A/C Belt Breakage

jsmca22 · July 31, 2005

I have a 2000 Z-71 that keeps snapping A/C belts, I have replaced 7 in the past 6 months. The original lasted 3.5 years, since then it has been a nightmare. The AC Delco belt seems to last the longest. The snapping occurs at various time, hiway speed, idle, I have tried turning the A/C off after each trip and not starting with the A/C on but it doesn't seem to matter. What can be causing these belts to snap so often??

mmmikkke · July 31, 2005

I have a 2000 Z-71 that keeps snapping A/C belts, I have replaced 7 in the past 6 months. The original lasted 3.5 years, since then it has been a nightmare. The AC Delco belt seems to last the longest. The snapping occurs at various time, hiway speed, idle, I have tried turning the A/C off after each trip and not starting with the A/C on but it doesn't seem to matter. What can be causing these belts to snap so often??

<{POST_SNAPBACK}>

I'd suspect either a misalignment or an accessory that's failing (e.g. your a/c compressor). Another possible cause is excessive belt tension...make sure your tensioner is moving freely (while no belt is on it).

GM-Tech · July 31, 2005

I want to say it sounds like a compressor locking up briefly, but I would think after six months, it should have failed totally by now or at least cause more frequent problems.

jsmca22 · July 31, 2005

I was told by a mechanic that GM is aware of this but has not posted anything on it because they fear liablilty would cost them. I was told the compressor is probable the problem, my only thing is the A/C works fine other that snapping a belt. The tension pully is free and movement is easy by hand. The last belt I personally changed on Friday this past week and I was able to use my hand to pull the tension pully down to get the new belt on. If it is the compressor, why and what would cause it to lock up even if it just for a second or so??

mmmikkke · July 31, 2005

I was told by a mechanic that GM is aware of this but has not posted anything on it because they fear liablilty would cost them. I was told the compressor is probable the problem, my only thing is the A/C works fine other that snapping a belt. The tension pully is free and movement is easy by hand. The last belt I personally changed on Friday this past week and I was able to use my hand to pull the tension pully down to get the new belt on. If it is the compressor, why and what would cause it to lock up even if it just for a second or so??

<{POST_SNAPBACK}>

I think...I think the compressor is a 3-piston unit. I think it's a lot like a 2-stroke engine, the crankcase has the low pressure refrigerant/lubricant, and 3 pistons send it to the high-pressure side of the system through reed valves.

I think that the rings can wear out, eventually reducing compressor efficiency, and increasing friction in the 3 cylinder walls. That puts additional strain on the compressor crankshaft, and so it starts to wear out also. You can usually "hear" a compressor failing, as it develops a knock.

Depending on where it comes to rest, the failing compressor probably takes a lot more torque to get moving. So maybe 1 time out of 5, when the compressor clutch engages, your belt get stressed beyond its design strength, and it starts to fail also.

That's a fair bit of conjecture, though. Anybody know for sure?

jsmca22 · July 31, 2005

If all you say is accurate, wouldn't I be loosing cooling somewhere? The unit cools just fine and I haven't noticed any knocking of any kind. The unit has never been serviced as far as needing a charge or anything, would you think I might try to discharge the unit and re-charge it with new coolant and oil? I'm at a complete loss here, I just know I am tired of changing belts!

GM-Tech · July 31, 2005

I was told by a mechanic that GM is aware of this but has not posted anything on it because they fear liablilty would cost them.

Was this just something he dreamed up, or does he have some facts to back up his statement? I suspect it's a personal opinion. What liability? This is hardly a safety issue.

As for your tensioner... if you can pull it down with only your hand to put the belt on, you have a problem there.

jsmca22 · July 31, 2005

I'm not saying it was easy, I just put my two fingers in the pully side groove and pulled it down long enough to get the belt in position, should it be harder than that to do?

GM-Tech · July 31, 2005

I'm not saying it was easy, I just put my two fingers in the pully side groove and pulled it down long enough to get the belt in position, should it be harder than that to do?

Hard to judge from what you're saying, but I think it would be rather difficult to do with just your hand.

jsmca22 · July 31, 2005

Could this be causing the belt to snap, they are not melting apart from a compressor or clutch stopping, they appear to be snapping in two from a sudden jerk or something. Is there a way to check the amount of tension the belt should have on it? or is there a way to check the amount of tention the tension pully should be applying?

mmmikkke · August 5, 2005

Could this be causing the belt to snap, they are not melting apart from a compressor or clutch stopping, they appear to be snapping in two from a sudden jerk or something. Is there a way to check the amount of tension the belt should have on it? or is there a way to check the amount of tention the tension pully should be applying?

<{POST_SNAPBACK}>

I'd check to see if the belt is threaded on the correct side of all the pulleys. If it's on the wrong side of one or more pulleys, it might explain why it's so easy to push the tensioner down. Tensioners usually have a hole or boss to accept a pry bar or a 1/2" drive breaker bar. That's how much force they usually need to move out of the way of the belt.

Trotorx2 · August 5, 2005

A friend of mine has the same problem with his 2000 GMC ECLB 4.8 2wd. He finally went and got the next larger belt and hasn't had any problems since. I don't know where or what P/N belt he got but it is working fine.

jsmca22 · August 5, 2005

Thanks to everyone for their insight, I think I will sell the dang thing let someone else deal with it, I'm tired of sinking $$ into something that can't be fixed without trying this or trying that, it ain't suppose to be rocket science to be able to fix a Chevy!!!

binmanbill · August 8, 2005

I have the same problem with my 2003 Sierra.

The A/C works fine, but the belt will snap in half.

This only occurs under 30 MPH or when sitting still at a high idle.

I believe the problem is the compressor locking up as the internal pressure mounts.

I think at higher speeds (over 30mph) the airflow across the condensor helps keep the internal pressures lower. Prior to the belt breaking I get a agressive belt chatter and if I turn off the A/C quickly enough I can save the belt.

Is it possible the expansion valve might be sticking closed when ther eis limited air movement over the condensor, thus causing the increase in pressure.

The unit works likes brand new at highway speeds and I think I could drive forever without breaking the belt. It is just at low speeds, and usually happens when the unit has been driven a short time, shut off and then restarted. Like a trip to the store. When restarted and driving away at about 20 MPH the chatter occurs and then the belt breaks. It is a clean break, just like it snapped in half. I have replaced the tensioner, as I thought this might be the problem. Didi not make a difference.

Any thoughts?

GM-Tech · August 8, 2005

I have the same problem with my 2003 Sierra.

2003 is a known issue, but he's got a 2000. Here's the TSB. Perhaps applying it to the 2000 would help. Don't really know...

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Underhood Rattle Noise Heard on Acceleration (Check A/C System Performance and Compressor Operation) #03-01-38-019A - (Sep 3, 2004)

Underhood Rattle Noise Heard On Acceleration (Check A/C System Performance and Compressor Operation)

2003-2004 Cadillac CTS

2002-2004 Cadillac Escalade, Escalade EXT

2003-2004 Cadillac Escalade ESV

2002-2004 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe

2002-2004 GMC Denali, Denali XL, Savana, Sierra, Yukon, Yukon XL

2002-2004 Commercial Upfitter Chassis Vehicles

2003-2004 HUMMER H2

with Air Conditioning (A/C)

This bulletin is being revised to update the service procedure and parts information. Please discard Corporate Bulletin Number 03-01-38-019 (Section 01 -- HVAC).

Condition

Some customers may comment about an underhood rattle noise heard on acceleration or a sudden loss of A/C system performance.

Cause

This condition may be caused by liquid slugging of the A/C compressor. This condition may cause an internal failure in the A/C compressor. The serpentine belt tensioner and serpentine belt may also be damaged.

Correction

Technicians are to check the A/C system performance and compressor operation using the following repair procedure:

Open the hood and inspect the A/C compressor for damage and to see if the compressor is seized. Verify that the serpentine belt is not damaged or missing. If the A/C compressor is seized, proceed to step 5.

Perform the A/C System Performance test. Refer to the Heating, Ventilation and Air Conditioning (HVAC) section of SI. Correct any performance concerns or refrigerant leaks that are found.

Inspect the vehicle for other possible sources of A/C compressor noise or performance concerns. Refer to Corporate Bulletin Number 01-01-38-013 for more information.

After all other possible sources of A/C compressor noise or performance concerns have been eliminated, only then should the A/C compressor be replaced.

Remove the A/C compressor. Refer to the A/C Compressor Replacement procedure in the HVAC section of SI.

Inspect the transmission cooler lines for damage due to contact from the serpentine belt. Replace the transmission cooler lines if necessary.

Install an inline A/C system filter. Refer to Corporate Bulletin Number 01-01-38-006C for more information about A/C system flushing and filter installation procedures. An A/C system flush is not to be done unless prior authorization is given by the GM Area Service Manager (in Canada, the District Service Manager).

Install an A/C Suction Screen. Refer to Corporate Bulletin Number 01-01-39-003A for more information about A/C suction screen repair recommendations and procedures.

Install a new A/C compressor. Refer to the Compressor Replacement procedure in the HVAC section of SI.

Install a new orifice tube for the front A/C system. Refer to the Expansion (Orifice) Tube Replacement procedure in SI.

If the vehicle is a 2003 model year Chevrolet Express or GMC Savana van, the vehicle may require a new accumulator. Refer to Corporate Bulletin Number 03-01-38-016 for more information. This bulletin refers to an updated design accumulator that may improve the performance of the A/C system.

Install a new serpentine belt tensioner and serpentine belt if they have been damaged due to A/C system slugging or an A/C compressor seizure. The serpentine belt tensioner may have broken stop tabs and/or a missing front cap.

Verify proper operation of the A/C system.

Parts Information

Refer to the GMSPO parts catalog for the latest service replacement compressor part numbers.

Part Number

Description

Qty

89016656 (*A/C Delco Part# 15-10413)

Universal In-Line A/C Filter

1

Parts are currently available from GMSPO.

*This filter may also be purchased through your local A/C Delco distributor.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

D4440

Compressor Assembly - Replace

Use published labor operation time

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

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