Heatcraft Mohave, Installation & Operation Manual, Page: 59 / 76

59
Troubleshooting
SYMPTOMS POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS
Fan(s) will not operate 1. Main switch open 1. Close switch
2. Blown fuses 2. Replace fuses. Check for short
circuits or overload conditions
3. Defective motor 3. Replace motor
4. Defective timer or defrost thermostat 4. Replace defective component
5. Unit in defrost cycle 5. Wait for completion of cycle
Room temperature too high 1. Room thermostat set too high 1. Adjust thermostat
2. Superheat too high 2. Adjust thermal expansion valve
3. System low on refrigerant 3. Add refrigerant
4. Coil iced-up 4. Manually defrost coil. Check defrost
controls for malfunction
5. Unit cooler located too close to doors 5. Relocate unit cooler or add strip curtain
to door opening
6. Heavy air infiltration 6. Seal unwanted openings in room
Ice accumulating on ceiling 1. Defrost duration is too long 1. Adjust defrost termination settings
around evaporator and/or on 2. Defective defrost thermostat or timer 2. Replace defective component
fan guards venturi or blades 3. Too many defrosts 3. Reduce number of defrosts
Coil not clearing of frost during 1. Coil temperature not getting above 1. Check heater operation
defrost cycle freezing point during defrost
2. Not enough defrost cycles per day 2. Adjust controller for more defrost cycles
3. Defrost cycle too short 3. Adjust defrost settings for longer cycle
4. Defective timer or defrost thermostat 4. Replace defective component
Ice accumulating in drain pan 1. Defective heater 1. Replace heater
2. Unit not pitched properly 2. Check and adjust if necessary
3. Drain line plugged 3. Clean drain line
4. Defective drain line heater 4. Replace heater
5. Defective timer or thermostat 5. Replace defective component
Uneven coil frosting 1. Located too close to door or opening 1. Relocate evaporator
2. Defrost termination set too low 2. Adjust defrost termination setting
higher.
3. Incorrect or missing distributor nozzle 3. Add or replace nozzle with appropriately
sized orifice for conditions.
General Evaporator Troubleshooting Chart