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F.H. Furr's Plumbing, Heating, Cooling & Electrical Insider Blog

What To Do When Your HVAC Freezes Up!


It is not normal for ice to form on your outdoor heat pump, and it is certainly cause for concern. There are several different scenarios on why this has happened to your HVAC system:


Bad Or Insufficient Air Flow

Air flow restriction is one of the biggest culprits and will cause the temperature of the system’s evaporator coil to drop below freezing.

  • Humidity in the air will collect on the coil causing ice to build-up and diminish the system’s cooling capacity.
  • Dirty air filters; collapsed, obstructed and undersized ducts; damaged blower motors; dirt build-up on the evaporator coil – all can seriously impede air flow.

Refrigerant leaks or low levels of refrigerant

Improper levels of refrigerant can cause drops in  pressure for the evaporator coil, which allows moisture in the air to freeze and accumulate on the HVAC’s evaporator coil.

Outdoor Temperature

Most outdoor HVAC units do not function well in temperatures below 55 degrees F. If temperatures get too low, the HVAC system does not operate properly and that’s when freeze-ups occur.


What To Do When Your Heat Pump or
Air Conditioner Freezes Up

The outside heat pump or AC freeze-ups should be addressed immediately; a continued accumulation of ice can cause permanent damage to any outdoor unit.

Here’s a few steps to take if your HVAC system does freeze up:

  1. Turn it off and let it defrost completely.
  2. Once it has thawed completely, check the airflow.
  3. Replace dirty filters and remove any obstructions

In most cases, this is all that is needed.


If this doesn’t help you may have a more serious refrigeration or airflow problem, and will require a professional NATE technician. Schedule an F.H. Furr certified technician to troubleshoot your HVAC air flow problem and repair refrigerant leaks.


Topics: hvac service