I have been round and round with this belt tensioner for this 4.8.This is where i started. Ariund 75k miles i changed the main drive and a/c belts last Sept. The a/c tensioner started chattering under a load w/ the a/c on only. Does not happen when a/c off. I changed the tensioner w/ an parts store brand... broke the tensoiner after fifty-teen minutes, took it back for my money back. Put old one back on. I thought just b/c of a new belt that i would let it break in. March rolls around and time to start the a/c again. doing the same thing. I bought a gm dealer part and did not help also had to warranty the belt the aftermarket belt. The newbelt, new tensioner, new shorter belt(too small), and even shimming the compessor didn't work either. So.... does anyone have any suggestions?? need help and need a/c b/c it gets a little warm here in texas.

 

That is a common problem. I hate to tell you, but it's the a/c compressor you need to replace.

 

even if the compressor is cooling at 37* and is not make a sound except hearing it engage/disengage.

 

Turn on your a/c, when the compressor is engaged, rev up the engine. If it starts chattering/squealing/making noise-replace the compressor and you will need a new tensioner when the compressor is replaced because it has been beating the crap out of itself thanks to the compressor.

 

Replace the drier and orifice tube too.

He's right though, it's a common problem. There was a TSB released as well.

You weren't in a parts store asking about this a couple of days ago were you?? About a Tahoe your wife's driving ????