Noisy A/C belt
 

Hi! The A/C belt on my wife's 3.0D screeches when starting up from cold. You can see that the A/C pulley is not turning when you turn the A/C on. It goes away when you rev the engine and the pulley starts to turn and once the car is warm it doesn't come back. My local mechanic (who is not a BMW specialist....the nearest is 250 km away) suggested initially changing the belt.

What I'd like to know is:

1. is there only one belt (mine says it's a 4PKO810319K4). If there is more than one I assume it'd be better to change them all? Is there a better brand of belt to get? I have read on previous posts that the OEM ones are better than Continental?

2. Is there anything else I should replace while he's replacing it/them. It has done 153K kms.

Cheers

Maybe it your ac compressor that is the problem. It doesn't turn so the belt screeches, but once the ac compressor turns, the belt stop screeching.

Haven't ruled that out yet!!!!

Should be 2 belts, one to drive the a/c, the other to drive the alternator & water pump etc.

Generally the AC comp. will have a clutch on it; so it just free wheels while not in use....my money would be on the belt tensioner being toast and not keeping the belt tight enough.

For reference:
RealOEM.com * Diagram Selection

Hope this helps.