A/C compressor pulley/plate and bolt

[clivethegadget]

My A4 (B6) 1.9 TDI 130bhp air-con has stopped cooling recently.
The system was regassed, but I was told I would need a new compressor as the pulley was going around, but not turning the compressor.
I've read elsewhere in the forum that the front fixing bolt and the cover can fall off ... and this could cause this problem.
I looked in the bottom plastic tray, but did not find any parts there.
However, I did remove the plastic air cowling and put my had down and felt the front face of the pulley.
I can feel a hole in the centre where a bolt should be .... so the bolt seems to be missing !
I can also spin a plate around (which seems to have a slot in it).
Now, I can go find a replacement bolt (if I have any idea of size) and loctite it in ... but is there anything else missing ?
The plate that spins ... does this sound like the plate that sometimes goes missing ? have I been lucky and this plate has stayed on ... or is there another plate which should go on top of this before the bolt is inserted ?
Any help (including any ideas on what size bolt !) greatly appreciated !
Thanks

[tony-1977]

I've the exact same problem here! No cooling, and recent re-gas made no difference I've no idea where to locate this pulley where the bolt goes? Could anyone help me? Thanks... :-)

[clivethegadget]

The compressor is located low down behind the bottom left hand side of the radiator when standing at the front of the car peering in.
It is driven by an auxilliary belt. .... looks a bit like another alternator at first glance !
The ribbed belt goes around a grooved pulley wheel attached to the front of the compressor.
If you remove the plastic air intake at the top LHS of the engine bay (the flat ducting which is in two parts), you can just about squeeze your arm down beside the large tubing and touch the front edge of the pulley (if you arm is slim enough!).
On my A4 the front edge of this pulley has a disk which seems to spin by hand without moving the pulley wheel itself. From what others say, this seems to operate like a clutch and drive the shaft whe engaged.
I'm not sure what triggers it to engage though !
My plate feels like it has a hole at the centre (There is no way I can get any sort of angle to be able to actually view this plate).
From what others have said, I would have thought that there should be a bolt in this centre hole.
I have tried inserting some bolts with my fingertips at full stretch ... but no joy. I have tried an M6 20mm bolt and even some very thin bolts ... but nothing seems to go into the hole. I am now wondering if a) there is actually no hole there .. and no bolt every belonged there ... or (b) the bolt has sheared off completely (in which case I'm stuffed !)
I would be interested to know what you feel (or see) at the centre of this pulley.
If you have a slipping bolt then others have fixed this problem with a little bit of loctite and tightened it up with a spanner (if its not already fallen off along with the plate into the plastic sub-tray beneath the car.
Let me know what you find !

[tony-1977]

Thanks, I'll take a look!!

Does anyone know which fuse(s) / relay(s) are used in the Climate Control system?

Thanks :-)

[tony-1977]

OK guys.... I've found the compressor. The disk-like plate on the front does rotate freely. It has a 10mm bolt attached to the middle (I think it's a bolt??) I've checked over this thouroughly and it does NOT spin when I have the air con on, even though the pulley is turning.. The two fuses for the air con (1 and 6) are fine. Is there a relay I can check? BTW, I can't find where the wiring goes to the compressor? I want to check the connections here when I can find them. Can anyone point me in the right direction of this?

Thank you ... :-)

[tony-1977]

Anyone? :-)

[clivethegadget]

I'm afraid I don't know too much about the air con myself.
This pdf might help you ... there is some diagram of the aircon circuitry.
http://www.volkspage.net/technik/ssp/ssp/SSP_254.pdf
I am a bit confused as the Haynes Page 3.11 manual says "As no clutch is fitted to the air conditioning compressor (the compressor operates continuously), do not operate the engine if it is known to be short of refridgerant, as this will damage the compressor."
No clutch ??? Really ? The comments in this forum suggest otherwise, and the spinning plate which does not turn with the pulley seems to suggest that there is a clutch.
Surely, the fact that there is wiring to the compressor must be because there is a clutch, otherwise it would only need to be directly turned by the belt and pulley.
I think the aircon control unit sends a variable signal on wiring to the compressor clutch .. but I don't know if anyone can confirm this is so.
In my case, the central bolt which should fix the clutch plate to the pulley is either missing or sheared off ... I can't really be sure as I cannot get a position to see. But I cannot get anything to fit by touch into the hole where the bolt should be .. even with a very slim bolt to try to check the hole's depth. Perhaps the Audi garage sheared it off when they tried to tighten it ... I'll never know.
I am unsure if it is worth pursuing work to improve access to the compressor and perhaps drilling out/removing any sheared bolt.
Then perhaps I can insert a new bolt and locktite/screw it in.
Is it more likely that the clutch mechanism is knackered and would it be worth trying to buy an old compressor to swap clutch parts ?
Otherwise I will have to go for a full new, expensive compressor.

[RickT]

Hi,

This happened to my dad's, the plate fell off bolt and landed on the under tray,

We put the end plate back on, locktight on the bolt and fasterned back on and its been fine since. (touch wood)

Rick

[tony-1977]

Hi,

This happened to my dad's, the plate fell off bolt and landed on the under tray,

We put the end plate back on, locktight on the bolt and fasterned back on and its been fine since. (touch wood)

Rick

I wish mine was this simple!! I'm tearing my hair out!!

[leeoz]

Clive, Tony - have you plugged the car into a VAG-COM - I have recently had loads of air-con issues and in the end it was the G65 Pressure sensor, because that had failed the system would not pull the compressor in (engage the clutch) and there was no cooling, just loads of toastie hot air.

If you can get it plugged in it might save a lot of grief, the sensor cost £49 and 5 mins