Last summer I replaced the air conditioner clutch magnetic coil as the old one had failed and was electrically "open". A/C ran fine for the rest of summer until whenever we stopped using it. It got hot enough last week here to turn on the A/C and no cold air. I just now electrically tested the clutch and got a resistance reading of "Infinity" indicating that the magnetic coil has burnt out.

Why would this happen so soon? Is it just one of those s*** happens sort of things? The replacement coil was off another compressor. Do these coils just have a finite lifetime and the used one I picked up was also on its last legs?

I was always told to use the AC regularly, but that probably hasnt helped in your case. However its probably worth investing in a new compressor and clutch assembly.

Did you have the gas level checked?

Are the two fans working as they should?

Edited 29 April, 201313 yr by Frisco

Is everything else attached to the aux belt OK? Particularly the alternator pulley.

Sent from my Nexus 4 using Tapatalk 2

Looks like I need to do a bit of replacement. The tensioner/damper is broke, which apparently means a bad alternator pulley, both of which I suppose could lead to damage to the aircon clutch/magnet.

I got all of the replacement parts (tensioner, A/C clutch assembly, alternator pulley) yesterday, so I'll be tackling replacing all of this today, after I hunt around here for the proper procedure to take off the alternator pulley, A/C clutch, etc. as the Haynes manual I have doesn't describe these procedures.

I still wonder why an electromagnet would burn out though.

Removing the alternator clutch requires a special tool.

On my car (110TDI), I did the following (from memory) when I had to replace the pulley on my alternator as it had broken off:

- removed the old belt

- removed the tensioner

- removed the pulley from the PAS pump

- removed the PAS pump

- detached the large rad

- removed wiring from alternator

- removed retaining bolts for alternator

- spent an hour wiggling the alternator to get it out (the bushes seize)

- local garage fitted the new pulley to the alternator

- refitted (so steps above, but in reverse & remembering to use the locking pin on the tensioner).

I replaced my tensioner unit even though it wasn't broken on the grounds that it had a good 180k+ miles on it.

I had a set of pictures too: http://www.matthewames.co.uk/briskoda/index.php?loc=./20110211_alternator

I had a set of pictures too: http://www.matthewam...0211_alternator

Thanks for the link to pictures!

I just realized I need that special tool, so now to try to get a hold of my mechanic friend who might have. Good thing I actually read through the procedure before taking the car apart and getting stuck here...

I finally tackled this today, having gotten the assumed necessary replacement parts last month, but as my wife's car has working A/C we've been mostly driving that.

I'm thinking that the free running pulleys do not come from the factory with gobs of welding on them:

http://andrew.freedomlives.net/piwigo/picture.php?/44/category/6

To try to get the thing off, I cut down the pulley a bit to get a better grip in the vise, as the outer splines on the pulley got blocked by the welding, so I couldn't get the tool to grip there. No luck getting it off-- the inside turned a half turn clockwise, but refused to go counter-clockwise, which is how I think it should be turning to loosen. This is now dodgy part number 3, after the radiator fan with huge motor from an Audi that only ran at one speed, and the timing belt tensioner that was shimmed with washers to make it fit which slacked off and killed some valves last year. And maybe I am forgetting something else as well... Expensive lesson learned is not to buy a used car from a mechanic, who has a stash of VW group parts to fit onto the salvage car he's trying to turn around and sell...

And before I got to too much trouble with the alternator, which makes a clicking when I spin it that I suspect might mean it needs new bearings or some other sort of rebuild, is this even the right model for a 1.9 TDI AGR engine?:

http://andrew.freedomlives.net/piwigo/picture.php?/43/category/6

Thanks,

Andrew

When you replaced the clutch did you shim it to the correct clearance?

I'd be looking at the fan controller for your a/c problem. They can fail so the clutch coil is always on (ignoring the temperature/pressure sensors). You wouldn't notice that the compressor was running in winter and eventually the coil overheated and went open circuit.

I'm not sure what radiator fan you have fitted. If it is a 2-speed fan then you might find the fan controller is at fault. If it is a single speed fan then it may have caused a problem with the controller.

It has the proper two speed fan and auxiliary fan now.

But I will check more carefully these controllers and thermostats, as it is entirely possible that there is a fault with them-- thanks for that suggestion!

Do the fans come on (at low speed) when the a/c is turned on?