E30 Zone

Hi E30'ers!

So i start my car up this morning and hear this humming sort of noise coming from my engine bay. I left the car running and had a look, it seems as if it's the A/C unit (compressor i think). As soon as i put the A/C on, the noise went away, when i switch it off, the noise it back. Could it be the belt or something?

fannyj wrote:Hi E30'ers!

So i start my car up this morning and hear this humming sort of noise coming from my engine bay. I left the car running and had a look, it seems as if it's the A/C unit (compressor i think). As soon as i put the A/C on, the noise went away, when i switch it off, the noise it back. Could it be the belt or something?

Sounds like it's the compressor clutch.

With the A/C off, the outer part of the pulley is free to spin with the belt, but is not locked to the pulley centre, so the pump does not turn. When you turn the A/C on, the electromagnetic clutch locks the inner and outer parts of the pulley together and the pump is then driven.

I think you probably have a dodgy bearing or some dirt in the compressor clutch. With the A/C on, everything is locked together, so the noise goes away.

Ian.

I see... will take a look at it... thanks!