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A heatpump is used to cool a home in Florida. A relative noticed that the temperature was 90 degrees and that the evaporator (see photo) was sweating. She thinks she heard a piece of ice fall break off inside the evaporator. The unit was installed in 2016.

What causes a heatpump to freeze when used in cooling mode?

  • Poor airflow from a dirty airfilter?
  • Low freon pressure?

The power to the heatpump has been disconnected to ensure that any ice melts.

Is the most likely culprit the AC filter? Any diagnostic instructions are appreciated.

enter image description here

gatorback
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2 Answers2

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There are many possible causes but some of the more common ones are:

  1. Clogged drain
  2. Dirty filter
  3. Excess humidity in the house
  4. Blocked air return or outlet duct

Get it thawed out and make sure that the drain is flowing properly. Check the filter, check the blower for any obstructions.

jwh20
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2

Low refrigerant can also cause this, although that typically happens closer to the condenser. When the refrigerant is low, the condensed refrigerant is allowed to expand earlier, which can lead to excess condensate and/or freezing.

It's unlikely this is the case here, but heat pumps can vary in how far they are from the condenser, so it's not impossible either.

Machavity
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