Audi A4 Clutch & AC Compressor - 2002

"About two years ago, or even longer, I had a faulty pulley on the supercharger of my A4 1.9 TDI AVB. I had a used one lying around from a defective supercharger, so I installed it. The supercharger spun easily, and there were no visible metal shavings in the oil, nor any discoloration of the oil. After about a year, the same thing happened again: the clutch was defective. I then installed an aftermarket supercharger (Hella Behr), and now, after another year, the clutch is defective on this one as well."

When I rebuilt the compressor, the original one was easy to turn, and the oil drained from it was clean. I adjusted the oil level in the new compressor to match the old one, plus about 15-20ml more. I also checked the throttle, and there were no shavings inside.

Is it recommended to flush the system, even if you don't see any contamination or debris in the oil? Or what else could be the cause? (Unfortunately, I don't have any flushing equipment.)

Hello,

Are you sure the filling volumes were correct? Perhaps the compressor is simply running too heavily under load?

Best regards, Rainer.

I'm not entirely sure, but the compressor has been working for 10 years, and maybe a climate control service was performed once, where the oil that was extracted was simply refilled.

So you mean that less oil is better?

A friend of mine called me a few days ago and he's having the same problem, and he's also wondering why.

Hi.

"Just chiming in here, I'm experiencing a similar problem with a similar car."

Today, I took our Audi A6 4B (1.9 TDI AVF engine, 2002) to the workshop for an A/C service because it wasn't blowing cold air anymore. However, there were still about 500g of refrigerant in the system, and even when the system was filled to its full capacity of 650g, it still didn't work. The A/C unit didn't report any errors, and the Bosch diagnostic tool in the workshop didn't show any faults related to the A/C system.

I discovered that the pulley rotates freely against the central part of the compressor. The central part has a slight resistance, but it doesn't catch, and it feels okay.

Based on my research so far, the overload coupling either fails when the compressor is truly blocked or running very sluggishly, or, unfortunately, when the plastic or rubber connectors are old. (In my case, the car is 13 years old and has 227,000 kilometers.)

I'd like to replace the pulley now, before I buy a new compressor. How do you remove this part? I've already loosened a small screw in the center (10mm head, probably M6), but nothing has moved yet. What's the procedure for disassembly? I want to remove this part before ordering a new one, so I can directly compare it to see if it's the right one.

Thank you and best regards.

Matze.

If the compressor is the same as mine, loosen the middle M6 screws and pull down the metal drive disc. It might be a bit difficult if it gets stuck on the teeth. Then, remove the retaining ring, and you can then pull off/remove the pulley with the bearing.