Heat Pump Freezing Up In Winter – What To Do?

Your home might turn into an ice lounge if your heat pump freezes up in winter. So, what can you do to fix the issue? And, what causes this problem? Here’s what HVAC experts have to say:

There's no need to panic should your heat pump ice up. Let the defrost function do its job until it unfreezes. This function gets triggered once the temperature drops to 32 degrees and lasts for about 10 to 15 minutes. 

Is it common for a heat pump to freeze in winter? And can you melt ice manually if the defrost mode stops working? We’ve covered these questions and others you might have in mind below. So, read on to learn more.

Residential air conditioner unit in the snow in winter, Heat Pump Freezing Up In Winter - What To Do?

What Causes Heat Pump To Freeze Up In The Winter?

A heat pump develops an ice coating because of the condensation freezing in the outdoor coil during winter. It’s inevitable, so there’s a defrost cycle. 

When Is Ice Build-up A Problem?

Ice build-up becomes a problem when it blocks the airway; it prevents the system from expelling cold air, damaging the coils, fan blades, and refrigerants. It’s advisable to stop the HVAC operation when that happens. 

Signs of excessive ice include: 

  • The fins cannot pull air
  • Frost covers the entire unit
  • The heat pump has been encased in ice for a few days
  • The inner coil has an ice coating

What To Do If Your Heat Pump Freezes Up?

Frozen heat pump

As we mentioned earlier, leave the frost to the defrost function. All heat pumps have this mode to make sure things run smoothly. Once the temperature sensor detects that the temperature drops too low, it will activate.

The system directs the refrigerant to the frozen coil outside for 10-15 minutes to thaw ice. Usually, the heat pump goes on defrost mode after every 35- 40 minutes, or as needed during the winter. 

What If The Defrost Cycle Isn't Working?

When the defrost cycle isn’t working, there are more than a few reasons this happens.

1. Clogged Air Filters

Ice on coil cooler of dirty air conditioner

These prevent the warm air from reaching the coil, so the defrost function won’t work. Check if the air filter has a build-up and replace it if needed. 

2. Defective Reverse Valve

This controls the system’s ability to switch to defrost mode. So, if it gets damaged, the unit won’t defrost.

3. Broken Outdoor Fan

When this breaks, it impedes the release of hot air, which causes frost to accumulate. 

4. Low Refrigerant

When this happens, it reduces the amount of heat that the defrost function produces, making it ineffective. 

5. Leaking Gutter

Water leaks trigger the defrost mode when it is unnecessary. And that can lead to a malfunction.

Call the HVAC repair service if the defrost cycle stops working. Avoid using the heat pump while it is frozen because it will cause the system to break down. 

Other Ways To Defrost Your Heat Pump

While waiting for the HVAC repair service to arrive, here are some things you can do to address the issue:  

  • Thaw it with a garden hose. First, turn the system off, then spray it with water until the frost melts. Don’t try to remove the ice with sharp objects (i.e chisel, hammer) as it can damage integral components.  
  • Run the heat pump on a “fan mode." The warm air it produces can help melt the ice. 
  • Pour hot water on the heat pump: Yes, you can pour hot, not boiling water over the unit. Drizzle it directly onto ice build-up.

Protect Your Heat Pump From Ice And Snow

To protect your unit from ice and snow, you must:

Build A Wind Barrier

Air conditioning and heating unit for a residential house

Plant shrubs or other perennial plants around your system. Place them 24 inches away from the heat pump as it needs plenty of space to maintain adequate airflow.

You may also opt for a privacy screen; it’s easy to install and best for concealing a heat pump. However, it is expensive. Also, never cover the unit.

Because your heat pump gets used throughout the year, covering it makes it a fire hazard. 

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Check Gutters Periodically

Broken or clogged gutters result in constant water leaks onto the outdoor unit, causing ice build-up. Inspect them from time to time to make sure they are working normally.

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How To Make Heat Pump More Efficient In The Winter

1. Avoid Turning Up The Temperature

Cranking up the temperature won’t heat your home any faster. It only increases your electric consumption.

What you need is a smart thermostat designed to adjust the setting as needed. It helps you maintain a comfortable temperature depending on how cold it is outside.

2. Reserve The Emergency Heat

A backup heating system uses natural gas or an electric strip. It supplies warm air efficiently during extreme cold, but save it for emergency situations.

3. Clean The Filters

Cleaning dirty air filter inside air conditioners

This allows air to flow smoothly, reducing the burden on your HVAC system.

4. Optimize The Air Direction

It's best to direct the airflow to an open space, away from any obstruction for the air to spread evenly.

5. Remove Fallen Leaves And Debris From Your Outdoor System

Debris and fallen leaves clog the compressor and the condenser coil. Also, it causes mold growth, so get rid of them ASAP. 

6. Insulate Your House

Insulate the doors, windows, attic, even ductwork properly. Seal all holes and possible air entry points. 

7. Double Up

If you live in an area with extreme temperatures, a dual fuel heat pump system might be perfect. With this, your heat pump gets paired with a furnace to back it up.

The former will do the initial heating, then it switches to the latter. This can save you a considerable amount of energy.  

Should I Use My Heat Pump All Winter?

Air conditioning machine frozen by the cold of winter

A heat pump goes on and off 2 to 3 times in an hour and stays on for 20 minutes. But when the temperature drops to 32 degrees, it might constantly run until it reaches a higher set temperature. No need to worry, as that’s how it’s supposed to work. 

Setting the heat pump at 68 to 72 degrees Fahrenheit during fall and winter provides optimal comfort, particularly if you have a large household. 

Does A Heat Pump Work Below Freezing?

Modern and high-performance heat pumps still work even at 25 degrees Fahrenheit, but some heat pumps become ineffective when the temperature drops that low.

To avoid inconvenience, choose a unit that handles below-freezing temperatures.  

What Is Emergency Heat On Heat Pump?

We’ve mentioned that the emergency heat is the backup or second stage heating. It turns on automatically when the temperature drops too low (30 degrees).

It works by bypassing the first stage of heating (heat pump) and uses either the gas or electric strip to operate. 

When To Use Emergency Heat?

Only use this for real emergencies, such as when your heat pump stops working, or it gets damaged during an ice storm. The red light indicates that the system is already on a gas or electric strip.  

Remember, emergency heat consumes a lot of energy, so you can expect an increase in your electric bill. That is why you should reserve it for emergency use only.

Follow The Scheduled Maintenance

Have your heat pump serviced periodically to detect problems with the coils, filters, refrigerant, loose belts, etc. Scheduled maintenance will help prevent them from getting worse and reduce unexpected breakdowns.

You want your system to provide reliable cooling and heating service. Fall and spring are the best time to schedule maintenance, right before the peak season arrives. 


Don’t panic if your heat pump freezes up in the winter. The system has a defrost function to fix this issue so it can maintain normal operation.

If the defrost cycle stops working, call your local HVAC repair service and try to thaw ice manually.

If you liked this post, you might also like: 

At What Temperature To Switch From Heat Pump To Furnace?

How To Protect Heat Pump From Freezing Rain And Snow

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