1. Fault symptom: the exhaust temperature of the unit is high (over 100℃).

Possible reasons: the coolant level of the unit is too low (it should be visible from the oil scope, but not more than half); Oil cooler is dirty; Oil filter core is blocked; Temperature control valve failure (bad components); The solenoid valve for oil cut-off is not energized or the coil is damaged; The diaphragm of the solenoid valve for oil cut-off is broken or aged; Fan motor failure; The cooling fan is damaged; The exhaust duct is not smooth or the exhaust resistance (back pressure) is large; The ambient temperature exceeds the specified range (38℃ or 46℃); Temperature sensor failure (control unit); Whether the pressure gauge is faulty (relay control unit).

2. Failure phenomenon: the oil consumption of the unit is high or the oil content of compressed air is high.

Possible reasons: too much coolant, the correct position should be observed when the unit is loaded, and the oil level should not be higher than half; The oil return pipe is blocked; The installation of the oil return pipe (the distance from the bottom of the oil separation core) does not meet the requirements; Exhaust pressure is too low when the unit is running; Oil separation core is broken; The internal partition of the separation cylinder is damaged; The unit has oil leakage; Deterioration or overdue use of coolant.

3. Failure phenomenon: low unit pressure.

Possible reasons: the actual gas consumption is greater than the output gas of the unit; Bleed valve failure (unable to close when loading); Air inlet valve failure; Hydraulic cylinder failure; The load solenoid valve (1SV) is faulty and the small pressure valve is stuck; There is a leak in the user pipe network; The pressure setting is too low; Pressure sensor failure (control unit); Pressure gauge failure (relay control unit); Pressure switch failure (relay control unit); The pressure sensor or pressure gauge input hose leaks;

4. Failure phenomenon: the exhaust pressure of the unit is too high.

Possible causes: air inlet valve failure; Hydraulic cylinder failure; Load solenoid valve (1SV) is faulty; The pressure setting is too high; Pressure sensor failure (Intellisys control unit); Pressure gauge failure (relay control unit); Pressure switch failure (relay control unit).

 5. Fault phenomenon: the current of the unit is large.

Possible reasons: the voltage is too low; Loose wiring; Unit pressure exceeds rated pressure; Oil separation core is blocked; Contactor failure; Main engine failure; Main motor failure;

6. Failure phenomenon: the unit cannot be started.

Possible reasons: the fuse is broken; The temperature switch is broken; Loose wiring; Main motor thermal relay action; Fan motor thermal relay action; Transformer is broken; No power input (control unit); Failure not eliminated (control unit); Controller failure.

7. Fault phenomenon: large current or tripping when the unit is started.Possible reasons: user air switch problem; Input voltage is too low; The interval between star and triangle conversion is too short (it should be 10 ~ 12 seconds); Hydraulic cylinder failure (not reset); Intake valve failure (too wide opening or stuck); Loose wiring; Main engine failure; Main motor failure; 1 TR time relay is broken (relay control unit).

8. Failure phenomenon: the fan motor is overloaded and the fan is deformed.Fan motor failure; Fan motor thermal relay failure (aging); Loose wiring; The cooler is blocked; The exhaust resistance is large.

9. Fault symptom: The dryer is not running.Possible reasons: compressor line disconnected, fuse blown, thermal relay action, high-voltage switch action, compressor blocked, line virtual connection or looseness.

10. Failure phenomenon: The dryer stops within a short time after starting.Possible causes: excessive ambient temperature, blocked condenser, compressor overload, lack of refrigerant, low pressure, excessive intake air, and jammed compressor.

11. Fault symptom: The compressor does not start.Possible causes: incorrect wiring, low voltage, damaged starting capacitor, relay or contactor not closed, open circuit of starting winding, lack of phase.

12. Fault phenomenon: The compressor starts and stops repeatedly due to overload protection.Possible causes: low voltage or three-phase imbalance. Other electrical equipment is connected to the overload protector. The overload protector fails. The operating capacitor is too small. The exhaust pressure is too high. The windings are short-circuited and the thermal relay contacts are stuck.

13. Fault phenomenon: the relay is burnt out.Possible causes: too high or too low voltage, incorrect capacitor operation, repeated start and stop (refer to 2 and 3), inconsistent relay specifications and incorrect mounting seat.

14. Fault phenomenon: the capacitor is burnt out.Possible reasons: mismatch of specifications and high voltage.

15. Fault symptom: the exhaust pressure is too high.Possible reasons: too much refrigerant, air in the refrigeration system, dirty condenser, too high ambient temperature, fault of fan pressure switch, fault of fan motor, incorrect direction of fan rotation, fault of cooling water flow regulating valve.

16. Fault symptom: Exhaust pressure is too low.Possible causes: too little refrigerant dosage, fan pressure switch failure.

This article is transferred from Refrigeration Network.