Symptom Related Diagnostic Procedures

TROUBLESHOOTING AIR CONDITIONER

General Testing Requirements

Blower motor runs in all three speeds.
Heater is switched off.
Compressor drive belt is tightened.
Magnetic clutch switches (if not, see below).

The following pressure values must be reached at an engine speed of 2000 rpm, an ambient temperature of approx. 25 °C (77 °F) and with the compressor running.
Low pressure: 0.5 to 1.5 bar.
High pressure: 8 to 14 bar.

Note: The engine hood must be closed after connection of the high and low pressure hoses, since otherwise the values would deviate.

Cooling Has Failed Completely

1. Burst seal on the liquid tank has been bursted.

The system had been overheated. Check the turning direction of the condenser blower. Check the fuse and/or relay, if the condenser blower does not work.

2. Connect the service machine and read the pressure values.

Low pressure: too low.
High pressure: too low.

No refrigerant in the system. Detect the position of leaks. Charge the air conditioner.

3. Switch on the air conditioner and read the pressure values.

Low pressure: too high.
High pressure: too low.

Compressor is faulty.

Low pressure: too low.
High pressure: too high.

Expansion valve is faulty.

Insufficient Cooling

1. Low pressure: normal.
High pressure: too high.

System is overfilled. Discharge and charge the air conditioner.

2. Low pressure: too low.
High pressure: too low.

Insufficient refrigerant in the system. Check for leaks. Charge air conditioner.

3. Low pressure: too high.
High pressure: normal.

Expansion valve is faulty.

Insufficient Cooling After Brief Period of Operation

The cooling effect is okay at first, but gives as operating time progresses.

The evaporator is iced. The icing-up protection switch does not switch off the air conditioner. Check the capillary tube for damage and correct seating.
or
The expansion valve is iced. Heat the expansion valve. The cooling effect of the air conditioner must start up again.

Cause:
Moisture in the refrigerant. Replace the liquid tank. Charge the air conditioner.

Magnetic Clutch Does Not Switch

Part 1:

Part 2: