Hi,

I've got a 300D 2.5 Turbo. My air conditioning works fine, but this year as the weather got warmer and I started using the A/C I noticed I could hear the compressor when it kicked in quite clearly when I was at a red light (idle - inside the car). I can't really hear it when driving. I can't hear it when its turned off (so its not the clutch).

Strange thing is I don't remember it being this loud.

If it is the compressor, what should I do preventatively to avoid complete failure and replacement?

The unit is about 10 years old, with about 140K on it.

I've read elsewhere in the forum to check the belt tensioner (make sure its tight). I can't really check the oil in it - and I don't want to put too much in there.

Anything else I can do diagnostically?

How much noise is normal for a normal compressor (I think its an A/C Delco) in this car?

Thanks guys,
mike