Several common problems can cause the ductless (split air) air conditioner to freeze-up:

Insufficient Air Flow


  • Anything that restricts air flow 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, which will diminish the system's cooling capacity.
  • Dirty air filters can seriously impede air flow.

Outdoor Temperature


  • Most air conditioning units do not function well in temperatures below 60 degrees F.
  • If night-time temperatures are too low, the system will not operate properly and freeze-ups can occur.


To minimize freezing of the indoor unit coil during cool mode, units feature Freeze Protection:


  • When the compressor operates continuously for 10 seconds and the temperature of the indoor coil has been below 32°F for 10 seconds, the compressor will stop, and the error will be recorded in the malfunction list.
  • The indoor unit fan will continue to operate. When the temperature of the indoor coil rises to 45°F for more than 3 minutes the compressor will restart and the system will continue functioning.