Refrigerant Pressure Sensor / Switch: Testing and Inspection

A/C Pressure Switch -F129-

Check function:
- Start engine
- Compressor switched on (operating mode "Auto" on A/C control head adjusted).

- Compressor should run:







- Disconnect harness connector -B- from switch
- Compressor off (low pressure switch open).
- Remove switch -A- and connect connector -B-.
- Compressor is not switched on (low pressure switch open).

- Compressor not running:
- Disconnect harness connector -B- from switch -A- and bridge terminals 1 and 2 on connector -B- See Compressor is switched on.


NOTE:
- If the compressor is switched on when bridging the connector, the switch is faulty or there is not enough pressure in the refrigerant system (refrigerant system empty).
- In order to check pressures in A/C system send vehicle to an authorized VW/Audi A/C workshop.
- If the compressor is not switched on and A/C Pressure Switch -F129- is displayed in measuring value block for compressor cut-off condition, locate and eliminate open circuit in wiring connection between A/C Pressure Switch -F129- and A/C Control Head -E87-.
- On vehicles from model year 2002 High Pressure Sensor -G65- is installed instead of A/C Pressure Switch -F129-.