Heat Pump Freezing Up? (10 Reasons Why Its Icing Up)

Anyone’s heat pump can freeze; it’s a very common situation for homeowners. If your heat pump is freezing up, you’ll want to know how to deal with it right away. It would be best if you understood how heat pumps work to get the best results.

All homeowners should read this guide to understand what causes a heat pump to freeze up. That way, you can fix the problem quickly. Let’s begin!

Your heat pump can freeze up year-round- not just in the winter. It’s a widespread problem for homeowners everywhere. If this happens, your unit won’t run effectively.

The system freezes when the coil gets too cold, hits warm air, and creates condensation, which then freezes on the outside of the coils. There are 10 main reasons why this can happen:

Clogged Air Filter

Clogged air filters cause many problems in an air pump. If left alone for too long, they start collecting debris. Once clogged, the dust blocks airflow and moisture in the unit. With the extra moisture, condensation and freezing can occur.

You will want to replace or clean the filter as soon as it’s full of debris. Then, run the heater to melt the frost.

Too Dirty Evaporator Coil

Refrigerant travels through the evaporator coil. It’s responsible for taking heat in and out of the home. When the coil is too dirty, it can’t transfer heat efficiently and may freeze up. You’ll want to shut down the unit, then pour warm water over the frost.

Poor Airflow

Poor airflow is caused by clogged filters, blocked vents, or a broken blower. When there’s no airflow, the coils are much more likely to freeze up. With a heat pump icing up, you want to make sure you increase the airflow in the unit’s coils.

Low Refrigerant

When low on refrigerant, the heat pump can freeze. Most of the time, this is due to leaks. You’ll want to check for weak joints, which is where the liquid is most likely to escape.

Rattling pipes is a sign of low or empty refrigerant. When you hear rattling or seek leaking, power down the unit, then contact a professional.

Faulty Blower Motor

When your blower motor fails, it can cause a lot of damage and lead to the heat pump condenser coil freezing. As a result, you might notice the fan starting and stopping consistently or running at a slower speed. It’s important to take care of this problem right away- you’ll need a replacement.

Dirty Fan Blades

When the fan blades are dirty, the unit will take more power to run and may struggle with its airflow levels. Moisture can also be trapped inside the unit, which creates condensation on the heat pump. The condensation might even freeze.

Freezing Rain Leading To Ice Build Up

If freezing rain touches a cold heat pump, it’s going to stay there. It’s very easy for ice to build up on the unit in this way. You want to consider getting a heat pump cover for ice and snow to prevent this from happening.

Drain Blockages

When the drains inside the unit become blocked, they fill up with moisture- leading to condensation. You’ll want to make sure the heat pump doesn’t have an excess of water inside of it. A professional can remove these clogs for you.

Stuck Reversing Valve

When the reversing valve is stuck, your machine won’t have good airflow, and the unit won’t change between heating and cooling systems. You can find this valve by the compressor of the heat pump. It’s difficult for people to fix alone, so you’ll want to contact a pro.

Lack Of Maintenance

Finally, you might’ve been neglecting your heat pump. It’s a good idea to have a professional come out and inspect the heat pump every few years- more often if you’ve had issues with it in the past. They’ll find the worn-out parts and replace them for you.

Can A Heat Pump Work In Below Freezing Temperatures?

Can a heat pump work below freezing? These units run well until the temperature goes below 40 degrees Fahrenheit. If it goes below 30 degrees, its performance starts to suffer even more, until it’s not effective at all.

If you know an icy spell is on the way, it’s important that you have a backup heating system in place. Your unit could freeze and stop running well, when you need it the most.

Popular Heat Pump Brands & Why They Freeze Up

There are three leading heat pump brands (see our top picks here) on the market today. They each freeze up, but for different reasons.

Lennox Heat Pump Freezing Up

If your Lennox heat pump is freezing up, it’s for one of the following reasons:

  • The filter needs to be cleaned
  • It has low refrigerant
  • The evaporator coil is dirty
  • The fan is too slow

If you can’t determine the problem, a professional would be happy to take a look for you.

Payne Heat Pump Freezing Up

When your Payne heat pump is freezing up, it’s probably because of a dirty air filter. However, it may also have a sealed system leak. This is obvious; freezing only happens in one place on the machine, but it’s a costly fix that requires an expert.

Trane Heat Pump Freezing Up

When a Trane heat pump is freezing up in summer, you want to take care of it immediately. The most likely cause is a refrigerant leak, which requires a specialist to fix. You’ll notice leaking around joints on the pipes.

Should I Cover My Heat Pump To Protect It From Ice Or Snow?

You do not want to cover your heat pump! It’s designed to run all year long, and covering it could cause damages. The unit needs to be in the open so that it can release the exhaust. Plus, the unit takes in outside air to run.

During the winter, you’ll want to check on the heat pump often and remove excessive amounts of frost. Your unit should have a defrost mode, which melts the snow and ice automatically. Overall, there isn’t a need for a cover.

People Also Ask (FAQ)

Why do Geothermal heat pumps freeze up?

When warm air hits a cold coil, condensation appears. When the outside of the heat pump is already cold, the condensation is likely to freeze. This issue can happen any time of year- even in the summer.

Should I turn my heat pump off in extreme cold?

It’s best that you allow your heat pump to run all of the time. However, you should turn it off if it gets below 20 outside. Some machines have an emergency heating mode that you can use instead of shutting it down.

Why won’t my heat pump go into defrost mode?

The problem could come from malfunctioning sensors in the unit. Or, a valve that is stuck in reverse can also make this happen. Either way, you should have a pro come take a look.

What temp should I set for my heat pump in winter?

Most people prefer to have their heat pump set to 68 degrees F in the wintertime. This temperature keeps you comfortable without forcing the unit to run constantly and running up your bills.

Should I run my heat pump on auto or heat?

It’s best to avoid auto mode. Instead, switch it over to Heat or Cool. Auto runs during cool summer nights and warm winter days, which would use high wattage and make you uncomfortable.


To summarize, the main cause of freezing in your heat pump has to do with excessive amounts of moisture building up in the unit. You should check it for clogs and leaking before doing any other troubleshooting.

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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

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Midea U Shaped Window Air Conditioner

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