to diagnose and repair the problem.

Conclusion | Heat Pump Diagnosis Repair

If troubleshooting heat pumps is your profession, please go ahead and fix it. Chances are you are not a professional HVAC technician, so please check the basics. Furthermore, leave it up to the professional HVAC Technician to troubleshoot the heat pump.

High Performance HVAC

High Performance HVAC Heat Pump Troubleshooting and Repair Advice

Heat Pump Troubleshooting Video