8 Easy Fixes For a Frozen Heat Pump (Solutions Explained)

Josh Mitchell

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Josh Mitchell

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Holly Curell

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I've had my fair share of heat pumps freezing up, usually just when I need them most, so I know firsthand how frustrating it can be.

Here, I'll explain why your heat pump freezes - from low refrigerant levels to poor airflow and external factors like the weather.

More importantly, I'll share practical tips and solutions to fix the issue and keep your system running smoothly.

Let's unravel this frosty mystery so your heat pump unit will run like clockwork regardless of the weather.

8 Simple Solutions For a Heat Pump Freezing Up

Understanding and maintaining your heat pump is crucial, especially in extreme weather conditions.

It's a common issue when heat pumps freeze, but it's often fixable.

Regular maintenance and timely fixes prevent freezing and ensure your heat pump works efficiently, ensuring it doesn't consume more energy than necessary, and you can have lower energy bills.

1. Manually Defrost Your Heat Pump

This is one of the most common issues I have seen. It usually happens in winter when the temperature is low and you have frozen coils.

What Homeowners Need To Do:

  • If you notice ice on your pump, run warm water on the sides of the heat pump. 
  • Make sure not to use a sharp object to crack ice, even if there’s a thin layer of ice formation. This can damage your pump.
  • You can also try the defrost mode on your pump. When warm air hits the outdoor coil during the manual defrost process, it helps in melting the ice more efficiently.
  • Switching your heat pump to cooling mode for a short period can help melt the ice during manual defrost.
  • Turn on the fan setting so there's warm air blowing for about an hour.
  • If the outdoor temperature is very low, and this doesn’t help, you can try to reverse the valve to air conditioning mode, which turns the outdoor fan off and turns the outdoor evaporator into a condenser.
  • This melts the ice as it circulates air through the outdoor coil.

2. Inspect and Clean The Coils

Dirty coils can lead to inefficient operation and freezing. I've seen many units freeze up due to neglected coils.

What Homeowners Need to Do:

Safely clean the coils with a soft brush and coil cleaner. This should be a routine maintenance task performed at least bi-annually.

3. Check The Refrigerant Levels

Proper refrigerant levels are vital for heat pump work efficiency, and low levels are a common cause of freezing.

What Homeowners Need to Do:

This requires an HVAC system professional. If you suspect an issue, call a technician to check and refill it to ensure optimal refrigerant flow.[1]

4. Install a Defrost Cycle

A defrost cycle is a game-changer. It periodically melts ice on the coils, preventing buildup.

What Homeowners Need to Do:

Turn on the defrost cycle. It temporarily produces hot air to melt the ice, ensuring the heat pump doesn’t freeze.

If your unit lacks this feature, consider an upgrade. A professional can easily install a defrost cycle.

5. Improve The Airflow Around The Heat Pump

Adequate airflow is vital. I've seen units freeze simply because a piece of furniture was blocking a vent.

This causes the compressor coils to a lower temperature, making the heat pump indoor coil freeze.

A bad airflow in the air handler also happens because of obstructions in the ductwork or clogged air filters.

What Homeowners Need to Do:

Ensure all air vents are unblocked and open, as blocked return vents can prevent your heat pump from running smoothly.

Also, ensure the outdoor unit has at least 18 inches of clearance all around.

6. Insulate Any Exposed Pipes

Regularly changing the insulation on your pipes, especially before the winter season, can significantly reduce the risk of freezing.[2]

I've personally seen how effective this can be in extending the life and efficiency of a heat pump.

What Homeowners Need to Do:

Use foam insulation to cover exposed pipes. This is an easy DIY task that can prevent many cold air issues.

Ensure that all exposed pipes are well-insulated to prevent them from freezing in cold weather conditions.

7. Fixing a Failed Compressor

A compressor can fail because you didn’t maintain the heater for a long time.

What Homeowners Need to Do:

This is a complex one, and my advice is to get an HVAC professional for heat pump repair. Here’s which steps to follow:

  1. 1
    Diagnose the Problem: Confirm that the compressor is the issue. Some symptoms to look for include the system not cooling, making strange noises, or tripping the circuit breaker.
  2. 2
    Power Off the System: Before any work, ensure the system is completely powered off for safety.
  3. 3
    Check Warranty and Documentation: If the unit is still under warranty, contact the manufacturer or installer for repair or replacement.
  4. 4
    Hire HVAC technicians: Due to the complexity and the need for specialized tools and knowledge (including handling refrigerants, which is regulated).
  5. 5
    Replacement vs Repair: The technician will assess whether the compressor can be repaired or needs to be replaced. In many cases, replacement is the more viable option.
  6. 6
    Install New Compressor: If replacement is necessary, the technician will remove the old compressor, install a new one, and handle the refrigerant according to legal and safety standards.
  7. 7
    System Test: After installation, the system will be tested to ensure it operates correctly and efficiently.

8. Schedule Regular Maintenance Checks

A well-maintained heat pump is essential for optimal airflow and efficiency, reducing the risk of ice forming and freezing up in winter.

What Homeowners Need to Do:

A thorough inspection done every 12 months can identify potential issues that might lead to the heat pump freezing. 

Also, keep the area around the unit clear of debris and foliage.

What Causes a Heat Pump to Freeze Up? (Advice For Summer Vs Winter)

You should keep the heat pump running smoothly in both summer and winter. However, many homeowners think pumps can freeze only in winter.

In summer, your heat pump acts like an air conditioner, and issues like dirty coils can cause freezing up in summer, similar to a traditional AC unit.

Moreover, high humidity in summer can impede the heat pump's efficiency in absorbing heat from the outdoor air, leading to freezing issues.

In winter, the heat pump extracts heat from the outside air, but freezing conditions can lead to ice forming on the unit.

Here are all the reasons that cause heat pump freeze up:

  • High Humidity: In summer, high humidity can lead to excessive moisture around the heat pump’s evaporator coil, which increases the likelihood of freezing.
  • Obstructed Airflow: Both in summer and winter, blocked airflow can cause the heat pump to overwork and freeze.
  • Low Refrigerant Levels: Reduce the heat pump's ability to transfer heat, which can lead to freezing in both seasons.
  • Dirty Coils: More prevalent in summer due to increased usage, as dirty coils hinder efficient heat exchange, causing freezing.
  • Malfunctioning Defrost Control Board: In winter, a faulty defrost control board can fail to initiate the defrost cycle, which leads to ice buildup, and the pump stops air blowing.
  • Reversing Valve Failure: This issue can occur in both seasons, causing the heat pump to stick in one mode and potentially freeze.
  • Clogged Air Filter: Common in both seasons, when a clogged air filter restricts airflow, increasing the risk of freezing.
  • Blower Motor Malfunctioning: A malfunctioning blower motor can lead to inadequate airflow and freezing in both summer and winter.
  • Freezing Rain and Weather Conditions: Primarily a cold weather issue, freezing temperatures can cause ice accumulation on the outdoor unit, leading to freezing.
  • Clogged Drain: More likely in summer due to higher humidity, when increased condensation freezes and can lead to clogged drains, causing water backup and potential freezing around the coils.
  • Leaves, Grass, Sticks, and Debris Around the Outer Unit: Common in both seasons because debris around the unit can obstruct airflow and cause freezing.
  • No Regular Maintenance: In summer and winter, lack of regular maintenance can lead to various issues, including freezing due to undetected problems.

How to Prevent Ice Build-Up on Heat Pump

Here’s how to prevent ice buildup on your heat pump.

Remove Excess Snow in Wintertime

Remove excess snow, or you risk ending up with a frozen coil. Here's what you should do:

  1. 1
    Regular Monitoring: Frequently check your heat pump, especially after snowfall or freezing rain. Ice tends to build up under these conditions.
  2. 2
    Safe Snow Removal: Gently remove snow from around the unit. Use a soft brush or broom; avoid hard tools that could damage the unit.
  3. 3
    Clear a Perimeter: Maintain a clear space of at least 18 inches around the heat pump. This ensures adequate airflow and reduces the risk of snow drifting against the unit.
  4. 4
    Avoid Piling Snow Near the Unit: When shoveling or plowing your property, be mindful not to pile snow near the heat pump.
  5. 5
    Inspect for Ice Dams: Check for ice dams that can form and block the drainage, leading to water backing up and freezing.

Use The Defrost Mode If Needed

Most modern heat pumps have an automatic defrost option.[3] This function reverses the refrigeration cycle, sending warm refrigerant through the outdoor coils to melt ice.

You should perform regular checks to ensure the defrost option is functioning correctly. Ineffective defrost cycles can lead to excessive ice buildup.

The defrost cycle should activate periodically and only run as long as necessary to melt the ice. Overly frequent or lengthy cycles can indicate a problem.

If you suspect the defrost function isn’t working correctly, have HVAC professionals inspect and calibrate it. Incorrect settings can lead to insufficient defrosting.

The technician should check sensors and related components, as a malfunction in these parts can hinder the defrost cycle.


How do I identify a ‘frozen’ heat pump?

To identify a frozen heat pump, look for ice or frost buildup on the outdoor unit, especially around the coils. The heat pump may also stop having an effective heat mode or make unusual noises.

Can a Heat Pump Get Stuck in Defrost Mode?

Yes, a heat pump can get stuck in defrost mode due to faulty sensors, control boards, or wiring issues, leading to inefficient heating and potential damage.

Can You Pour Warm Water on a Frozen Heat Pump?

Yes, you can pour warm water on a frozen heat pump. Pouring warm water can temporarily melt the ice, but it's not recommended as a long-term solution. It can cause rapid temperature changes, potentially damaging the unit.

Do heat pumps work in freezing temperature conditions?

Yes, modern heat pumps are designed to work efficiently in freezing weather, but their efficiency can decrease as the outside temperature drops significantly below freezing.


  1. https://www.airexpertsnj.com/blog/how-do-i-know-if-my-heat-pump-needs-freon/
  2. https://www.forbes.com/home-improvement/plumbing/how-to-insulate-water-supply-pipes/
  3. https://www.coolzoneair.com/blog/hvac/the-heat-pump-defrost-cycle-explained/
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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.

My Favorite Home Appliance?

Midea U Shaped Window Air Conditioner

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