Pressures, Checking For Vehicles With Expansion Valve and Receiver (With Internally Regulated Compressor)

Pressures, Checking For Vehicles With Expansion Valve And Receiver (with Internally Regulated Compressor)

NOTE:
- Connecting service station
- Observe test conditions. Component Tests and General Diagnostics

- Set engine speed to 2000 rpm.
- Observe pressure gauge of service station.

NOTE:
- Switching pressures and design of refrigerant circuit switches are vehicle-specific.
- Pressures must be measured at service connections; component locations of these connections are vehicle-specific Heating, air conditioning or Air conditioning.

Specifications

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 fault can be found and air conditioner operation is not OK when test is repeated, flush refrigerant circuit with compressed air and nitrogen.







NOTE: If operation is not OK after refrigerant circuit has been flushed, expansion valve must be replaced.







NOTE:
- It is not initially necessary to flush the refrigerant circuit with compressed air and nitrogen when this problem occurs. Normally, there is only a small quantity of moisture in the system which can be removed by lengthy evacuation.
- If problem involving moisture in refrigerant circuit only occurs after a lengthy operating period or only infrequently (low pressure drops below specification and evaporator ices up), it is sufficient to replace the dryer (adjust quantity of refrigerant oil). Refrigerant circuit is then to be evacuated for at least 3 hours.







NOTE: If the function of the air conditioning system is not OK when the test is repeated, reinstall old expansion valve and flush refrigerant circuit with compressed air and nitrogen. Then replace compressor and receiver.







NOTE:
- If the function of the air conditioning system is not OK when the test is repeated, reinstall old expansion valve and flush refrigerant circuit with compressed air and nitrogen. Then replace compressor and receiver.
- With this fault, evaporator may ice up although quantity of refrigerant in circuit is OK.







NOTE:
- Overfilling with refrigerant oil can occur if, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil.
- If there is too much refrigerant oil in the circuit, drain compressor and replace receiver. After flushing refrigerant circuit, add correct amount of refrigerant oil to circuit.