42 Supply Air Temperature Too Low (Check Alarm)

Thermo King Alarm Code

Description	Corrective Action
Supply Air Temperature Too Low (Check Alarm) During Chill or Frozen Mode: Supply air temperature is too low compared to return air temperature under operating conditions. Indicates: Ice or frost on evaporator coil Low heating capacity Incorrect evaporator fan operation Incorrect connection or location of supply or return air sensors	Check for sensor or evaporator fan alarm codes. Open evaporator door. Inspect coil for ice or frost and initiate manual defrost if necessary. Check for correct evaporator fan motor rotation and operation. Check supply and return sensor connections and locations.