Long time no post and surprised to see the change to Big Car Club!

I have 2 x Galaxy Mk 2 2005/6 with aircon issues.   One has error code "intermittent short to ground" and fully gassed aircon wil not pull in clutch.   I have a spare switch from another scrap car, but doesn't look if I can get it off without damaging pipework, so need to bypass the switch for now.

Wiring diagram i have shows a changoever switch with only 2 pins used, but loom on car has 3 wires to sensor (black, brown, yellow/red)

Part is a PT4-H1001-1
1J0 959 126 DRH

But can't find data here or anywhere online!!!

Not yet looked at plug etc on faulty car as need to get wheel arch off to check it and possible front bumper, but does anyone know the connections and function of the switch - is it passive or a pulse sensor for example

rgds
Somerset
UK

Hey John, welcome back! 

That three pin sensor is the pressure sensor, it detects both low pressure and high pressure conditions in the system (Hence the three pins) - one ground and two outputs.

Typical VW wiring would have the ground in the centre and the two outputs either side but that's just a guess, I suspect you'll also find it's a simple on/off switch depending on if the condition is met.