MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: daelo on July 08, 2019, 03:30:44 pm

Title: Air con pressure switch - green coolant inside it?!
Post by: daelo on July 08, 2019, 03:30:44 pm
So I have a faulty air con system I believe and think it may be the air con pressure switch after reading around on this forum and others.

Went to have a look to see i could find the switch next to the alternator. When I un-clipped it there seems to be a green liquid inside where the terminals are, thought maybe that is interfering with the connection so gave it a blast of contact cleaner.

It started bubbling, I cleaned it out as best i could with a wipe and flat screwdriver! So anyway images below, surely the switch should be completely sealed, is this indication that the switch is leaking which is throwing the fault and preventing the AC from working?

FYI , was re-gassed a few weeks ago, and it hasn't been checked on VCDS for fault codes.. yet.

Images before i squirted in the cleaner.


(https://i.imgur.com/cMhNydk.jpg)
(https://i.imgur.com/e9cn3tn.jpg)
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: GVK on July 08, 2019, 06:21:44 pm
Thats dye from the AC refrigerant. Switch must be leaking internally.
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: daelo on July 08, 2019, 06:40:12 pm
Thanks GVK, assuming if a "high pressure" switch is leaking then presumably it registers low pressure and most likely isn't allowing the compressor to turn on?

In anycase, surely a replacement should be fitted?
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: GVK on July 08, 2019, 07:45:48 pm
Yep, switch needs replacing if it's leaking.
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: daelo on July 15, 2019, 04:39:18 pm
Small update for anyone following. Replaced the switch with the help of a crowsfoot spanner 17mm .

Still hasnt resolved the issue, however i'm thinking if the sensor threw a fault, would it need clearing with VCDS before it became functional?
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: muff1991 on July 17, 2019, 11:52:08 am
thanks for the update, yes, its worth clearing the code as it could be interfering. don't hold your hopes too much though. some things the codes needs to be cleared, others not so much and just clear themselves anyway.
defo get it scanned with VCDS though as you may have another fault which could be the issue.
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: Shoduchi on July 17, 2019, 12:07:58 pm
You'd always need to replace that pressure sensor, since it was leaking, but now you can have a faulty AC compressor because your gas leaked.
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: pudding on July 27, 2019, 12:59:43 pm
That pressure switch has been redesigned a few times and has always been a troublesome part on VAG AC systems.  Get the latest version from the dealer and all should be well.

You will need to do other checks, such as condenser leaks, HVAC heat exchanger leaks, worn/corroded pump, faulty pump clutch solenoid etc etc.

Sadly AC fixes are rarely simple, or cheap.   We're starting to actually need it in this country now, which will no doubt push repair and parts prices up.
Title: Re: Air con pressure switch - green coolant inside it?!
Post by: J66hhr on July 28, 2019, 02:43:59 am
Look for more green dye.. i had to replace my switch and condensor UV light would come handy if youve got one

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