PSP grinding noise with AC on

[bavaria75]

Anybody can tell me the relation between the PSP and the AC???
If driving with "ECO" (AC off) the car steering is smooth no grinding and the Power Steering Pump seems to work easy.
If switching on the "Auto" (AC on) the PSP seems to work hard when steering and starts to make a whine or grinding noise.
My technicial understanding is that the V-Belt should be the only relation between the two and I believe the 3.0L engine should pull the AC and PSP without problems.
AC blows nice and cool
Steering is not effected just not as smooth and the noise.

Any input is highly appriciated.
Thank you, Tom

A4, 3.0 Quattro Manual Sportpackage. 87K miles

[gtimart]

One thing that comes to mind for the PS pump noise would be low oil level. I don't see a link with the AC compressor but I would still check it out.

[bavaria75]

gtimart, thank you for your input. Should have mentioned it. Steering fluid is filled to max at cold switched off engine.

[gtimart]

Then I would lean towards your AC compressor, not the PS pump. Does the sound change when you rev the engine (not moving the steering) ?
Or maybe your belt is slipping when the AC compressor puts additional strain on it ?

[Frey7190]

You know I have the same issue.. The other day it was 100*F here in Southern Cal and I turned the A/C on to LOW and the engine compartment started to make a funny noise and the moment I would turn it off the noise would stop. I did feel the steering be a bit weird so since I had no idea what the heck was going on I decided to roll with the windows down.... Any ideas anyone? I too would love an answer so I can fix this.

My A4 is the 3.0L with Front track, Sport pkg with 60k


Also I did notice that even on LOW the air wasn't really cold, maybe 5-6 degress colder than the outside air, what could that be??

[bavaria75]

hey gtimart,
I did rev up the engine at a stop without steering. Actully id doesn't matter if the engine idles or rev the noise is none existing. Just if I steer, the noise is there. If reving up the engine and steer, I'm not certain about the noise, but the steering feel is still rough.
Don't know about the v-belt slip on how to check. Looks used with some marks, but not worn. Marks are on the outside, where the roller only touches.
I guess I will investigate more later this week.
Thanks again.