Heat Pump not Turning On
Troubleshooting and Repair Tips

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There are many problems a homeowner could encounter with their heat pump. Some (simple) ones could be fixed on your own, while others need professional help. Heat pumps not turning on is a common complaint. By extension, this also means that their heat pump does not heat or cool.

This article will discuss the causes of this problem and how to troubleshoot it.

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Troubleshooting a non-running heat pump

Heat pumps may not turn on for many reasons, and electricity is one of those. Power outage in your area is one, but that’s beyond our control. Electric-related causes may include components in your house related to your heat pump like wiring and circuits.

We will discuss some of those here, along with other problems and causes. Try troubleshooting some of these problems with the given tips by yourself first. Some issues might not even require professional help. What can you check for if your heat pump is not turning on?

Thermostat-related problems

Always check the thermostat first before checking the outdoor unit. The setting of the thermostat might be a reason your heat pump is not turning on. Set the thermostat to “cool” or “hot” based on your desired temperature.

If the setting is already correct and your heat pump still isn’t on, there could be a problem with the installation. Some of the possible problems and solutions may include:

  • The thermostat you installed is not compatible with the heat pump. Not all thermostats are designed for heat pumps. 
  • Your thermostat is not wired correctly. The circuits of your heat pump’s components might get fried in this situation and cause the unit to malfunction.
  • Your thermostat is not sending signals properly to your heat pump. You may need to get an HVAC technician to check on this.
  • Your thermostat is set in emergency heat mode. This will shut down most of your heat pump’s operations. Reset your thermostat.

In other words, your thermostat is not calibrated properly. This is aside from your thermostat not being in the proper setting. For that problem, there is a quick test you can do to troubleshoot.

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Quick thermostat test

You can run this quick thermostat test if your fan is running. This test needs you to set your thermostat 5 degrees above or below the room temperature. After a minute, check your vents for flowing warm/cold air. Your thermostat is most likely okay if there is warm/cold air flowing. Otherwise, you might need to check both your thermostat and air handler. Keep in mind that warm/cold air is not always a reassurance. You might want to check a device for any malfunctions as well.

Power-related causes

Problems in electrical systems are also plausible causes apart from the occasional power outages in your area. Power-related causes usually involve your fuses or circuit breakers. Here are some things you can do to troubleshoot these problems.

Power switches

Check your unit’s power switch first before going for the circuit breakers, though do note that not all heat pumps have switches. But if your heat pump has one, it should be in the cabinet near the air handler.

Switch it on if it isn’t yet. Wait for the fan to start running afterward. However, if it still doesn’t run, check your circuit breakers. You might also need to check your emergency switches. Switch them off if they are not.

Tripped circuit breakers

Tripped circuit breakers are common causes of non-running heat pumps along with blown fuses. Circuit breakers sometimes trip because of the heat pumps. For troubleshooting, you can check the main electric boards and subpanels connected to the heat pump. These are the parts that usually supply power to your heat pump. 

Usually, flipping the switches on and off again can fix tripped breakers.     Replace the fuse if it’s blown. However, you might need professional help if your heat pump keeps tripping your circuit breakers and if there are faulty or burnt wires in the thermostat.

Component and unit-related problems

You might also need to check the other parts of your heat pump. This usually includes the inner parts like the compressor, valves, the start capacitor, condensate pump, etc. Your outdoor unit might also be in a condition where it won’t turn on.

If one part fails, the rest of the heat pump will follow. So, it’s essential to check on them from time to time. These might highly require skilled technicians to troubleshoot. There’s a big chance that these parts might need replacement.

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Reversing valve

The valve’s job is to make sure that the refrigerant is flowing in the proper direction. If the heat pump cools but not heats and vice versa, there might be a problem. Your heat pump’s mode determines the flow of the refrigerant, and replacement is needed if it only performs in one of these.

Start capacitor

The capacitor’s job is to kickstart your heat pump by sending electrical signals to the motors. Watch closely on this component, too, and check your cabinet for clicking noises when you turn on your heat pump. That’s a common sign that your capacitor is failing. Call your local maintenance to check its condition.

Time delay relay

A time delay relay acts as a timer to keep electricity from continually running in the coils. It prevents your unit from short-cycling (turning on and off repeatedly), thus, keeping your heat pump from wearing out quickly. So, if your heat pump starts short-cycling more often, the time delay relay might be malfunctioning.

Other related causes

We’ve tackled the general problems and causes for a heat pump not turning on. Other reasons for a heat pump not turning on may include weather and various malfunctions in other components. By extension, your heat pump not cooling or heating your home, might also be related to this problem. Here’s a quick rundown of some other causes of the problem.

Frozen heat pump

It’s normal for the snow to accumulate on a heat pump during winter. But if your heat pump doesn’t run, it’s coils and fan might be frozen. This may cause other components like your compressor to malfunction. Hose them down with water. Do not pick on it with a sharp object as it may damage the heat pump’s parts. If it’s the indoor coil that’s frozen, run the heat pump in fan mode to defrost it.


Make sure to check for leaks in the ducts and the refrigerant. Leaks will cause low refrigerant levels, thus keeping your heat pump from heating or cooling. Get this fixed by your local technician.

Other maintenance tips

Regular maintenance and tune-ups are a given. Check all the parts of the heat pump, from the circuits to the thermostat, to the unit itself. Look and listen for any signs of abnormal activity like humming noises and sudden shutdowns. For anything else, you might want to get checked, make sure to get professional help.

These are the possible reasons your heat pump is not turning on. Remember always to check all the heat pumps components before calling maintenance because some of these problems could be fixed alone.


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