Heat Pump Is Icing Up In The Winter

The outdoor unit of a heat pump will always be exposed to the elements. During winter, it is common to see bits of frost on the surface. This isn’t usually a cause for concern. However, a large volume of ice is a different story. A heat pump is icing up in the winter may interfere with the operation and cause equipment damage. When temperatures drop, be vigilant in observing the state of the heat pump. Find out what is tolerable and what is not. Armed with knowledge, you will be able to act fast whenever necessary.

Heat Pump Is Freezing Up In The Winter

Make it a habit to check the heat pump for signs of ice. This is particularly important during days of harsh winter weather. Don’t panic if you see it frosted over as the system can still work despite how it looks. In fact, this is a regular sight in northern regions throughout the colder months. On the other hand, those who live in places with mild winters may not be familiar with this phenomenon. They might be surprised if it happens after a snowstorm, for example. This article provides information about why it occurs and what homeowners can do about it. 

Why Is My Heat Pump Icing Up In Winter?

image of couple feeling chilly due to frozen heat pump

The main reason why heat pumps freeze in winter is typically a faulty component. If everything were working correctly, then icing can be kept to a minimum. If something is wrong with the system, then ice can build up to unmanageable levels. Sometimes the problem can be fixed with a few easy steps. In most cases, however, this will require the immediate attention of an HVAC professional. Licensed technicians can make a home visit for inspection and repair. They can also be scheduled for regular maintenance to avoid heat pump problems and prolong the unit’s lifespan. 

Heat Pump Defrost Cycle

Since freezing is so common, modern heat pumps are now equipped with a defrosting function. Engineers have added this so that the system can take care of itself. Homeowners won’t have to worry at all. The defrost cycle can kick in automatically once the system detects icy conditions. It can also be activated manually. In a nutshell, it works by reversing the valve to turn on air conditioning mode. The outdoor evaporator becomes a condenser and the outdoor fan turns off. All of these should heat up the refrigerant and melt the ice around the coils. 

Signs Of A Problem With Your Heat Pump

The sight of ice on a heat pump is not pleasant. You may get the urge to call a service technician for assistance right away. This could be a prudent course of action if certain conditions are present. For example, if you see the entire heat pump frozen over, then you will definitely need help in reversing the situation. A technician can also make sure that the system does not suffer from major damage. Ice should be a temporary development. If it persists for a long time, then something is wrong with the heat pump. Technicians can determine why the defrost cycle is not getting activated. You can also call for help if air is not being drawn into the fins of the unit.

What To Check If The Heat Pump Unit Is Freezing Up

1. Clogged Air Filter

homeowner replacing heat pump filter

When you see a frozen heat pump, the first thing to check is the air filter. Filters have a limited service life lasting for only a few months. If you leave them on longer than this, then they will catch so much dirt that air won’t be able to pass through. Clogged air filters also trap moisture which can freeze in low temperatures. Make sure to install new filters every 1-3 months to avoid this problem. If your house has a lot of pets and dust, then try to do it as often as you can. 

2. Low Or Empty Refrigerant

The heat pump won’t be able to work without refrigerant. This substance is responsible for absorbing heat outdoors and moving this indoors. If there is a leak, then the amount of refrigerant flowing across the coils will be insufficient to keep the system going. The problem may be due to a failed valve, a weak solder joint, a punctured tank, or unsecured fittings. A technician can find the leak and put a stop to it. More refrigerant can then be added to let the system return to normal. 

3. Filthy Evaporator Coil

Refrigerant moves within the evaporator coils of the outdoor unit. Here it absorbs heat that gets pushed into the home during the colder months. If the coils are dirty, then the process of heat transfer will be impaired. They can even freeze over time. Check the coils from time to time to see if a thick layer of dirt has built up and clean them quickly. If you see ice on these coils, then turn off the heat pump right away. Melt this by pouring warm water on the coil surface. If the problem reoccurs frequently, then call a professional for assistance. 

4. Faulty Heat Pump Blower Motor

outdoor heat pump unit

The blower motor controls the fan blades. If this is not working properly, then several problems may ensue including a frozen unit. Listen to the motor to find out whether it is stopping intermittently or not moving at all. These may require a motor replacement by a qualified HVAC technician. 

5. Dirty Heat Pump Fan Blades

Even if the blower motor is working fine, you can still experience trouble due to dirty fan blades. They may not be able to move as well as when they are clean. This compromises the airflow in the system and reduces exhaust output. Moisture can also get stuck and freeze up when the temperature plunges. Homeowners should not attempt to replace or clean the fan blades. Let the professionals handle this delicate component to avoid sustaining damage. 

6. Wintertime Neglect

There are various types of heat pumps. Some of them work better in cold weather than others. Frozen units may simply be due to their inherent limitations. You can discuss the matter with your HVAC contractor to learn more about this. 

Another thing to check is the stability of the heat pump base. It should be absolutely parallel to the ground. Tilting may result in trapped moisture which always has the probability of freezing. 

Lastly, make sure that gutter flow is far from the unit since this can trigger ice formation. Be vigilant in checking for ice on and around the unit. Deal with it immediately, alone or with the help of HVAC professionals. 

When To Call A Professional HVAC Contractor 

image of HVAC contractor performing heat pump tune-up

Homeowners can do a lot to minimize ice on heat pumps. For example, they can remove leaves and debris from an outdoor unit for better airflow. However, the solution is not always straightforward. It is better to let the professionals handle the matter for a quick resolution. Better yet, make it a point to schedule annual HVAC maintenance. This will prevent the most common issues and prolong the system’s lifespan.  


Small amounts of ice can quickly appear and disappear on heat pumps during winter. This is not a cause for alarm. Massive volumes of ice are another matter since performance, efficiency, and reliability may be compromised. Check the key components listed above to determine the cause of the anomaly. Call a trusted HVAC contractor for assistance.