Mark 5 2.0 TDI (2008) Air con issue

[gmhendo]

hi folks
I would appreciate some insight into an air con issue I have. I noticed it was slow to go cool - like 5 - 10 minutes after which it was OK but not icy.
My service guy says the compressor is only making 11-12 bar and is probably worn out. Car had done 140K kms, not a lot I would have thought.

Dies this sound right? And I am told just $1200 will set it right again.

Any comments will be very welcome
Cheers
Geoff

[vdubmotorworx]

Yep. Ac compressors on vw are not great. Mk5 and 6 had issues. Fitted loads and the always fail your way...takes a while to get cold..when cold not 100% ac cold but is working about 60%. New compressor mate..VDUB...

[Mattlock]

Yep. Agreed. I had the exact same issue 12 months ago. Car had about 105k km on the clock. Cost me $1200 to get the compressor replaced. Even with it replaced it's nowhere near as instant as my Mazda CX-7 was but at least it works and the car is cooling within 5 minutes.

[DWBN]

Exact same problem here mate. I recently recplaced the TX valve which is said to fail, but this didn't fix the problem. I was quoted $850 for a brand new OEM compressor from VW and $600 for an aftermarket.

I ended up picking up a new aftermarket compressor from the states, and will be getting the compressor fitted, the system flushed and re-gassed next week.

[gmhendo]

Thanks very much for that guys, at least I know where I am at now.

Dubber I would greatly appreciate knowing where you got you new compressor from...

Thanks again guys

[insanekiwi]

Dwbn, could you point us to where you got the compressor from? Thanks.

[DWBN]

No worries - It's an aftermarket model, but comes with 2yr warranty so should be all good. Will have it fitted on Friday and will post the results.

[brad]

I may as well piggy-back off this thread...

I have a 2007 Octavia. I assume the AC setup is near identical to a MK5/Mk6 Golf. I'm trying to work out if there's a problem brewing that can be fixed before catastrophic failure / large bills.

I rarely use the AC - maybe once a month for 10-20 minutes and it seems to work fine.

What I have noticed is that AC off i use 0.8L/hour fuel when idling. With the AC on the fuel usage is anywhere between 1.6L/hr up to 2.4L/hour. Similarly, I use about 20%-30% more fuel when driving with AC on. It's only something I've noticed in the last 12 months but maybe it's always been like that?

I expect an increase in consumption but this seems excessive. Is this early signs of a probelm with the compressor? (eg: excessive drag).

[Idle]

The rule of thumb used to be that the AC drag approximately equalled one passenger — probably still is.

The VW units I've had show as using about .2 L/hr more at idle, probably due to the increased idle speed when the AC is on.

I'd certainly be investigating before something expensive goes wrong (if it hasn't already...)

[brad]

0.2-0.5L/hr increase is what I'd expect.

Idle speed jumps about 150rpm with AC on.

It's still icy cold so but I think early intervention would reduce costs. Assuming compressor is dieing and need change-out then I guess the receiver / drier / filter thingy is due & maybe the TX valve?

[DWBN]

You don't need to touch anything apart from the compressor if it hasn't already failed. Replacing the condesor and reciever dryer will only be required if the compressor has failed and sent swarf through the system (most common in the denso units).

[Idle]

If the compressor was dying I think it'd have blown before now — that it's working so well suggests it's OK.

I'd check the electronics first — something's causing that excessive load and it shouldn't be anything mechanical.

Could be a valve not opening, perhaps (note I'm not a refrigeration expert.)

[harlie]

hi folks
I would appreciate some insight into an air con issue I have. I noticed it was slow to go cool - like 5 - 10 minutes after which it was OK but not icy.
My service guy says the compressor is only making 11-12 bar and is probably worn out. Car had done 140K kms, not a lot I would have thought.

Dies this sound right? And I am told just $1200 will set it right again.

Any comments will be very welcome
Cheers
Geoff

If it is slow to get cold as opposed to not getting cold at all I have some good news. (this may apply if yours doesn't work at all but it is harder to confirm). You have a Clutch-less Variable Displacement Compressor (VDC) - check that when you turn the AC on and off that there is no clutch engaging/disengaging to confirm.

The VDC is permanently engaged, it has an internal “wash board” that changes angle which in turn alters the length of the piston stroke varying output from 2%(required for lubrication) to 100%. The wash board is moved/actuated by refrig pressure released by the Refrigerant Control Valve (RCV) which is controlled electrically by the AC ECU. The problem is the RCV – it sticks (mine was full of crud)– which is why it works after a while and I’m tipping it drops out after a while too. Good news is this valve can be had for $US32 - 80 depending on where from and is located in the back of the compressor. The system has to be evacuated before the valve is removed and regassed after. It is an easy job.

If you are interested I can post up exactly how to tell if your valve is the problem – you need VCDS and about 5 minutes. It will also help if you identify which compressor you have (I got the phone down in there for a photo of the plate).

If the compressor is not working at all the compressor may have a problem with the wash board which could mean it has fallen apart inside - but I bet the majority of owners replacing compressors only need the valve.

I will add that none of the AC shops I spoke to re this a couple months back had any idea - they just wanted big $ to replace everything.

[harlie]

Yep. Ac compressors on vw are not great. Mk5 and 6 had issues. Fitted loads and the always fail your way...takes a while to get cold..when cold not 100% ac cold but is working about 60%. New compressor mate..VDUB...

Classic signs of a sticky valve! New valve is a lot cheaper and requires a lot less labour than a new compressor, which is probably why industry wants to replace the compressor + drier + TX = profit. Not to mention that nearly all the compressors are factory exchange - which means they have a new $32 valve in them and are resold for how much??

[DWBN]

Same problems and I tried the same thing. New TX valve installed, worked for 15 mins then nothing as it was clogged again. While this does work for some poeple, the source of what is clogging the valve in the first place has not been fixed. AC systems don't just clog up. They are a sealed system that should not lose pressure, or have anything apart from the compressor oil and R134. If the TX vavle is sticking, something has entered the system to do so, and 99.9 it will be the compressor failing sending swarf through the lines.

That said, if you catch it early enough a simpled replacement of the vavle will help, but not fix the issue long term.