minhc_88

Hi everyone,
I've been chasing this issue for a few weeks now. Any advice would be much appreciated.
Idle RPM fluctuates slightly and tensioner pulley vibrates (more aggressively) when I turned on the AC compressor. At first I thought It was a worn out Tensioner pulley, replaced tensioner pulley, idler pulley and serpentine belt, still no fix. Also noticed my Crank Harmonic Balancer pulley was wobbling like crazy, replaced that and idle felt smoother but still had the Tensioner pulley vibration.
Spark plugs and ignition coils are all fairly new, Vanos Solenoid and MAF sensor recently cleaned so car runs sweet as it should with the AC turned OFF. Vibrations comes on with AC turned ON.
I thinking/hoping its the AC compressor pulley that's causing this tensioner to vibrate as that's cheaper then a new AC compressor. AC compressor recently had full recharge done and is blowing super cold air.
Can bad bearings in the AC compressor Pulley cause vibration? Turning AC on demands higher load on the pulley bearing, which turns to more violent vibrations on the tensioner pulley?
Is there anything else I haven't taken into account?

donpb

Sounds like A/C compressor is failing.

kd7iwp

It has a separate belt for the AC compressor like the M54 does, right? Remove that belt and see if everything runs smoothly. The AC compressor won't engage though. You could then spin the AC pulley and see if it is smooth. Perhaps could apply voltage to the clutch to engage it and see how hard it is to turn the compressor but I've never done that before and don't know if it actually tells you much.

donpb

I have an N52 like @minhc_88 and it just has a serpentine belt.

minhc_88

Slight vibration even when AC compressor OFF due to variable displacement compressor. I might take the cover off sometime when I got time to see how the dampers in the pulley looks. Pulley doesn't make any noise, just vibrations on that tensioner.

seanjordan20

That's a good indication the tensioner bad. That would of been my first guest but you e changed that already. What brand tensioner did you put on

minhc_88

It was INA brand off FCP Euro. They pretty reputable and seem to have good quality stuff.