Checking With Expansion Valve and Reservoir (With Internally Regulated A/C Compressor)

Checking With Expansion Valve And Reservoir (with Internally Regulated A/C Compressor)

NOTE:
- Connecting service station.
- Observe test requirements.

- Bring engine speed up to 2000 RPM.
- Observe manometer battery.

NOTE: Switching pressures and design of refrigerant circuit switches are vehicle-specific.

The pressures should be measured at the service connections. The location of these connections is vehicle-specific.

Specified values:

High-pressure side:
Increasing from initial pressure (on connecting pressure gauges) to max. 20 bar

Low-pressure side:







Decreasing from initial pressure (on connecting pressure gauges) to value in graph.

A - High pressure in bar
B - Low pressure in bar
C - Permissible tolerance range







NOTE: If no malfunction can be found and the function of the A/C system is not correct after repeating the test, flush (clean) refrigerant circuit with refrigerant R134a. If that is not possible in this workshop, flush refrigerant circuit with compressed air and remove moisture with nitrogen.







NOTE: If the function is not correct after flushing the refrigerant circuit, the expansion valve must be replaced.







NOTE: Always replace reservoir in case of this malfunction.







NOTE: If the function of the A/C system is not correct when the test is repeated, re-install old expansion valve and flush refrigerant circuit with compressed air and nitrogen. Then replace A/C compressor and reservoir.

NOTE:
- If A/C system function is not OK when the test is repeated, flush (clean) refrigerant circuit. Then replace A/C compressor and reservoir.
- With this malfunction, evaporator may ice up although quantity of refrigerant in circuit is OK.







NOTE:
- Overfilling with refrigerant oil can occur in the event, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil.
- If the A/C compressor is not replaced, the refrigerant oil should be drained from the A/C compressor via the drain plug (replace O-ring). Out of the entire quantity of refrigerant oil, 50 grams should be put in the A/C compressor and the rest in the refrigerant circuit.