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What to Do When My Heat Pump Is Frozen?

What to Do When My Heat Pump Is Frozen?

  • Heating
Learn what to do when your heat pump is frozen, how to prevent future freezes, and what happens if you neglect your frozen heat pump.

Heat pumps are an efficient and eco-friendly way to keep your home warm during the colder months. However, they are not immune to issues, and one common problem homeowners encounter is a frozen heat pump. When your heat pump freezes, it can be a frustrating and uncomfortable situation. In this guide, we’ll explore the causes of a frozen heat pump, signs to look out for, consequences of leaving it unfixed, and most importantly, what steps to take when your heating system becomes an ice-cold headache. At McHales we specialize in prevention and professional heat pump repair and replacement. When your heat pump is frozen, contact us for expert service!

Common Causes

Understanding why your heat pump freezes is the first step in addressing the issue. Several factors can contribute to this problem:

  • Low Refrigerant Levels: Insufficient refrigerant can cause the heat pump to operate less efficiently, leading to freezing.
  • Clogged Air Filters: Dirty or clogged air filters restrict airflow, causing the heat pump to work harder and potentially freeze.
  • Sub-Freezing Temperatures: Extremely low temperatures can cause frost and ice buildup on the outdoor unit of your heat pump.
  • Malfunctioning Defrost Cycle: If the defrost cycle isn’t functioning correctly, ice can accumulate on the outdoor coils.
  • Blocked Coils or Vents: Obstructions around the heat pump can restrict airflow, leading to freezing.

Signs of a Frozen Heat Pump

Recognizing the signs of a frozen heat pump is crucial for timely intervention. Keep an eye out for these indicators:

  • Heat Pump Blowing Cold Air: If your system starts blowing cold air instead of warm, it may be frozen.
  • Ice Buildup: Visibly seeing ice or frost on the outdoor unit is a clear sign of a problem.
  • Fan on Heat Pump Not Working: If the fan isn’t running, it can lead to freezing issues.
  • Steam During Defrost Cycle: If your heat pump is producing steam while it runs its defrost cycle, your system is most likely frozen. 
  • Ice on Refrigerant Lines: Inspect the refrigerant lines that connect the indoor and outdoor units. Ice buildup on these lines is a telltale sign that your heat pump is frozen.

Consequences of a Frozen Heat Pump

Neglecting a frozen heat pump can result in several undesirable consequences:

  • Reduced Efficiency: A frozen heat pump operates inefficiently, causing higher energy bills.
  • Damage to Components: Prolonged freezing can damage the heat pump’s components, leading to costly repairs.
  • Uneven Heating: Your home may experience inconsistent heating, making certain areas uncomfortably cold.
  • Short Cycling: Your system may struggle to maintain the desired temperature if it’s too cold, leading to erratic cycling.

What to Do When My Heat Pump Is Frozen

Most heat pumps have a built-in defrost system. The defrost cycle is activated when the outdoor coil’s temperature is low enough to cause ice buildup. The reversing valve extracts heat from the indoor unit and releases it to the outside unit. If the defrost cycle feature isn’t functioning or is not effectively thawing your system, here are the steps to take:

  • Turn Off the Heat Pump: Shut off your heat pump to prevent further damage.
  • Thaw the Unit: Allow the ice to melt naturally, or carefully remove it using warm water (avoid using hot water to prevent damage).
  • Check Air Filters: Inspect and replace dirty or clogged air filters to ensure proper airflow.
  • Clear Obstructions: Remove any debris or obstructions around the heat pump to improve ventilation.
  • Restart the Heat Pump: Once the unit is thawed and the filters are replaced, restart the heat pump.


Prevention plays a pivotal role in ensuring the efficient and uninterrupted operation of your heat pump, especially during the cold winter months. Taking proactive measures to prevent freezing issues can save you from costly repairs and discomfort. To avoid future freezing issues, follow these tips:

  • Regular Maintenance: Schedule professional maintenance to ensure your heat pump is in top condition.
  • Keep Surroundings Clear: Regularly clear debris and snow from around the outdoor unit.
  • Replace Air Filters: Change air filters as recommended by the manufacturer.

When to Seek Professional Repair

If your heat pump continues to freeze despite taking preventive measures or if you encounter issues with the defrost cycle, it’s time to call in a professional heat pump repair service. Attempting to repair complex issues without the necessary expertise can lead to further damage. At McHales, we offer a wide variety of HVAC services including heat pump repair and replacement. To get your frozen heat pump serviced, contact us today!

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By Brenna Thirkell

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