| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Main switch open. | 1. Close switch. |
| 2. Fuse blown. | 2. Check electrical circuits and motor winding for shorts or grounds. Investigate for possible overloading. Replace fuse after fault is corrected. |
| 3. Thermal overloads tripped. | 3. Overload are automatically reset. Check unit closely when unit comes back on line. |
| 4. Defective contactor or coil. | 4. Repair or replace. |
| 5. System shut down by safety switch | 5. Determine type and cause of shutdown and correct it before resetting safety switch. |
| 6. No cooling required. | 6. None. Wait until calls for cooling. |
| 7. Liquid line solenoid will not open | 7. Repair or replace coil. |
| 8. Motor electrical trouble. | 8. Check motor for open windings, short circuit or burn out. |
| 9. Loose wiring. | 9.Check all wire junctions. Tighten all terminal screws. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Flooding of refrigerant into crankcase. | 1. Check setting of expansion valves. |
| 2. Improper piping support on suction or liquid line. | 2. Relocate, add or remove hangers. |
| 3. Worm compressor. | 3. Replace. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Non-condensable in system. | 1. Remove the non-condensable. |
| 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. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Faulty condenser temperature regulation.. | 1. Check condenser control operation. |
| 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. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Excessive load. | 1. Reduce load or add additional equipment. |
| 2. Expansion valve overfeeding. | 2. Check remote bulb. Regulate superheat. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 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. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Clogged suction oil strainer. | 1. Clean. |
| 2. Excessive liquid in crankcase. | 2. Check crankcase heater. Reset expansion valve for higher superheat. Check liquid line solenoid valve operation. |
| 3. Low oil pressure safety switch defective. | 3. Replace. |
| 4. Worm oil pump. | 4. Replace compressor. |
| 5. Oil pump reversing gear stuck in wrong position. | 5. Reverse direction of compressor rotation. |
| 6. Worn bearings. | 6. Replace compressor.. |
| 7. Low oil level. | 7. Add oil and/or through defrost. |
| 8. Loose fitting on oil lines. | 8. Check and tighten system. |
| 9. Pump housing gasket leaks. | 9. Replace gasket. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 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. |
| Possible Causes | Possible Corrective Steps |
|---|---|
| 1. Operating beyond design conditions. | 1. Add facilities so that conditions are within allowable limits. |
| 2. Discharge valve partially shut. | 2. Open valve. |
| 3. Blown valve plate gasket. | 3. Replace gasket. |
| 4. Dirty condenser coil. | 4. Clean coil. |
| 5. Overcharged system. | 5. reduce charge. |
