If you are having problems with your heat pump shutting off prematurely, there are several potential causes.

Most heat pumps have a built-in safety feature/sensor that causes the unit to shut down if it gets too hot.

This is to prevent damage to the heat pump and keep it from becoming a fire hazard.

However, if your heat pump is shutting off even when it’s not especially hot outside, this could be a sign of a problem. Oftentimes it is a problem of short-cycling, which is when the heat pump turns on and off more frequently than normal.

It’s important to have any potential causes of short cycling diagnosed and repaired as soon as possible to avoid further damage to your heat pump.

Let’s take a look at some of the potential causes of a heat pump shutting off prematurely and some troubleshooting options.

Thermostat Inaccuracy

One of the main reasons why your heat pump may be shutting off prematurely is because the thermostat is inaccurate.

If the thermostat is not reading the temperature correctly, it will cause the heat pump to turn off prematurely.

Related: Heat Pump Advantages and Disadvantages

Use a digital thermometer

There are a few ways to test whether or not your thermostat is accurate. One way is to use a digital thermometer to measure the temperature in the room where the thermostat is located.

Compare this number to what the thermostat is reading. If there is a big difference, then you know the thermostat is inaccurate and needs to be replaced.

May need re-calibrating

Another way to test your thermostat’s accuracy is to turn on the heat pump and set the temperature 10 degrees higher than the current temperature.

After 30 minutes, see if the room has reached the desired temperature.

If it has not, then the thermostat is inaccurate and needs to be recalibrated or replaced.

Thermostat temperature sensor wrong

Sometimes, the problem is not with the thermostat itself, but with the temperature sensor. This is the part of the thermostat that actually measures the temperature in the room.

If this sensor is not working correctly, it will cause the thermostat to read the wrong temperature and turn off prematurely.

It may also cause the heat pump to run for too long and use more energy than necessary.

To fix this problem, you will need to replace the temperature sensor.

Related: The Top Problems With Ground Source Heat Pumps

Clogged Air Filter

One potential cause is a dirty air filter. If the air filter is clogged, it can restrict airflow and cause the heat pump to overheat.

Unless cleaning and clearing the air filter is a scheduled maintenance item for your heat pump, it’s a good idea to check and clean it every few months.

Dirty coils

Another potential cause of your heat pump shutting off prematurely is dirty coils.

The coils are responsible for transferring heat from the air to the refrigerant. If they are dirty, they will not be able to transfer heat as effectively and the heat pump will overheat.

To clean the coils, you will need to remove them from the unit and wash them with a mild soap and water solution.

You can also use a coil cleaning brush to help remove any debris that may be stuck on the coils. Once they are clean, you can put them back in the unit and turn them on.

How often should you change the air filter?

All heat pumps are different and the time to replace the air filter will be different from model to model. As a rule of thumb, every 90 days is a good time frame to change the air filter.

If you have pets or live in an area with a lot of dust, you may need to replace it more often.

Can a dirty air filter or duct make you sick?

If you suffer from allergies or have asthma, a dirty air filter or duct can make your symptoms worse. Dust, pollen, and other allergens can get trapped in the filter or duct and be recirculated into the air you breathe.

If you have a chronic respiratory condition, it’s important to keep the air filter and duct clean to prevent exacerbating your symptoms.

Effects of not changing the air filter in your house

  • Your air filter will become clogged with dust and other particles.
  • It will take longer to make your home your desired temperature.
  • Your energy bills will rise.
  • Your indoor air quality will decrease.
  • Your heat pump’s system components will not last as long.

Leaking Refrigerant (Or Low)

If your heat pump is low on refrigerant or has a leak, it will cause the unit to work harder than it should. This can lead to the unit overheating and shutting off prematurely.

To fix this problem, you will need to add refrigerant to the unit or repair any leaks that may be present. You should never attempt to do this yourself as it can be dangerous. Always call a professional to help you with this problem.

Frozen Evaporator coils

Another potential cause of your heat pump shutting off prematurely is frozen evaporator coils. The evaporator coils are responsible for transferring heat from the air to the refrigerant.

If they are frozen, they will not be able to transfer heat as effectively and the heat pump will overheat.

To thaw the coils, you will need to turn off the unit and let it thaw on its own. Once it is thawed, you can turn the unit back on.

It’s also a good idea to check the coils regularly to ensure they are not frozen.

If you find that they are frozen more often than not, there may be a problem with the Freon levels in your unit.

You will need to have a professional come out and take a look at your unit to determine what is causing the problem.

Related: Here’s What to do if your Heat Pump is Frozen

Wrong Sized Heat Pump 

If you have a wrong-sized heat pump, this means that it was not fitted by a qualified professional. This can cause a number of problems, one of which is the heat pump shutting off prematurely.

A wrong-sized heat pump will not be able to cool or heat your home as effectively as a properly sized unit. This can lead to the unit working harder than it should and eventually shutting off.

If you have a wrong-sized heat pump, you will need to have it replaced with a properly sized unit. Always make sure that you hire a qualified professional to do this job for you.

They will check things like the heat load calculation (also called a manual J calculation). This will determine the optimum heat pump power output that is right for your home.

In Summary

So there you have it, some of the potential causes of your heat pump shutting off prematurely. If you are having this problem, it’s important to have it looked at by a professional.

They will be able to diagnose the problem and recommend the best course of action to take. In most cases, the problem can be easily fixed and your heat pump will be back to working as it should in no time.

About the Author

Passionate about helping households transition to sustainable energy with helpful information and resources.

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