Author Topic: Air con pressure switch - green coolant inside it?!  (Read 1803 times)

Offline daelo

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Air con pressure switch - green coolant inside it?!
« 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.





Offline GVK

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Re: Air con pressure switch - green coolant inside it?!
« Reply #1 on: July 08, 2019, 06:21:44 PM »
Thats dye from the AC refrigerant. Switch must be leaking internally.
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Offline daelo

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Re: Air con pressure switch - green coolant inside it?!
« Reply #2 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?

Offline GVK

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Re: Air con pressure switch - green coolant inside it?!
« Reply #3 on: July 08, 2019, 07:45:48 PM »
Yep, switch needs replacing if it's leaking.
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Offline daelo

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Re: Air con pressure switch - green coolant inside it?!
« Reply #4 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?

Offline muff1991

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Re: Air con pressure switch - green coolant inside it?!
« Reply #5 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.

Offline Shoduchi

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Re: Air con pressure switch - green coolant inside it?!
« Reply #6 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.

Offline Pudding

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Re: Air con pressure switch - green coolant inside it?!
« Reply #7 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.
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Offline J66hhr

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Re: Air con pressure switch - green coolant inside it?!
« Reply #8 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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