Air con intermittent

[cunny678]

I seem to have had this problem on and off since new! Sometimes when I press the air con switch it comes on and sometimes it doesn't. Sometimes it comes on after say five minutes and sometimes it just doesn't come on.

It usually comes on if I stop the car and turn the ignition off and on and occasionally when I just turn the switch on and off. I had the pressure switch replaced about two years ago which seemed to solve problem, but it's back again!

Any ideas? I can't imagine it would be the pressure switch. VW want £95 to look at it and if the switch is faulty they will replace it.


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[RichardSEL]

There's two systems: Climatronic (with two small windows for temps) or pictorial zone display on RNS510. And Climatic three knobs.
Which do you have?
What car?
Year, Miles?

What do you mean "it comes on and sometimes it doesn't."? Blower, coldness, when you're at rest or when your moving? Do both your fans come on when you switch aircon on?

[cunny678]

It's the climatic. The fan and vent work fine it's just the airs not cooled!
It's a passat 2009 2.0 tdi 140 with about 70k on the clock. Just noticed today, that if I leave it on all the time and don't turn off when I stop the car it seems to work.


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[Quatrelle]

Mine's never turned off, summer or winter (demists quicker with the aircon on in winter). It's reckoned it's best to leave it on anyway, saves the seals drying out.

[RichardSEL]

System appears working then. I havn't re-gassed my Climatronic since compressor seized up in '08 and had it changed under warranty. This is the first summer the cooling appears weaker

Refrigerant is type R134a following european environmental laws. The full charge level is 600 grams by weight. An aerosol of R134a with pressure gauge is available from Halfords. They describe the gauge not the weight method to fill: Halfords | EZ Chill Auto Air Conditioning Recharge
A filling video and photos of the filler location are at:
Charge Port Locator - Interdynamics Europe
Halfords own video is at:
Halfords | EZ Chill Auto Air Conditioning Recharge

Kwik Fit auto centres will re-gas for you. If there’s no change in your system’s operation, they won’t charge. £49 as of May, 2014. MoT Testing &amp Servicing

[cunny678]

Seems to work if I leave it switched on all the time! I wonder if it's a faulty switch?


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[RichardSEL]

If you get cold effectively only when you've got forward motion say >30mph, or have had forward motion; and you get nothing when standing still from startup (after about five mins or so) then it's your G65 switch

If you get no cooling even though you've got forward motion then it'll be your RCV valve on your compressor.

There's no diagnostics on the Climatic system itself. Climatic can only be read in the HVAC section of a VCDS scan. But from what you describe I'd try the re-charge first to see whether that brings up your coldness. Then the G65 switch -- you won't loose refrigerant coz it sits on a Schraeder valve. Then lastly the RCV where you will have to evacuate your refrigerant to change out.

I've got those three detailed in my Climatronic .doc, but you won't have the diagnostics part of it. PM me an e-mail address and I can attach it by reply

[cunny678]

Started playing up again even when switched on!! Any ideas?


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[cunny678]

Seems weird now. Sometimes when I turn the air con on the air doesn't cool, but when I turn it off after a few minutes the air gets cooler, not cold but defiantly cooler!

Just wondering if it could be a temp sensor fault?

[RichardSEL]

What have you done so far?

Could be a sensor. Find someone with VCDS and do a basic settings from the help .doc.
Do an Autoscan too and post here? That could show up more listed under HVAC
VWAF User Location Map - VCDS - Google Maps