Why Is My Heat Pump Freezing Up: Three Causes

If you notice a bit of ice on your heat pump during the mild California winter, it’s usually not a cause for alarm. Your heat pump features a defrost mechanism designed to prevent the buildup of an excessive amount of ice. However, if the heat pump doesn’t defrost completely or becomes encased in ice, it’s time to call the professionals.

At Inland Empire Comfort Air Conditioning and Heating, we’re Riverside’s heat pump services experts. We understand that even though temperatures don’t plummet in Southern California the way they do in other areas, you still rely on a working heat pump to keep you warm on cooler days.

If searching the internet for “why is my heat pump freezing up?” isn’t yielding the answers you need, we’ve compiled three of the most common reasons your heat pump may be malfunctioning when you need it most.

Why is My Heat Pump Freezing Up?

Heat pump freezing occurs when the vaporized refrigerant condenses moisture on the outside coil of the pump. When the temperature outside drops below freezing, the condensation turns into a layer of ice on the coils. The heat pump kicks on its automatic defrost feature, melting the thin layer of ice and allowing the heat pump to continue functioning properly. Without the defrost cycle, the layers of ice build up, and soon your heat pump stops working. If your heat pump builds up too much ice, something is wrong.

Reasons For a Frozen Heat Pump

1. Dirty or Clogged Air Filter

As with any HVAC system, dirty air filters are often the culprit behind a frozen heat pump. Air filters keep dust, pet hair, and other debris from getting into the mechanisms of your HVAC system. When the air filter gets clogged, it blocks airflow and traps moisture, which in turn hinders the functionality of your heat pump. 

If your heat pump freezes up, the first thing you should do is check the air filter. Air filters should be changed at least every three months. If you have pets, we often recommend changing your filter monthly. If installing a clean filter and running the defrost cycle still doesn’t melt the ice, call your local HVAC experts.

2. Lack of Refrigerant

It’s important to periodically check the refrigerant levels in your heat pump, as it’s a vital component to both the heating and cooling cycles of the unit. If you notice unusually low levels of refrigerant, this could mean you have a leak. It’s normal to lose a minimal amount of refrigerant during the evaporation process, but if your heat pump runs too low on refrigerant, it may cause the unit to freeze. 

Refrigerant leaks happen with the wear and tear of everyday use, as well as because of faulty valves, weak joint soldering, loose fittings, or accidental punctures. These issues may often be avoided by regular maintenance visits from HVAC professionals. Your HVAC professionals should provide routine heat pump maintenance services to help keep your heat pump running smoothly all year round. 

 3. Dirt Buildup on Your Evaporator Coil

In a heat pump, refrigerant flows through the evaporator coil, warming the cold air from the outside coils before the blower fan moves the heated air into your home. If your evaporator coil has a buildup of dirt and grime, it impairs the ability of the unit to transfer heat. If the air flow is impeded, the heat pump may freeze up. 

If you see ice forming on the evaporator coil, turning off your heat pump and gently pouring warm water over the coils should melt the ice. If the heat pump freezes up again, call your local Riverside heat pump repair and maintenance service. 

Call Us For 24-Hour HVAC Service in Riverside

At Inland Empire Comfort Air Conditioning and Heating, we understand that the safety and comfort of your home is essential. That’s why we hire the best in the business. Our professionals not only know the basics of how to check if your heater is working, but also know the most efficient, effective, and affordable way to remedy the issue with as little stress as possible. 

From answering questions like “why is my heat pump freezing up?” to performing regular maintenance to ensure optimal HVAC performance, our trained and experienced technicians do it all.



When you choose Inland Empire Comfort Air Conditioning and Heating, you know you’re in good hands. Call us today at (951) 336-1892 to schedule a consultation for your heating and cooling systems in Riverside, CA.