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AC compressor squeals like mad after putting on new serp belt- adjust or sticky spray

Sentinelist

Sentinelist

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If you may remember from my failed ATT install attempt, I did at least get my serp belt changed. Drives great. But in turning on the A/C (idle or at speed), it squeals like a stuck pig. I believe it's slipping. Is it normal to adjust the compressor after such a belt change, or should I just spray some sticky spray onto it for some bite? I've actually never heard of or seen the latter in an automotive sense but saw someone recommend it for a supercharger pulley on another forum I'm on. Thanks.
 
You have a problem that needs to be fixed. Belt dressing on a new belt may cover up the issue. Other than alignment there isn't anything to adjust and alignment isn't normally adjustable. Few suggestions off the top of my head.

Belt is too long. Defective, may have stretched, wrong length stamped on it... 1993 did not have a vac pump so it has the shortest belt vs. 1994 up. Do you have the old belt as a spare to compare? Mark the tensioner position and put the old belt back on to see any difference.

Compressor is locking/locked up. Including high head pressures from a plugged orface tube. Does it have 2 wires to a high pressure cut out switch on the back of the compressor as required for 134A conversions? (In addition to the 2 wire compressor clutch coil plug.)

Pulley alignment off. Something is too far forward or backwards to be in line with the other pulleys.

Tensioner is bad or the wrong part. Penetrating oil may free it up. You need to get new ones from the GM dealer as the aftermarket *cough cough A zone* will sell you a tensioner that uses the same weaker spring the later driver side AC compressor 6.5's use. (1996+?) The 1993 tensioner spring has to carry the AC compressor load so it has a stronger spring. The weak spring unit won't take the load and will squeal till you get the compressor spinning - can be done after a few tries. (It's late, the problem showed up 2 hours into the run, and it was 110 out. The belt and tensioner went back the next day...)

When it does run the slack in the belt can flap between the crank pulley and the AC pulley with a buzz. 454's had an idler below the compressor to cure the belt flap noise.
 
A lot of people said not to use the belt dressing.

It may work in the old way the belt was made but modern belt material is different.

x2 with WW on fixing the original issue.
There are a lot of part that goes DOA nowadays.
I have a new belt installed in my Toyota and squeal from the beginning.

If the old belt before you replace was good, try putting that back and see.
If it does not squeal anymore, the new belt is bad.
 
I purchased an autozone belt a while back and had the same problem. Would squeal like crazy if I even thought about turning the a/c on. Long story short I bought a gates belt from O'Reilly's and never heard another squeak.
 
When you run the defrost the compressor cycles and you might be able to watch it better. Or you could have someone turn AC on and off for you. Having a helper hold slightly different RPM's would be better.

Spray belt conditioner makes a mess but can temporarily help reduce belt noise just to help diagnose but it won't fix it.

Is your tensioner in the adjustment range and move smooth through travel?

Belt quality is very important! I have had mixed quality/performance from even the premium brands ordinary belts. If the belt has stretched and you need to replace it I suggest go to good parts store with experienced counter person and ask for the best belt possible ask for a premium or HD of a preferred brand.
 
Right on the can of 'belt conditioner', it says "do not use on serpentine belts". Just sayin.

Sent from my ADR6350 using Tapatalk 2
 
Thanks, guys. I think I have a bad belt- pulleys and all systems were working top-notch before I swapped it, so I have little reason to suspect anything but the belt. I'll try and return it and try that Gates belt from O'Reilly's next. This AutoZone belt seems like the right part and length (nice and taut when the tensioner is released, just like the old belt which is still fine and I kept as an emergency spare), so it's likely the belt quality. I'll post back later with results, probably in a week or two when I have time to get in there again.
 
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