16
temperature too
high.)
Superheat too high
Adjust expansion valve.
Room thermostat set too high
Adjust thermostat
Coil iced-up
Manually defrost coil. Check defrost
time, period, controls.
Defective distributor
Replace.
Uneven coil
frosting.
Defective distributor
Replace
Defective heater
Replace
Defrost termination set too low
Adjust defrost termination setting higher
and move defrost thermostat.
Ice build up in coil
quickly
Fin spaced too narrow
Replace coil
Evaporating temperature too low
Adjust expansion valve
Decrease of air volume
Check fan and clean air filter
Unit cooler capacity is too small
Replace unit cooler
Fan not operating
Main switch open
Close switch
Blown fuses
Replace fuses. Check for short circuits
or overload conditions
Defective motor
Replace motor
Defective timer or defrost thermostat
Replace defective component
Unit in defrost cycle
Wait for completion of cycle
Coil does not get cold enough to reset
thermostat.
Adjust fan delay setting of thermostat.
Ice accumulating in
drain panel
Defective heater
Replace heater
Drain line plugged
Clean drain line
Defective drain line heater
Replace heater
Defective timer or defrost thermostat
Replace defective component.
Symptoms
Possible causes
Solution
Coil not clearing of
frost during defrost
cycle
Coil temperature not getting above freezing
point during defrost.
Check heater operation
Insufficient defrost period
Adjust timer or more defrost cycle
Defrost cycle too short
Adjust defrost thermostat or timer for
longer cycle
Defective timer or defrost thermostat
Replace defective component
Ice accumulating
on ceiling ,around
Defrost time is too long
Adjust defrost termination thermostat.
Not delaying fans after defrost period.
Check fan delaying thermostat
