04 Jetta AC problem

Picked up an 04 Jetta TDI a month ago. 368K on the clock (TB & WP done 30K ago).

When I put on my AC I hear a chatter under the hood. AC does push out cold air.

When I took a look under the hood with it running and AC turned on u can see the accessory belt tensioner slapping back and forth making the chatter sound.

Is this a tensioner problem? Without AC on it seems calm and as it should be. Or is this an AC clutch problem or other AC problem?

Thanks in advance for your advice.

Kevin

Check to make sure your alternator pulley is working properly. When the ac comes on with the fans and blower it adds a decent load to the alternator.


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Make sure your cooling fans are working!
They should both be running when the A/C is on, otherwise the pressures will be too high while not moving. This could cause your compressor to be overloaded and 'squall' the belt.
I think there is a sticky on this very problem at the top of the forum page.
Other than that, I would check the system with a gauge set to make sure it's not overcharged.

Yes, good, you have cold air. Pop off the top engine cover, run the AC, use a stethoscope (or hose in ear) and isolate the noise. It may even be obvious visually. It could be the AC unit, but more likely something else in the serp belt system (tensioner, alt pulley) or ??