AC compressor knock at idle

So for the longest time, whenever I have the AC on and after driving a bit the compressor will knock only at idle. Give it a little throttle and it stops, let off and it's back. All fasteners are tight and the pulley nut is tight. Lines looked like they are routed fine. If I put my hand on the compressor while it's knocking, I don't really feel the knock. This is telling me that maybe the clutch is failing or has play in it when engaged?

I searched the forums and didn't really find anyone else with the same issue. Was just curious before I buy a new clutch and pulley assembly.

Other than the noise, the AC works awesome! I did read that and overcharge could cause the compressor to make noise, so I evacuated and recharged but still there. Also vacuumed the system and re-oiled the compressor.

It could be the compressor is getting worn out.

When the car is idling with the AC on how does the belt tensioner look? It shouldn't move around much.

-J

How is your alt pulley?
It might be locking up and releasing at idle giving you that noise.

What Steve said.

Make sure you're looking at the right thing....

compu_85 said:

It could be the compressor is getting worn out.

When the car is idling with the AC on how does the belt tensioner look? It shouldn't move around much.

-J

Click to expand...

AC off or on, it bounces a little bit but not too much.

csstevej said:

How is your alt pulley?
It might be locking up and releasing at idle giving you that noise.

Click to expand...

Genesis said:

What Steve said.

Make sure you're looking at the right thing....

Click to expand...

I'm positive it's not the alternator pulley. Its new INA along with a reman alternator. But I have taken the belt off and verified its working correctly

New compressor and knock is completely gone.