AC Compressor Noise

[Sump]

What does it mean when an AC compressor makes a rattling noise when the clutch engages yet the noise goes away when the clutch disengages?

( Compressor clutch not gearbox clutch )

[kambites]

Sounds like a bit of debris in the pump? The pump obviously wont be spinning if the clutch is disengaged so it wouldn't make a noise. Is the air con still working properly?

[powerstroke]

Sump said:

What does it mean when an AC compressor makes a rattling noise when the clutch engages yet the noise goes away when the clutch disengages?

( Compressor clutch not gearbox clutch )

That the compressor is about to fail !! I wouldn't let it run
Pull the plug !!! as if it locks up it wil likely take the belt out and shed metal and crap into the
Pipe work ..

[Scootersp]

Can you reach the aircon pulley with your hand? the inner part on mine you can move by hand independant to the outer ring the belt runs on and if you can do the same you will probably feel the roughness/wear.

[tehguy]

Erm, the compressor only runs when the clutch engages, that's the whole point of the clutch - to switch it on and off!

Can you make a video or sound recording of the rattling and are you sure it's not normal? The whole A/C system is sealed and pressurised so it would be fairly hard for anything to get in to the pipes or compressor itself, and there are pressure switches which will not allow the clutch to engage if the pressure is too low (e.g there's a leak).

There's also an air dryer in the system to remove water vapour from the system.

[squeezebm]

tehguy said:

Erm, the compressor only runs when the clutch engages, that's the whole point of the clutch - to switch it on and off!

Can you make a video or sound recording of the rattling and are you sure it's not normal? The whole A/C system is sealed and pressurised so it would be fairly hard for anything to get in to the pipes or compressor itself, and there are pressure switches which will not allow the clutch to engage if the pressure is too low (e.g there's a leak).

There's also an air dryer in the system to remove water vapour from the system.

What if something had come loose inside the compressor ? Not enough for it to fail....yet. Have you ever had a look inside of a refrigeration compressor? And what is this air dryer in the system? Or do you mean liquid line filter drier?

[HustleRussell]

The compressors are quite simple. You won't get 'bits' inside them which are big enough to be heard rattling about. It's far more likely to be a failing bearing, either that or the compressor is dying because you have the wrong amount of lubricant in the system.

[kambites]

tehguy said:

The whole A/C system is sealed and pressurised so it would be fairly hard for anything to get in to the pipes or compressor itself, and there are pressure switches which will not allow the clutch to engage if the pressure is too low (e.g there's a leak).

It's not hard for a bit of compressor to get into the compressor. That's exactly what happened to our Octavia - something inside the compressor broke which then jammed and the whole thing just disintegrated. It rattled like buggery when the air con tried to turn on until eventually the input shaft sheered completely.

[squeezebm]

squeezebm said:

That is one of the funiest expert opinions on here re a/c for a while

You have in depth knowledge of refrigeration compressors then?

OP just pop it to the garage and get it looked at,as following some of the answers/advice you are getting on here will only leave you with more hassle.