Operation CHARM: Car repair manuals for everyone.

Refrigerant Pressure Sensor / Switch: Service and Repair







Air conditioner
Empty (recycling).

Plug (B12)
Disconnect from refrigerant pressure transmitter (B12), by pressing the retaining spring (arrow).

Refrigerant pressure transmitter (B12)
Unscrew.

Connection in receiver dehydrator
Seal off (parts set 140 830 01 27).

Install
In reverse sequence. Lubricate O-ring with compressor oil (refer to note) and tighten the refrigerant pressure transmitter (B12) to 10 ± 4 Nm.

Air conditioner
Evacuate, refill, check function and check for leaks; run engine at idle speed only in the first 4 minutes.

Function test
Perform by disconnecting plug at coolant temperature sensor B10/8 and setting 310 Ohm (stage I) or 250 Ohm (stage II) with an ohm decade; switch on ignition and set control unit (KLA) to "Auto". Auxiliary fans rotate clockwise.


NOTE: After completing the work:
Erase fault memory in the control unit.





Auxiliary Fan Switching Points

In the 1st stage, the auxiliary fans cannot cut in at outside temperatures < +5 °C, but do cut in at outside temperature > +10 °C.

NOTE: Parts which have come into contact with compressor oil for R12 or R134a may only be installed in systems operating with the same refrigerant.






Special tool