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Why Is My Heat Pump Freezing In The Summer?

Aug 01, 2022



When the heat officially hits, the last thing you want is a heat pump freezing up in summer. Dealing with cooling issues in your home during the hottest months of the year is a recipe for discomfort and aggravation. If you find your furnace leaking water in summer or are wondering, “why is my heat pump freezing up in summer?” then you’ve come to the right place.


This guide will help you understand how your heat pump works and why you might be dealing with your HVAC freezing up in summer. Read on to learn more about your home’s HVAC system, how you can keep it operating properly, and what to do if you find your heat pump freezing up in summer

What is a Heat Pump?

There are two common types of heat pumps: air-source and ground-source. Similar to an air conditioner, heat pumps work to cool your home -- but they can also provide heat in the winter. Rather than creating heat, they pull it from the air or ground (depending on the heat pump type). Heat pumps are powered by electricity and transfer heat to or from the home all year round. 


An air-source heat pump transfers heat between the indoor and outdoor air. In the summer, it transfers hot air inside the home out, and in the winter, it transfers warm air from outside into the home. 


Ground-source heat pumps are a little different. Often called geothermal heat pumps, they transfer heat to-and-from the ground. They are more expensive and require a complicated installation process, but have a lower operating cost.

How Does a Heat Pump Work?

Heat pumps work by redistributing heat or cooling rather than creating it. They circulate air using an indoor fan coil unit (the air handler) as well as an outdoor compressor that transfers heat. 


When in cooling mode, heat pumps absorb the indoor heat from your home and release it outdoors, then perform the opposite when heating your home: they absorb heat from the outdoor air -- even from cold air -- and send it inside your home.


Heat pumps are most common in areas with milder climates. Heat pumps work best in areas where the temperature rarely drops below freezing. In colder climates, they are often paired with a furnace to help on cold days. 

The Main Elements of a Heat Pump

Understanding the main elements of your heat pump can help you understand how it works, which in turn helps you maintain your unit and keep it running optimally for longer. Here are the main components of a heat pump:


  • Exterior unit (including a coil for cooling and an evaporator for heating)
  • Indoor unit (includes a coil and fan for moving air through your home)
  • Refrigerant (for absorbing and releasing heat)
  • Compressor (for pressurizing the refrigerant)
  • Reversing valve (to help shift the unit from heating to cooling)
  • Expansion valve (to regulate the refrigerant)

How to Identify a Heat Pump Freezing Up in Summer

Monitoring your heat pump is fairly straightforward. Over the hot months when it’s common for HVAC freezing up in summer, keep an eye out for any frost on the indoor unit’s evaporator coil. If you have a furnace, look for your furnace leaking water in the summer. Pay attention to your cooling to ensure the temperature in your home stays comfortable and set at your desired degree.


If anything ever seems off or if you notice ice on your heat pump’s evaporator coils -- even a thin, small layer -- then you should shut off your unit and stop using it. Turn the fan from “auto” to “on” to help defrost any ice and call an HVAC professional to help resolve the issue before it triggers a system breakdown.

Why Is My Heat Pump Freezing Up in Summer?

It’s normal to be confused about how an HVAC system can freeze over during the hot months of the year. It’s hot outside, so it seems backwards that you’re seeing ice build-up. If you think about it, however, then it does make sense. Your heat pumps work to cool your home by cooling temperatures over refrigerant running through the evaporator coils. As warm air hits the coils, condensation can build up. If the coil gets too cold and if there’s too much condensation, it can freeze, triggering your unit into freezing over during the summer.

Reasons Why a Heat Pump Freezing Up in Summer

Low Refrigerant

If your unit is running low on refrigerant, this can trigger a pressure drop. This causes the coils to get much colder than normal. This is the most common cause of frozen coils.

Dirty Coils

If there is a lot of dirt building up on your evaporator coils, that makes them almost insulated against warm air blowing. This layer of dirt causes your coils to get cooler and cooler, causing them to freeze over. Changing your air filters regularly and getting your unit professionally cleaned can help prevent this issue.

Poor Airflow

If there are blocked return vents, dirty filters, or a bad blower, this can all lead to bad airflow. A lack of warm air blowing on your evaporator coils can cause them to freeze over. Again, keeping your filters and HVAC unit clean can help prevent this problem.

Reach out for Professional Heat Pump Maintenance

If you notice your heat pump isn’t working how it should, check for any signs of freezing on the evaporator coils. If your heat pump freezes up in summer, shut it off and reach out for help. CroppMetcalfe is ready to service your unit with high-quality heat pump repair. Our HVAC technicians are some of the best in the industry and are ready to handle your home project. Reach out today or schedule your service appointment online.



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