When the A/C is switched on a rattling sound is heard at the front right, but when the engine is revved up (from 900 rpm up) the rattling sound is gone. It comes back when the engine is idle @ around 750rpm. Any ideas what this might be? Is it something I could ignore if I switch the A/C off?

Thanks.

 

Sounds like the same problem as in this thread..

https://www.jaguarforums.com/forum/x...-rattle-96857/

 

First of all thanks for your quick reply. The rattling noise comes after the A/C is switched ON. Is it the same thing? Excuse my ignorance if I am asking the same question.

 

Could be..maybe the clutch is going to hell too...But you won't know until you get wrench on the clutch nut...see the discussion on the other thread..hope your problem is a simple fix.

 

First, tighten the clutch to 10ft/lb. If that doesn't work, you will need a new compressor

 

I am not a air conditioning guru but I have good luck with noisy compressors with first putting a gauge on (low side, small scrader valve) to see if it's low on R134A then I add a 4 OZ can of oil/134A with air on max cold, fan on medium speed directed through dash vents( not defrost or floor). It usually quiets them down. NO MORE than 4 OZ though.If the pump isn't shot it won't hurt if it's shot who cares. Other than that there are 50 other things that could be the problem and it takes a GOOD tech to diagnose. Don't spend a ton of money on freon cause your probably just making it worse by over charging the system. It could be air flow,stuck valve, ect.If the compressor engages there is SOME freon in the system, if it cycles on/off it's low.Other than that it's a crap shoot without the proper gauges and expertise. BE careful the HIGH side (large scrader valve)has high pressure and will blow these cheap gauge/hoses that you buy at auto parts stores right off.

 

I had a problem like this several years ago and after I added some compressor oil it largely went away and A/C works just fine.