Why Is My Heat Pump Freezing Up In the Summer: Causes and Fixes

The last thing you might expect on a hot, muggy day is to discover ice in your heat pump system. While it might not make sense initially, it’s actually a common problem with heat pumps and central air conditioning systems. 

A heat pump that’s freezing up in the summer can cause a host of issues including damage to your home and system. HVAC.com explains common causes of a frozen heat pump in the summer and discusses solutions to unthaw your system so it works properly again.

Identifying a Frozen Heat Pump

Although it’s quite common for a heat pump’s outdoor coil to freeze up in harsh winter conditions, especially if the defrost cycle malfunctions, it’s the inside evaporator coil that is most likely to freeze up during the summer months.

Homeowners can identify a frozen heat pump in the summer by observing signs such as reduced airflow, a lack of cool air, the system continuously running without achieving the desired temperature, or water leaks around the indoor unit.

Common Reasons a Heat Pump Freezes Up In the Summer

Let’s delve into some of the reasons your heat pump may ice up:

Restricted Airflow

Restricted airflow often leads to a frozen heat pump evaporator coil, with dirty air filters, blocked vents or registers, leaky air ducts, and faulty blower motors usually the culprits. Restricted airflow can cause the evaporator coil to become too cold, causing condensation to freeze on its surface. In severe cases, the entire evaporator coil can become a solid block of ice.

Low Refrigerant Levels

Low refrigerant levels can result from leaks in the system, which cause a decrease in pressure and temperature. When refrigerant levels are low, the evaporator coil can’t absorb enough heat from the surrounding air, leading to freezing.

Thermostat Issues

Even a malfunctioning thermostat can lead to longer cycles than necessary, causing the evaporator coil to overcool. If the thermostat isn’t working properly, it can lead to longer cycles and eventually a frozen coil.

How to Fix a Heat Pump that’s Freezing Up

When faced with a frozen heat pump, address the issue promptly to prevent further damage. Here are some solutions:

1. Turn Off the System: The first step is to turn off your heat pump to prevent further icing and potential damage. Allow the system to completely thaw before attempting any repairs.
2. Improve Airflow: Check and replace dirty air filters regularly to ensure proper airflow. Also, remove any objects such as carpeting or furniture from vents and registers. Sufficient airflow is crucial for preventing the evaporator coil from freezing.
3. Check Refrigerant Levels: Contact a professional HVAC technician if you suspect a refrigerant leak, as refrigerants should not be handled by homeowners. They can inspect the system for leaks, repair any damage, and recharge the refrigerant if necessary.
4. Calibrate the Thermostat: Verify that your thermostat is calibrated correctly and set to the appropriate temperature. If you notice any issues with your thermostat, such as inaccurate temperature readings or erratic behavior, consider replacing it.
5. Thaw the Coil: Once the system is turned off, you can help speed up the thawing process by using a hairdryer on a low heat setting to gently warm the frozen coil. Avoid using any sharp objects or excessive force to remove ice, as this can damage the coil.

If you’re unsure about DIY repairs or encounter complex issues, don’t panic! Reach out to a certified HVAC technician with the know-how and proper training to unthaw the heat pump evaporator coil.