K90-KPCS-IM-2
18/04/22
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The following System Troubleshooting Guide lists the most common types of malfunctions encountered with refrigeration systems.
These simple troubleshooting techniques can save time and money minimizing unnecessary downtime and end-user dissatisfaction.
Contact the factory or your local sales representative for further information or assistance.
SYSTEM TROUBLESHOOTING
System Troubleshooting Guide
Condensing Unit Problem
Possible Causes
Compressor will not run. Does not try to start.
1. Main power switch open.
2. Fuse blown or tripped circuit breaker.
3. Thermal overloads tripped.
4. Defective contactor or coil.
5. System shut down by safety devices.
6. Open thermostat or control. No cooling required.
7. Liquid line solenoid will not open.
8. Loose wiring.
Compressor hums, but will not start.
1. Improperly wired.
2. Low line voltage.
3. Loose wiring.
4. Defective start or run capacitor.
5. Defective start relay.
6. Motor windings damaged.
7. Internal compressor mechanical damage.
Compressor starts, but trips on overload protector.
1. Improperly wired.
2. Low line voltage.
3. Loose wiring.
4. Defective start or run capacitor.
5. Defective start relay.
6. Excessive suction or discharge pressure.
7. Tight bearings or mechanical damage in compressor.
8. Defective overload protector.
9. Motor windings damaged.
10. Overcharged system.
11. Shortage of refrigerant.
12. Suction or discharge pressure too high.
13. Inadequate ventilation.
14. Operating system beyond design conditions.
Compressor short cycles.
1. Low pressure control differential set too low.
2. Shortage of refrigerant.
3. Low airflow at evaporator(s).
4. Discharge pressure too high.
5. Compressor internal discharge valves leaking.
6. Incorrect unit selection (oversized).
Contact welded stuck
1. Short cycling.
Compressor noisy or vibrating.
1. Flood back of refrigerant.
2. Improper piping support on the suction or discharge lines.
3. Broken or worn internal compressor parts.
4. Incorrect oil level.
5. Scroll compressor rotating in reverse (three phase).
6. Improper mounting on unit base.
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