View Full Version : Question Aircon Pressure Switch Replacement

14-06-2017, 11:07 PM
I need to replace this pressure switch on the aircon rad of my 2008 s Line.
I bought a genuine one from the dealer together with a new o ring.
When I unscrewed the old pressure switch the old o ring came off with it.
I have changed one of these before on my B6 but am a bit puzzled as to how to fit the o ring
before screwing the new switch onto the threaded part containing the Schrader valve.
It looks to me as if I should slide the o ring over the threads so that it sits at the base of the threads
and when the switch body reaches it, the o ring is compressed by the smooth tube below the female threaded
part of the switch.
Is that the correct approach?

15-06-2017, 07:39 AM
Yes, slide o ring first and sensor(5Nm, does not matter but:)) after!

15-06-2017, 09:47 PM
Thanks Gunnar. That reassured me enough to go for a re-gas which successfully revived the system so I now have a cool car again.
I'm still puzzled as to why the gas was lost in changing the pressure sensor but assume that maybe it can happen in removing the old sensor.

16-06-2017, 04:48 AM
You probably lost gas/pressure already when old sensor was still attached, I had same puzzle...but faulty G395 leaks, valve should close very quick if removing(if not in slow motion:)) old one.

16-06-2017, 09:21 PM
Good point. That is probably what happened.