Air Conditioner - Ice On Indoor Coil

Ice on the indoor coils of an air conditioner can cause the unit to stop cooling well, or may even spit water or ice out of the front of the unit. The primary causes for ice on the coils is the outdoor temperature, fan speed, or a dirty filter.


Temperature / Fan Issues

  • A cool evening in which the outdoor temperature is below 70 degrees F is one of the causes for a window air conditioner to have ice on the indoor coils. The best way to prevent ice on coils is to not run the unit if the outdoor temperature is below 70 degrees F. If the temperature is close to 70 or you are unsure of the temperature, you can turn the thermostat to a warmer setting, set the fan switch to the highest position. This allows for better airflow across the coils.

  • Switching the Fan speed to a lower setting for quieter operation but leaving the thermostat at a higher setting will result in not enough air flowing over the cooling coils. This lower airflow will not keep the moisture off the coils and in turn that moisture will freeze. 


Dirty / Clogged Air Filter


Defrosting Ice on the Coils

  • On models that have just an On/Off setting turn the switch to OFF. The quickest way to defrost the coils is turn the unit off and allow the room air temperature melt the ice. To help speed up the process you can turn the Fan speed to Low; however, this can cause the dripping water to be blown back into the room. After the coils have defrosted, set the temperature control to the middle or warmer setting and set the fan speed at HI-Cool.