What To Do When Your Heat Pump Coil Freezes

Becca Stokes
Written by Becca Stokes
Updated July 29, 2021
A woman wrapped in a blanket checking her phone
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Learn how much ice is OK and when it's time to thaw things out ASAP

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You love your heating pump system most of the time. It keeps you cool in the summer and warm throughout a mild winter. But sometimes, extended cold weather causes your heat pump’s coil to freeze, leaving you in the cold. A frozen evaporator coil is a fairly common heat pump problem, and luckily it’s usually easy to solve. Let’s break down what causes a frozen heat pump coil, what you need to do to fix it, and how to stop it from happening in the first place.

What Is a Heat Pump?

A popular way of heating (and in some cases cooling) homes located in mild climates, a heat pump uses thermal energy to change the temperature indoors. A heat pump system is installed outside your home and is a popular alternative to other forms of heating the home that might use fossil fuels.

Why Do Heat Pumps Freeze?

If you spot a little bit of frost on your heating coil the next time you check out your heat pump system, don’t panic. A bit of buildup is totally normal. Frost forms because heat pumps use refrigerant, which becomes a gas, and then, as it moves back outside, condenses into moisture.

Most heat pump systems are designed with this in mind. They have built-in defrosting mechanisms to prevent excessive amounts of ice from forming. But when that mechanism fails, ice starts to build up.

Here are the most common reasons you will find too much ice on your heat pump coils:

  • Dirty air filters, coils, and/or fan blades

  • Damaged sensor

  • Failing blower motor

  • Low refrigerant levels

  • System installed on uneven surface

How to Spot Frozen Coils

Finding frozen coils involves, well, going outside and looking for them. If you see any amount of ice greater than you might see on grass on a spring morning, you need to remove it.

How to Remove Ice From Frozen Coils

Once you’ve confirmed that ice is the problem, here’s how to proceed with removing the ice from your heat pump’s coils. 

1. Turn off your heat pump

2. Remove what ice you can using a cloth and protected hands. Do not use sharp tools

3. Pour warm water over the ice until it melts

4. If ice buildup persists, contact an HVAC professional near you who can help.

How to Prevent Ice Buildup

A techinician checking a heat pump
Eakrin - stock.adobe.com

You might have noticed a common theme when it comes to the most common reasons your heat pumps are freezing: Dirt. To keep your pump clean and working its best, schedule an annual maintenance check-up with your HVAC professional. The cost of heat pump maintenance and repairs on average is $372.

One of the best ways to avoid frozen coils on a heat pump involves maintenance. Because multiple issues can cause frozen coils, keeping the heat pump in good shape via annual service appointments ensures that the entire system is operational and limits the effects of wear and tear. Maintenance also helps keep the system free of dirt buildup.

In addition to maintenance, follow these tips to keep the system running well:

  • Don't let ice and snow accumulate on the outdoor unit. After snowstorms and extreme weather, brush it off when you’re out clearing the sidewalk.

  • Secure gutters above the outdoor unit. Avoid letting water drip out of the gutters and onto the unit to prevent water from leaking into the coils and freezing. An outdoor unit encased in snow and ice can also prohibit airflow, which leads to frozen coils.

  • Level the unit. The outdoor unit must be 100% level; any tilting can restrict airflow and hinder the system from draining moisture properly.

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