2004 KJ AC Compressor Knocking

acdblujns · **Joined:** Sun Jun 11, 2017 10:27 am **Posts:** 3

Posted my question on another forum and had no takers. Hope you guys may have any ideas.

When using the AC on my 04 KJ there is a loud knocking noise coming from the AC compressor area when the engine is at idle. Turn off the AC and it goes away. That's the only time it does it. Otherwise, it blows nice & cold, and the knock disappears when the AC or defrost is on when at speed. Did my searches found all kinds of varying info from low freon to bad clutch or belt tensioner. I thought it could have been the belt tensioner going bad, but replaced it and still the same problem. Before I go and purchase a new compressor or clutch I'd like to hear of anyone else that's had the same trouble and their fixes.

Thanks,
Pat

GordnadoCRD · **Posted:** Sun Jun 11, 2017 9:07 pm

The compressor clutch should cycle on and off

Does it happen only when the clutch is engaged / only when the clutch is not engaged / or all the time?

acdblujns · **Joined:** Sun Jun 11, 2017 10:27 am **Posts:** 3

Knocks all the time when the AC is on and engine at idle.

Thanks!

GordnadoCRD · **Posted:** Mon Jun 12, 2017 8:47 pm

Have you checked the clutch mounting nut for proper tightness?
Or the AC clutch bearing for any movement?

That's where I would start.

I recall others having knocking noises that ended up being from being the belt tensioner and some from the crankshaft harmonic balancer, but not the specific circumstances that they occurred.

Low freon would cause less cooling ability, and you say it's working fine for cold.

acdblujns · **Joined:** Sun Jun 11, 2017 10:27 am **Posts:** 3

Ok thanks, I'll give that a shot and report back.
Thanks again,
Pat

2004 KJ AC Compressor Knocking

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