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6/21 57-02611 ©2021, Refrigerated Solutions Group™. All rights reserved. 25
System Troubleshooting Chart
1. Main switch open. 1. Close switch.
2. Fuse blown. 2. Check electrical circuits and motor winding for shorts or grounds.
3. Thermal overloads tripped. Investigate for possible overloading. Replace fuse after fault is corrected.
4. Defective contactor or coil. 3. Overloads are automatically reset. Check unit closely when unit
5. System shut down by safety devices. comes back on line.
6. No cooling required. 4. Repair or replace.
7. Liquid line solenoid will not open. 5. Determine type and cause of shutdown and correct it before
8. Motor electrical trouble. resetting safety switch.
9. Loose wiring. 6. None. Wait until calls for cooling.
10. Phase loss monitor inoperative. 7. Repair or replace coil.
8. Check motor for open windings, short circuit or burn out.
9. Check all wire junctions. Tighten all terminal screws.
Compressor noisy or 1. Flooding of refrigerant into crankcase. 1. Check setting of expansion valves.
vibrating 2. Improper piping support on suction or liquid line. 2. Relocate, add or remove hangers.
3. Worn compressor. 3. Replace.
4. Scroll compressor rotation reversed. 4. Rewire for phase change.
High discharge 1. Non-condensables in system. 1. Remove the non-condensables.
pressure 2. System overcharges with refrigerant. 2. Remove excess.
3. Discharge shutoff valve partially closed. 3. Open valve.
4. Fan not running. 4. Check electrical circuit.
5. Head pressure control setting. 5. Adjust.
6. Dirty condenser coil. 6. Clean.
Low discharge 1. Faulty condenser temperature regulation. 1. Check condenser control operation.
pressure 2. Suction shutoff valve partially closed. 2. Open valve.
3. Insufficient refrigerant in system. 3. Check for leaks. Repair and add charge.
4. Low suction pressure. 4. See corrective steps for low suction pressure.
5. Variable head pressure valve. 5. Check valve setting.
High suction 1. Excessive load. 1. Reduce load or add additional equipment.
pressure 2. Expansion valve overfeeding. 2. Check remote bulb. Regulate superheat.
Low suction pressure 1. Lack of refrigerant. 1. Check for leaks. Repair and add charge.
2. Evaporator dirty or iced. 2. Clean.
3. Clogged liquid line filter drier. 3. Replace cartridge(s).
4. Clogged suction line or compressor suction gas strainers. 4. Clean strainers.
5. Expansion valve malfunctioning. 5. Check and reset for proper superheat.
6. Condensing temperature too low. 6. Check means for regulating condensing temperature.
7. Improper TXV. 7. Check for proper sizing.
Little or no oil 1. Clogged suction oil strainer. 1. Clean.
pressure 2. Excessive liquid in crankcase. 2. Check crankcase heater. Reset expansion valve for higher superheat.
3. Low oil pressure safety switch defective. Check liquid line solenoid valve operation.
4. Worn oil pump. 3. Replace.
5. Oil pump reversing gear stuck in wrong position. 4. Replace.
6. Worn bearings. 5. Reverse direction of compressor rotation.
7. Low oil level. 6. Replace compressor.
8. Loose fitting on oil lines. 7. Add oil and/or through defrost.
9. Pump housing gasket leaks. 8. Check and tighten system.
9. Replace gasket.
Compressor loses oil 1. Lack of refrigerant. 1. Check for leaks and repair. Add refrigerant.
2. Excessive compression ring blow by. 2. Replace compressor.
3. Refrigerant flood back. 3. Maintain proper superheat at compressor.
4. Improper piping or traps. 4. Correct piping.
Compressor thermal 1. Operating beyond design conditions. 1. Add components to bring conditions within acceptable limits (i.e.,
protector switch 2. Discharge valve partially shut. CPR/EPR valves, additional condenser surface, liquid injection, etc.).
open 3. Blown valve plate gasket. 2. Open valve.
4. Dirty condenser coil. 3. Replace gasket.
5. Overcharged system. 4. Clean coil.
5. Reduce charge.
Compressor will
not run
PROBLEM
POSSIBLE CAUSES
POSSIBLE CORRECTIVE STEPS
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