Troubleshooting Using Pressure Measurement (R 134a) - Refrigerant System

Troubleshooting By Means of Pressure Measurement







NOTE: Connect service station to car and open both valves on the charging hoses. Adjust air conditioner controls as described for air conditioner performance measurement.
Run vehicle engine at approx. 2000 rpm.







High intake and outlet pressures suggest an overfilled system, a contaminated condenser or a faulty [1][2]auxiliary fan.

Remedy:
Draw out refrigerant, discharge and recharge system, clean condenser and check additional fan, replacing if necessary.







High inlet pressure and normal outlet pressure indicate a defective compressor.

Remedy:
Replace compressor.







Compressor does not run with equal inlet and outlet pressures.

Remedy:
If icing protection facility has deactivated compressor, check evaporator sensor or power supply to clutch. Otherwise check clutch mechanically (by slipping).







Low inlet pressure and normal outlet pressure indicate an insufficient charged volume or restricted low-pressure side of the system.

Remedy:
1. If evaporator has iced up, check evaporator sensor.
2. Draw out and measure refrigerant. If the amount drawn off corresponds approximately to the specified fill amount, check through flow of expansion valve and then evacuate and refill system.







Low inlet pressure and high outlet pressure indicate a restricted high pressure side.

Remedy:
Check condenser, dehumidifier and expansion valve for conductivity.