– Air compressor room temperature is too high.

– The lack of maintenance for the air compressor:
The efficiency of lubricating oil is reduced;
The oil filter element is blocked.

– The cooling system failure:
Dirty oil cooler;
Damaged cooling fan; Fan motor failure;
The exhaust pipe does not work well or the exhaust resistance is large.

– The component is broken:
The temperature control valve is faulty;
The oil-cut solenoid valve is not energized or the coil is damaged;
The diaphragm of the oil cut solenoid valve is cracked or aged;
Temperature sensor failure (control unit);
The pressure gauge is faulty (relay-controlled unit).