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A/C Belt chirps when compressor first engages [message #369566]

Tue, 26 April 2022 14:46

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

I finished rebuilding my dash air (new Sanden compressor, filter dryer, 18 ounces of Duracool & expansion valve + flushed lines, evaporator & condenser). I finished the day before we left on our current trip to Kentucky. It blows cold air and cools the cab sort of OK on the 80+ degree day we had on the way down. It seems to work as well as you can expect a type II system to work.

The only issue is the compressor belt will chirp a bit when the compressor clutch first engages during high way speeds. It does this once every 10 minutes or so which is annoying and potentially damaging to the belt. I am pretty sure the belt is not on tight enough.

I was in a hurry to get everything buttoned up before leaving so I didn't pay too much attention to the tightness of the belt.

There does not seem to be much information in the maintenance manual about belt tension, except:

"Using belt tension checking gauge BT-33-73F (Burroughs Tool) or other suitable gauge check
power steering belt (vehicles equipped with automotive air conditioning MUST have power steering belt
checked and adjusted if necessary first). A used power steering belt should be adjusted to 70-80 lbs.
A new power steering belt should be adjusted to 110-140 lbs."

No mention of air conditioning belt tension and I don't have that tool.

I always just tightened v-belts until they "felt tight enough" and that usually worked.

What do other people do?

Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.

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Re: A/C Belt chirps when compressor first engages [message #369567 is a reply to message #369566]

Tue, 26 April 2022 17:03

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

Richard,

You may not be aware that this is why early GM cars with A/C used the heater to temper the outlet temp as opposed to trying to cycle the compressor. It is also why the later A6 compressors all have that massive iron sheave to be a flywheel to get the compressor going.

Now that we have filled that in, you could probably tighten the belt enough to make it stop. I bet you don't have a belt tension gauge in your tool box and you can't find the app for it at the App Store. Try twisting the belt. If with bare hands, you can make it wind up more than 90°, it is too loose. That is worthwhile try, but only a possibility as the start slip you have been hearing may have already damaged the belt surface. It is still worth a try.

Another "cheap trick" would be to find a spray can of belt dressing. This stuff amounts to being spray on "sticky" that can improve the belt's traction in the groove.

I hope you have a boring drive home.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: A/C Belt chirps when compressor first engages [message #369568 is a reply to message #369567]

Tue, 26 April 2022 18:34

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

Matt Colie wrote on Tue, 26 April 2022 18:03

Now that we have filled that in, you could probably tighten the belt enough to make it stop. I bet you don't have a belt tension gauge in your tool box and you can't find the app for it at the App Store. Try twisting the belt. If with bare hands, you can make it wind up more than 90°, it is too loose. That is worthwhile try, but only a possibility as the start slip you have been hearing may have already damaged the belt surface. It is still worth a try.
Matt

I used to do the 90 degree twist thing back in high school and college until it was pointed out to me that it depends on hand strength. I used to wrestle in college and pretty strong hands. Back then a friend suggested between my hands and a normal girls hands the ability to go 90 degrees or more could depend on gender and/or hand strength. Probably by now my hand strength is the equivalent or less than a kindergarten age girl. So how good would not going to 90 degrees be as an indicator of belt tension? I better get another tool. One can't have too many tools.

Any way I tighten the belt as tight as I could go with a pry bar my son had in his garage. We will see if that is tight enough. The belt looks pretty good with no obvious signs of damage. I really didn't run it that much after the chirping started when the ambient temperature went down under 80. Higher than that the compressor didn't cycle that much. It only chirped at high way speeds when the clutch first engaged.

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Re: A/C Belt chirps when compressor first engages [message #369572 is a reply to message #369566]

Thu, 28 April 2022 02:25

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

Is it a new Sandeen with a new pulley? If so, the pulley width is probably to wide for the belt. Is the belt new too. How wide is the belt. I will bet one of them is incorrect. If either is incorrect you can hide the problem by going to the next wider belt size.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Re: A/C Belt chirps when compressor first engages [message #369574 is a reply to message #369572]

Thu, 28 April 2022 06:58

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

Ken Burton wrote on Thu, 28 April 2022 03:25

Is it a new Sandeen with a new pulley? If so, the pulley width is probably to wide for the belt. Is the belt new too. How wide is the belt. I will bet one of them is incorrect. If either is incorrect you can hide the problem by going to the next wider belt size.

Ken,
I had not thought of that. Yes the Sanden is new (pulley new with the compressor) but the belt is not. It worked with a previous Sanden. So that could be the problem. I'll measure those things when we get back.

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Re: A/C Belt chirps when compressor first engages [message #369575 is a reply to message #369566]

Thu, 28 April 2022 07:12

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

Matt, would not the heavy sheave - or any added mass - exacerbate a startup slip?

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

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Re: A/C Belt chirps when compressor first engages [message #369576 is a reply to message #369566]

Thu, 28 April 2022 07:38

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

Johnny, the heavy part is the large rotating pulley part of the clutch. Already rotating when the clutch pulls in the plate

John Lebetski
Woodstock, IL
77 Eleganza II

[Updated on: Thu, 28 April 2022 12:42]

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Re: A/C Belt chirps when compressor first engages [message #369581 is a reply to message #369566]

Sat, 30 April 2022 07:45

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

Aha!

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

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[GMCnet] Re: A/C Belt chirps when compressor first engages [message #369582 is a reply to message #369566]

Sat, 30 April 2022 07:45

gmc-email-list

Messages: 124
Registered: February 2019

Karma: 2

Senior Member

Aha!

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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[GMCnet] Re: A/C Belt chirps when compressor first engages [message #369589 is a reply to message #369582]

Sun, 01 May 2022 10:22

powwerjon

Messages: 849
Registered: March 2013

Karma: -2

Senior Member

I see that no one has replied to your email on your belt chirping on AC
pull in.

There is not necessarily one answer to your question.

1. Tired streated belt, glazed belt. Belt dressing can sometimes help, but
not necessarily for long.
2. Using one of the "NEW" metric 10MM belts or sometimes 3/8" can be the
only one available and all suppliers swear they will work. "SPOILER ALERT"
they don't! The original belts were 1/2" (13MM) wide and rode correctly in
the AC pulley.and crank pulley.
3. If you can find a Goodyear "Gatorback" or a Kelly Springfield and they
are 11+MM wide. Take a 10MM open end wrench to check the width. If the
10MM wrench fits over the belt then it will not work for long.
4. I rarely buy locally and get most belts online. vbeltsupply.com
5. For an Alternator belt I use an A56 belt (13MM) from NAPA or Farm and
Fleet. Some of the AutoZone Duralast belts are 11.176MM wide for other
belt locations. Check, Check, Measure and Measure!!!!!!

J.R. Wright
GMC Great Laker
GMCGL Tech Editor
GMC Eastern States
GMCMHI
TZE Zone Restorations
78 Buskirk Custom 29.5' Stretch
75 Avion (Under going Frame up Restoration)

On Sat, Apr 30, 2022 at 8:45 AM jhbridges--- via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Aha!
>
> --johnny
> --
> Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> I forgive them all, save those who hurt the dogs. They must answer to me
> in hell
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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Re: A/C Belt chirps when compressor first engages [message #369592 is a reply to message #369566]

Tue, 03 May 2022 09:22

rjw

Messages: 697
Registered: September 2005

Karma: 4

Senior Member

rjw wrote on Tue, 26 April 2022 15:46

I finished rebuilding my dash air (new Sanden compressor, filter dryer, 18 ounces of Duracool & expansion valve + flushed lines, evaporator & condenser). I finished the day before we left on our current trip to Kentucky. It blows cold air and cools the cab sort of OK on the 80+ degree day we had on the way down. It seems to work as well as you can expect a type II system to work.

The only issue is the compressor belt will chirp a bit when the compressor clutch first engages during high way speeds. It does this once every 10 minutes or so which is annoying and potentially damaging to the belt. I am pretty sure the belt is not on tight enough.

I was in a hurry to get everything buttoned up before leaving so I didn't pay too much attention to the tightness of the belt.

Thanks Matt, Ken, JR and others who responded to my question.

As it turns out I had an old compressor v-belt that was apparently too narrow. While at my son's place I tighten it as much as I could with what tools I had. From there we drove to a state park not far away and during that short trip the A/C cooled satisfactory but didn't sound quite right. But there was no longer any chirping.

After leaving that park we drove to a Harvest Hosts location near Cincinnati. Just as we were approaching parking I noticed a sound I had never heard before. I stopped and popped the hatch and noticed right away that the compressor belt was off and hanging between the fan and the engine. It was intact and after inspection it looked like it had been riding in or close to the bottom of the compressor pulley groove. It was a Gates 7612 XL and measured 10.21MM in width. Apparently too narrow and probably the cause of unusual sounds etc.

That belt had been on since 2012 (over 55,000 miles) but the A/C had not been functional for at least 5 years. We had been using house A/C during that time.

Now I need to figure out the correct belt to use with a Sanden compressor. Will a 15570 air conditioner belt from www.vbeltsupply.com work?

I knew about using a 10MM wrench etc. to check belt width, but it's been a long time since I last worried about the v-belts in my GMC.

I had other v-belt issues on this trip, but will start a new thread to discuss them.

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Re: A/C Belt chirps when compressor first engages [message #369824 is a reply to message #369566]

Tue, 31 May 2022 19:11

Scott Nutter

Messages: 782
Registered: January 2015
Location: Houston/San Diego

Karma: 4

Senior Member

Richard,
The AC belt I use on my 455 with the Sanden compressor is part number 7597. That should cross reference at whatever parts place you go to. I use Gates from napa.
Scott.

Scott Nutter 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI Houston, Texas

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Re: [GMCnet] Re: A/C Belt chirps when compressor first engages [message #369825 is a reply to message #369589]

Tue, 31 May 2022 21:14

blur911

Messages: 166
Registered: December 2020
Location: Kingston, Ontario

Karma: 4

Senior Member

powwerjon wrote on Sun, 01 May 2022 10:22

3. If you can find a Goodyear "Gatorback" or a Kelly Springfield and they
are 11+MM wide. Take a 10MM open end wrench to check the width. If the
10MM wrench fits over the belt then it will not work for long.

Goodyear Gatorback no longer exists in that name, they are now Continental and are the same 11mm Gatorbacks with a new name. (It used to be Continental Elite, now I think it might be all of them)
I recently picked up some when NAPA didn't come through.

Anyhow, someone mentioned a 59.5" belt for a Sanden, the Gates 7597, that would be a Continental 15595, which is an 11AV1500 size.

It's also 2.5" shorter than regular, which is the 15620, so is the sheave smaller diameter?

Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie

[Updated on: Tue, 31 May 2022 21:24]

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