Troubleshooting Your Heat Pump: A Winter Freeze-Up Guide

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By Debarghya Roy

In this blog post, we will study the different causes, and preventive measures of heat pump freezing in winter in detail.

What Is Heat Pump Freezing?

Heat pump freezing occurs when the air present outdoors is transferred to the refrigerant source that extracts moisture from the cold air and accumulates on the refrigerant coils.

how to fix heat pump freezing up in winter

Causes of Heat Pump Freezing Up in Winter

To fix a heat pump from freezing up in winter, you need to understand its root causes. 

In this section, you will find sub-sections that describe problems related to insufficient airflow, dirty air filters, and reduced refrigerant levels, which could be detrimental to your heat pump’s health.

Insufficient Airflow

Insufficient airflow can lead to your heat pump freezing up in winter. 

  • Reduced air flow, due to dirty filters or blocked ducts, hinders heat transfer and causes ice to build up on the outdoor coil. This lowers performance and boosts energy costs.
  • Homeowners should routinely clean and replace air filters to keep optimal performance. 
  • Cleaning your ductwork every few years or as advised by a professional can enhance the efficiency of your system and reduce the chance of freezing up in winter.
  • Also, make sure that nothing is blocking your outdoor unit’s airflow. This includes taking away leaves, debris, and snow buildup during winter.

Dirty Air Filters

Clogged air filters bring an overload of dirt, dust and debris into the heat pump system. When this happens, airflow is blocked, leading to freezing up. 

The filter’s main job is to keep dust and debris away from the heat exchanger, so heating and cooling performance is optimal.

When air filters become dirty, a chain reaction starts. This restricts airflow, which causes the evaporator coils to freeze. 

If not taken care of, expensive components such as motors or compressors could fail.

To prevent these issues, be sure to maintain your heat pump regularly and change your filters as suggested by the manufacturer. 

If you live in an area with high humidity or near construction activities, consider changing your filters more often.

Reduced Refrigerant Levels

  • Heat pumps need the perfect amount of refrigerant to absorb and give off heat. A low charge causes the coils to freeze, making heating less effective. 
  • Not enough refrigerant affects performance, and can mess up parts in the long run.
  • Wear and tear can also cause leaks or aging damage in the refrigerant lines. Professional help is needed to check and refill the system.
  • Poor installation or leaks over time can lead to low refrigerant. 
  • With correct maintenance and quick repairs, your heat pump will keep running smoothly for longer.

How to Fix Heat Pump Freezing Up in Winter?

To fix your heat pump from freezing up during winter, checking and replacing air filters, removing ice from the outdoor unit, conducting a thorough inspection of the system, and calling a professional for repairs or maintenance are some of the solutions you need to explore. 

Let’s delve into each subsection to understand the best approach for your specific situation.

Check and Replace Air Filters

Maintaining the Efficient Heat Pump Flow

Periodic maintenance of heat pumps is essential to maintain proper airflow. This includes timely checking and replacing air filters to prevent freezing up. Dirty air filters reduce the airflow and make the heat pump work harder, which leads to refrigerant coil icing.

Follow This 6-Step Guide for Air Filters Check and Replacement:

Switch off the powerTo ensure safety, turn off the heat pump electricity supply before cleaning.
Find the filter locationUsually located in the indoor unit’s return air grill, carefully remove it.
Inspect the filter conditionLook carefully for any dust or dirt accumulation.
Clean or replaceEither replace or clean the filter with mild detergent soap or water.
Dry the filter thoroughlyMake sure it is dry before reinstalling it.
Reset the power systemAfter putting everything back into position, return all power settings to normal.

Working Parts Can Affect Health

Dirty filters reduce warm airflow indoors and can circulate pollutants like pollen, pet dander, and debris particles. These can trigger allergies and respiratory problems, affecting people’s health.

Neglecting Air Filter Replacement Has Consequences

A case study shows how regular maintenance of air filters helped save a family from costly heat pump emergencies due to freezing issues. Neglecting filter replacement led to significant damage. This required expensive repairs involving defrost controls changing parts and higher energy bills during winter cold snaps. Don’t wait for an emergency! Avoid frozen outdoor units like a pro.

Remove Ice from the Outdoor Unit

Ahoy there, if your heat pump turns into an ice box in winter, it can be quite uncomfortable.

Here’s a simple solution to avoid having to call a professional:

  1. Switch off your heat pump and let it thaw.
  2. After the ice has melted, check around the unit and remove any snow or debris blocking airflow.
  3. Use a low-pressure hose to remove any remaining ice.

Conduct a Thorough Inspection of the System

To guarantee the heat pump system works correctly, a thorough examination must be done. 

The inspection needs to be precise and all-inclusive for diagnosing the issue. 

Before discovering the reason why it iced up in winter, the system should be observed with skill and each component should be looked at carefully.

Here is a step-by-step guide to investigating your heat pump system completely:

  1. Start by turning off the power supply.
  2. Check if the air filters are clean.
  3. Look over the outdoor unit for any debris or obstruction that could block airflow needed for proper functioning.
  4. Inspect if there is leakage in refrigerant lines and fittings, including outside as well as inside units.
  5. Measure the ductwork throughout the home for damage or leakage that could restrict airflow and reduce performance.
  6. If problems remain, call in a professional serviceman for further analysis.

Call A Professional for Repairs or Maintenance

To keep your heat pump running through winter, call a professional to check it. They can spot any damage that may make it freeze. They can also clean the outdoor unit and replace any worn-out parts.

Preventive Measures for Heat Pump Freezing Up in Winter

To prevent your heat pump from freezing up in the winter, you can take several precautions as mentioned below,

Regular Cleaning and Maintenance

To make sure heat pumps work well and don’t freeze in winter, regular maintenance and cleaning are must. 

This includes inspection, fixing any damage or wear, and clearing any debris or ice on the unit. Here’s a six-step guide to keep your heat pump in good shape:

  1. Check coil fins for bends or damage. If any, straighten them with a fin comb.
  2. Clean or replace air filters each month. Dirty filters can block airflow.
  3. Clear away leaves, twigs, and other debris from the outdoor unit. Gently hose down to remove dirt from the coils.
  4. Check refrigerant level. Low levels may mean leaks that require professional attention.
  5. Lubricate blower bearings and motors to reduce friction and lengthen their lifespan.
  6. Test safety switches to avoid damages due to overload/output problems.

Investing in a Thermostat with a Defrost Cycle

A Thermostat with Automatic Defrost Mechanism is a great option to prevent Heat Pump freezing in winter. 

It gives optimal control and is energy efficient. It also eliminates the need for costly repairs.

Insulating Outdoor Pipes and Ductwork

In winter, you must insulate outdoor pipes and ductwork to avoid heat pump freezing. It also helps reduce energy costs and increase efficiency. 

Follow these steps to insulate outdoor pipes and ductwork:

  1. Gather the materials needed for insulation, such as fiberglass or foam pipe insulation, HVAC tape, foam board insulation, and cable ties.
  2. Clean all outside pipes and ductwork with a cloth or brush
  3. Cover the openings with caps or covers to guard against moisture.
  4. Measure the diameter of all exterior pipes and ducts to get an accurate length for cutting the insulation material. 
  5. Cut enough material to wrap around the pipes. Use a knife cutter, scissors, or blade to measure and cut precisely.
  6. Remove the adhesive from your insulation material and wrap it around the ducts or pipes. 
  7. Secure the insulation material in place using cable ties or HVAC tape if needed.
  8. Seal any joints with HVAC tape to avoid heat loss when you have wrapped all exterior pipes with your insulation material.

Protecting the Outdoor Unit during Winter

Winter means your heat pump’s external unit needs special care. Shield it from snow and ice to make it more efficient and add life. You can avoid damage to the compressor and other parts.

Protect your heat pump further with a waterproof covering. This prevents rust and corrosion from sleet or moisture. 

Make sure there’s enough clearance around the unit for air to flow.

You can also put a canopy above the unit. This shields it from harsh weather. But make sure it is installed high enough for airflow.

Invest in protection for your heat pump this winter – shields, coverings and a canopy. Extend its life and protect it from the cold. Don’t be stuck with a chilly repair bill!


A heat pump is a must-have for your home in the winter. Electric heaters can also help reduce frozen-up risk and lengthen your pump’s lifespan, despite being costly. Consult a licensed technician before repairs or replacements, as they are better trained to troubleshoot your system.

Frequently Asked Questions

Why is my heat pump freezing up in the winter?

A heat pump may freeze up in the winter due to a number of reasons including low refrigerant levels, dirty filters or coils, a faulty defrost system, or restricted air flow.

How can I fix a frozen heat pump?

To keep it running properly, you need to know how to stop it from freezing. Here’s the guide:

  1. Clean your air filter monthly.
  2. Clear two feet around the outdoor unit of any objects.
  3. Inspect and replace worn parts such as refrigerant, fan blades or thermostats.
  4. Get a professional technician to do an annual checkup.
  5. Install insulation in pipes and ducts.
  6. Keep your Heat Pump running, especially in low temps.

Can I prevent my heat pump from freezing up?

You can prevent your heat pump from freezing up by scheduling regular maintenance, cleaning the filters and coils regularly, ensuring proper airflow, and fixing any issues immediately.

How often should I schedule maintenance for my heat pump?

You should schedule maintenance for your heat pump at least once a year, ideally before the winter season starts.

Can I fix a frozen heat pump myself or should I seek professional help?

Unless you have experience and knowledge of HVAC systems, it’s best to seek professional help to fix a frozen heat pump. Attempting to fix it yourself may cause further damage and end up costing you more in the long run.

How much does it cost to fix a frozen heat pump?

The cost of fixing a frozen heat pump varies depending on the root cause of the problem. It may cost anywhere from a few hundred dollars to a few thousand dollars, especially if the issue requires replacement of parts or system components.

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