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Table 8.
System Troubleshooting Chart
PROBLEM
POSSIBLE CAUSES
Compressor
1. Main switch open.
will not run
2. Fuse blown.
3. Thermal overloads tripped.
4. Defective contactor or coil.
5. System shut down by safety devices.
6. No cooling required.
7. Motor electrical trouble.
8. Loose wiring.
Compressor
1. Flooding of refrigerant into crankcase.
noisy or vibrating
2. Worn compressor.
High
1. Non-condensables in system.
discharge
2. Fan not running.
pressure
3. Dirty condenser coil.
4. System overcharged with refrigerant.
Low discharge
1. Insufficient refrigerant in system.
pressure
2. Low suction pressure.
High suction
1. Excessive load.
pressure
2. Expansion valve overfeeding.
Low
1. Lack of refrigerant.
suction
2. Evaporator dirty or iced.
pressure
3. Expansion valve malfunctioning.
4. Condensing temperature too low.
Compressor
1. Operating beyond design conditions.
thermal protector
2. Dirty condenser coil.
switch open
3. Overcharged system.
Fan(s) will
1. Main switch open.
not operate
2. Blown fuses.
3. Defective motor.
4. Defective defrost control.
5. Unit in defrost cycle.
6. Coil does not get cold enough to reset thermostat
Room
1. Control cut out set too high.
temperature
2. Superheat too high.
too high
3. System low on refrigerant.
4. Coil iced-up.
Ice accumulating
1. Defrost duration is too long.
on ceiling around
2. Fan delay not delaying fans after defrost period.
evaporator and/or
3. Defective defrost control or sensor.
on fan guards'
4. Too many defrosts.
venturi or blades
Coil not clearing
1. Coil temperature not getting above freezing
of frost during
point during defrost.
defrost cycle.
2. Not enough defrost cycles per day.
3. Defrost cycle too short.
4. Defective defrost control or sensor.
Ice accumulating
1. Defective heater.
in drain pan
2. Unit not installed properly (out of level)
3. Drain line plugged.
4. Defective control.
18
Installation and Operations Manual
POSSIBLE CORRECTIVE STEPS
1. Close switch.
2. Check electrical circuits and motor winding for shorts or grounds.
Investigate for possible overloading. Replace fuse after fault is corrected.
3. Overloads are automatically reset. Check unit closely when unit comes
back on line.
4. Repair or replace.
5. Determine type and cause of shutdown and correct it before resetting
safety switch.
6. None. Wait until calls for cooling.
7. Check motor for open windings, short circuit or burn out.
8. Check all wire junctions. Tighten all terminal screws.
1. Check setting of expansion valves.
2. Replace.
1. Remove the non-condensables.
2. Check electrical circuit. Replace if motor fails.
3. Clean.
4. Reclaim refrigerant and recharge proper amount.
1. Check for leaks. Repair and add charge.
2. See corrective steps for low suction pressure.
1. Reduce load or add additional equipment.
2. Check remote bulb. Regulate superheat.
1. Check for leaks. Repair and add charge (see refrigerant charge chart).
2. Clean.
3. Check and reset for proper superheat.
4. Check ambient temperature 50°F to 100°F.
1. Add equipment so that conditions are within allowable limits.
2. Clean coil.
3. Reduce charge (see refrigerant charge).
1. Close switch.
2. Replace fuses. Check for short circuits or overload conditions.
3. Replace motor.
4. Replace defective component.
5. Wait for completion of cycle.
6. Adjust fan delay setting of control.
1. Adjust control.
2. Adjust thermal expansion valve.
3. Add refrigerant. See refrigerant charge chart. See page 2.
4. Manually defrost coil. Check defrost controls for malfunction.
1. Adjust defrost termination temp on control.
2. Adjust fan delay setting or replace bad sensor.
3. Replace defective control or sensor.
4. Adjust number of defrosts.
1. Check heater operation.
2. Adjust control for more defrost cycles.
3. Adjust defrost control, defrost duration setting.
4. Replace defective component. .
1. Replace heater.
2. Check and adjust if necessary.
3. Clean drain line.
4. Replace defective component.
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