Heat pumps are extremely efficient and an excellent option for heating your house in the winter and keeping it cool all summer long. As with a standard central AC unit, heat pumps can sometimes start to freeze up in the summer for a variety of reasons. It is normal for ice to develop on the heat pump itself in the winter, which is why all heat pumps need to occasionally run in defrost mode to melt the ice and thaw out the unit. However, a heat pump system that freezes up inside or outside during the summer when the system is in cooling mode can be a sign of a serious failure. Today we’re going to discuss some of the reasons a heat pump can freeze up in the summer and what can be done to fix them.

Cold Temperature

Running a heat pump system when the outdoor temperature is too cold can easily cause the evaporator coil inside your house to freeze up. When the evaporator coil freezes, you may also start to see ice or frost building up on the refrigerant lines outside the house that connect the heat pump to the evaporator coil. You really should never need to run your heat pump any time the outdoor temperature is around the same as your desired indoor temperature.

If you ever run your heat pump when the outdoor temperature is below 62 degrees, the system is almost certain to quickly start freezing up. Running the heat pump on cooling mode in cooler weather causes the refrigerant pressure to drop, which results in the refrigerant becoming much colder and leading to condensation on the evaporator coil starting to freeze.

Airflow Issues

The most common reason that a heat pump system will freeze up inside your home is because the system isn’t getting sufficient airflow for some reason. This usually happens because the air filter is clogged restricting how much warm air can be pulled into the system by the blower. As such, we’d always recommend replacing your air filter as the first step should your system ever start freezing. You should also make sure that all of your vents are open and nothing is obstructing them as this can also prevent the system from getting proper airflow.

Restricted airflow can also happen if the blower begins wearing out or malfunctioning, in which case you’ll need to have a technician replace or repair it. If the blower isn’t cleaned regularly, it can also get clogged with dust so that it can’t work properly. This is something you can easily avoid by having your system maintained every spring and autumn.

Dirty Evaporator Coil

The evaporator coil can also quickly start freezing up if it is coated in lots of dirt and dust. The layer of dust acts like an insulator that blocks the warm air coming into the system from reaching the evaporator coil. When there isn’t enough warm air blowing directly onto the coil, the refrigerant will absorb little to no heat. As such, the evaporator coil can quickly become cold enough that it begins to ice up. A dirty evaporator coil is also something you can easily prevent with annual maintenance.

Low Refrigerant Charge

Heat pumps will also quickly start to freeze up if there isn’t enough refrigerant in the system. When the refrigerant level is low, the pressure in the system decreases. This again causes the temperature of the refrigerant to also drop leading to the evaporator coil becoming much colder and starting to freeze. The only way to know if the system is low on refrigerant is to have a technician check the refrigerant charge. If the refrigerant is low, it usually indicates that there’s a leak somewhere in the system that will need to be fixed before additional refrigerant is added.

Malfunctioning Thermostat

Your heat pump could also be freezing due to an issue with your thermostat. Setting the thermostat to too low of a temperature as the system will run for much longer causing the evaporator coil to get much colder and potentially start freezing. Thermostats can also malfunction or not accurately read the indoor temperature leading to the system again running longer and cooling the air in your home down to the point where the evaporator coil begins freezing.

Louisville’s HVAC Full Service Team

Element Air LLC specializes in HVAC maintenance and repairs, and we can help if you have a heat pump that continually freezes or any other issues with your cooling or heating. We service all brands and models of heat pumps, and we also work on ACs and furnaces. Contact us today if you need a heat pump inspection or to schedule any other HVAC service in the Louisville area.

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