My compressor squeels like a pig

[71CHEVYSHORTBED402]

It was rebuilt. The compressor worked for maybe 50 miles, it's basically a new 71 truck, running 134A in the system. Took it out today, turned on the AC and the compressor had a PIERCING HIGH PITCH squeal to it. The other day I ran it, started the AC and it smelled like a dead animal. Connection, I don't know, but there aint no dead animals in my system, probably

I noticed the belt was on loose, and with the AC on the compressor pulley fluttered with it. Hmm, how'd that happen. Re-tightened everything. Tension allowed for a 1/4 turn on the belt like I think it's supposed to. Wow, that worked. A whole 20 seconds and the belt's loose again. The belt has 100 miles on it. What the heck? It only squeals when the compressor is on.

[71CHEVYSHORTBED402]

Maybe I dodged a bullet, not holding my breath. Seems one of the bolts were a bit loose. Started all over again and it seems to be fine.

[franken]

So if the compressor makes a noise looking at the compressor and it's surroundings is a good idea?

[71CHEVYSHORTBED402]

Originally Posted by franken

So if the compressor makes a noise looking at the compressor and it's surroundings is a good idea?

What? I was going to delete the thread, but now I don't know

If you tighten it and it's not tight then tighten again. Heck I don't know.

[PbFut]

From the very little experience I have rebuilding my system...the compressor was pretty tight early on. (Very difficult to rotate the outer hub) It seemed to loosen up some after a couple hours of running. As for the belt. If new it may have simply stretched some. The tight compressor exacerbated the issue causing belt to slip. Tightening the belt corrected your problem initially. Maybe you failed to tighten enough and the set simply slipped some returning to a loose belt. There are five 3/8 9/16 head bolts holding my compressor in position. Your mount may be different. Easy to miss one when adjusting. All need to be loosened for the compressor to freely move for adjustment squarely to the blet line of travel. Then important all 5 are then properly tightened to keep things square and nothing slips..

[71CHEVYSHORTBED402]

Originally Posted by PbFut

From the very little experience I have rebuilding my system...the compressor was pretty tight early on. (Very difficult to rotate the outer hub) It seemed to loosen up some after a couple hours of running. As for the belt. If new it may have simply stretched some. The tight compressor exacerbated the issue causing belt to slip. Tightening the belt corrected your problem initially. Maybe you failed to tighten enough and the set simply slipped some returning to a loose belt. There are five 3/8 9/16 head bolts holding my compressor in position. Your mount may be different. Easy to miss one when adjusting. All need to be loosened for the compressor to freely move for adjustment squarely to the blet line of travel. Then important all 5 are then properly tightened to keep things square and nothing slips..

I suspect that's what happened thank you, one of the lower bolts wasn't quite tight when I re tightened it, only to do it again Has to be TIGHT short busting a bolt in a head, Yikes. Crossing my fingers. A BBC bolts like this for what worth, just happened to have it. Short answer is the BBC head takes five bolts as well.

The lower compressor bracket’s rear inside corner slides onto the stud securing the RH exhaust manifold’s front. The bracket secures to the stud with a 3/8”-16 hex nut and split washer. The bracket is faintly stamped; the last three digits read "269". Reference the exhaust manifold assembly for the stud.

• The bracket’s lower front corner secures to the head’s lower face with a (GR 5) 5/8" hex bolt and flat washer. The bolt threads are 7/16-14 x 1”, and the head is stamped "U". This bolts the negative battery cable terminal as well.

• The bracket’s lower inside secures to the RH head’s front side post with a (GR 5) 9/16" hex bolt, flat washer and split washer. The bolt threads are 3/8-16 x 1”, and the head is stamped “U”.

The front compressor bracket’s slot aligns with the lower bracket’s font hole. Both brackets secure to the RH head’s face with a (GR 5) 5/8" hex bolt, flat washer and split washer. The bolt threads are 7/16-14 x 1.1/4”, and the head is stamped “U”.

The accessories bracket’s top secures to the front compressor bracket’s face with a (GR 5) 1/2" hex bolt inserted from the front. The bolt threads are 5/16-24 x 7/8”, and the head is stamped with a dog bone. The bracket retains the 5/8” ID heater hose and the negative battery cable.

• The accessories bracket’s bottom and the front compressor bracket secure to the lower compressor bracket with one (GR 5) 9/16" hex bolt, hex nut and split washer, with the bolt inserted from the front. The bolt threads are 3/8-16 x 1.1/2”, of which 3/8" is shaft, and the head is stamped “P”.

The front compressor arm support secures to the RH head’s top inside face with a (GR 5) 5/8" hex bolt and split washer. The bolt threads are 7/16-14 x 1”, and the head is stamped with a triangle. The support is stamped with a triangle as well. The support’s top will position behind the front A/C bracket mounting the compressor flange’s top RH corner.

The compressor support rod bracket mounts using the RH exhaust manifold bolts located 2nd and 3rd from the front.

The compressor support rod positions with its slot facing up. The rod’s flat end secures onto its bracket’s front with a (GR 5) 9/16" hex bolt, hex nut and split washer, with the bolt inserted from the front. The bolt threads are 3/8-16 x 1”, and the head is stamped “U”.

The rear compressor arm support bracket mounts with two bolts and split washers mounting the intake manifold, located 2nd and 4th from the front. The bracket is stamped “3972726”. Note regular intake manifold bolts are flanged head 3/8-16 x 1.1/4”, and too short for this bracket. The bracket requires 1.3/4” long bolts where split washers are used. The bracket for this rebuild is mounted with two (GR 5) hex bolts and split washers. The bolt threads are 3/8-16 x 1.3/4”, of which 5/8" is shaft, and the heads are stamped "TR”.

The rear compressor arm support positions with its elbow facing up. The support secures onto the rear of its bracket with a (GR 5) 9/16" hex bolt, split washer and flat washer assembled from the rear. The bolt threads are 3/8-16 x 1”, and the head is stamped “U”. The support will position in front of the support rod mounting the compressor’s top rear inside.

The compressor plate mounts to the compressor’s lower rear with two (GR 5) 9/16" hex bolts and split washers. The bolt threads are 3/8-16 x 1.1/8”, and the heads are stamped “RSC”. The plate is stamped with a triangle, which faces out. Three factory shims install between the compressor and plate. The plate will mount the compressor to the lower compressor bracket.

The A/C Compressor then mounts as follows:

1. The compressor's flange positions over the front bracket’s face.

2. The compressor plate mounts to the lower compressor bracket’s rear with one (GR 5) 9/16" hex bolt, hex nut and split washer, with the bolt inserted from the rear. The bolt threads are 3/8-16 x 1.1/4”, and the head is stamped “RBM”.

3. The compressor flange’s top inside corner mounts with one (GR 5) 1/2" hex bolt, flat washer and split washer, with the bolt inserted from the rear. The bolt threads are 5/16-18 x 1”. Assembly order from the rear: Bolt > washers > front compressor arm support > front compressor bracket > compressor flange. Some suggest this flange hole has 5/16”-24 threads, perhaps there are variances.

4. The compressor’s top rear inside mounts with one (GR 5) 9/16" hex bolt, flat washer and split washer. The bolt threads are 3/8-16 x 1”, and the head is stamped “U”. Assembly order from the rear: Bolt > washers > compressor support rod > rear compressor arm support > compressor.

5. The compressor flange’s bottom inside corner mounts to the front bracket with a (GR 5) 1/2" hex bolt and split washer, with the bolt inserted from the rear. The bolt threads are 5/16-24 x 5/8”, and the head is stamped “D”.

6. The compressor flange’s bottom outside corner secures to the front compressor bracket with one (GR 8) 1/2" hex bolt, hex nut and star lock washer. The bolt threads are 5/16-24 x 1”, and the head is stamped “AS”. The bolt secures the compressor ground wire terminal and the accessories retainer as well. The retainer is faintly stamped with a triangle. Assembly order from the rear: Bolt > compressor ground wire terminal > star lock washer > front compressor bracket > compressor flange > accessories retainer > hex nut.

The A/C compressor belt runs from the compressor’s pulley to the water pump pulley’s front track, and to the crank pulley assembly’s middle track for a truck with power steering.

Reference assembly manual pages 525-527. Some of the bolt descriptions in this section are a best guess. The A/C assembly was removed long before this rebuild, though most of the hardware remained on the brackets. The balance of hardware was pulled from a 1972 C20.

[dmjlambert]

I had a terrible time with Autozone/OReilly store-brand belts the first couple years I had my truck. Now I decided if it's not Gates, it is not going on the truck, and that solved my flimsy belt problems, squealing, breaking, stretching, etc.