| A/C noise when off [message #145292] |
Sun, 02 October 2011 19:01  |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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I've noticed that when the dash A/C is turned off after running that a slight brushing noise occurs, some times it goes away and other times is just gets quieter, but recently is getting louder. I'm assuming that it is the air gap between the clutch and pulley, is this something to be concerned or is it more deep seated like the clutch bearing going bad. I've never experienced this before and pose these questions for someone with more knowledge and experience and hopefully give me some advice on what to do and what to look for.
Thanks,
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: [GMCnet] A/C noise when off [message #145300 is a reply to message #145292] |
Sun, 02 October 2011 20:16  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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John,
Do you or any of your friends have one of these:
http://www.harborfreight.com/mechanics-stethoscope-41966.html
They are very handy for finding the source of strange engine noises.
You can use a long screwdriver too but this is much easier.
Regards,
Rob M.
-----Original Message-----
From: John Blankenship
I've noticed that when the dash A/C is turned off after running that a slight brushing noise occurs, some times it goes away and
other times is just gets quieter, but recently is getting louder. I'm assuming that it is the air gap between the clutch and
pulley, is this something to be concerned or is it more deep seated like the clutch bearing going bad. I've never experienced this
before and pose these questions for someone with more knowledge and experience and hopefully give me some advice on what to do and
what to look for.
Thanks,
--
John
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: A/C noise when off [message #145301 is a reply to message #145292] |
Sun, 02 October 2011 20:40 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Can you tell where the noise is coming from?
Is it the compressor itself? If so, I would suspect the bearing in the clutch. I replaced mine several years back without removing the compressor and loosing the Duracool. It probably is easier to remove the compressor to replace it but you will have to vacuum it and recharge the system when you are done.
That's my first guess.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: A/C noise when off [message #145325 is a reply to message #145301] |
Sun, 02 October 2011 23:19 |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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Senior Member |
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Yes it is coming from the front of the compressor as in the clutch, pulley area, sounds like a rattlesnake. If the compressor hasn't run the noise is gone, but after you run the a/c and turn it off then frequently the rattlesnake, slight grinding sound is there. The noise is kind of like holding a screwdriver lightly to a pulley. Other than that the a/c works great, with normal compressor noise when the a/c is running. I don't know that the noise goes away when the a/c is running as the noise would be drowned out by the regular compressor noise, it is that low in volume.
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: A/C noise when off [message #145332 is a reply to message #145325] |
Mon, 03 October 2011 00:45 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I still suspect the bearing in the compressor. When the compressor in on, the clutch is clamped together and the bearing is not spinning. It only spins when the compressor is stopped and the pulley is spinning with the engine running. If it is the bearing it will get worse over time and you will soon know for sure. At least it will not leave you broken down beside the road. If it quits completely simply remove the belt and go on your way without AC.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: A/C noise when off [message #145340 is a reply to message #145325] |
Mon, 03 October 2011 07:44 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| jtblank wrote on Mon, 03 October 2011 00:19 |
Yes it is coming from the front of the compressor as in the clutch, pulley area, sounds like a rattlesnake. If t he compressor hasn't run the noise is gone, but after you run the a/c and turn it off then frequently the rattlesnake, slight grinding sound is there. The noise is kind of like holding a screwdriver lightly to a pulley. Other than that the a/c works great, with normal compressor noise when the a/c is running. I don't know that the noise goes away when the a/c is running as the noise would be drowned out by the regular compressor noise, it is that low in volume.
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| Ken Burton wrote on Mon, 03 October 2011 01:45 |
I still suspect the bearing in the compressor. When the compressor in on, the clutch is clamped together and the bearing is not spinning. It only spins when the compressor is stopped and the pulley is spinning with the engine running. If it is the bearing it will get worse over time and you will soon know for sure. At least it will not leave you broken down beside the road. If it quits completely simply remove the belt and go on your way without AC.
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John,
KenB, is probably correct in his diagnosis as that is about exactly what mine did. The only difference was that mine made horrendous noise (just short of panic level), then it seized a broke the belt. When I opened the engine hatch and saw what had happened, we went on our way to a great evening.
AZ has the needed pullers and pushers in their loaner tools collection (real low numbers, but I don't remember them). You can call and order the bearing, then borrow the tools and change it out in their parking lot. It is that simple. You do have to dismount the pump enough to get at the clutch front, and you will have to remove all the belts to replace that one (if you wait until it seizes).
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 noise when off [message #145343 is a reply to message #145292] |
Mon, 03 October 2011 08:23 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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John,
If you have to replace the bearing... here are the tools I used..with prices and sources. Autozone did have the bearing in-stock.
http://www.gmcmhphotos.com/photos/showgallery.php?cat=5593
Good luck,
Dennis
| jtblank wrote on Sun, 02 October 2011 19:01 |
I've noticed that when the dash A/C is turned off after running that a slight brushing noise occurs, some times it goes away and other times is just gets quieter, but recently is getting louder. I'm assuming that it is the air gap between the clutch and pulley, is this something to be concerned or is it more deep seated like the clutch bearing going bad. I've never experienced this before and pose these questions for someone with more knowledge and experience and hopefully give me some advice on what to do and what to look for.
Thanks,
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: A/C noise when off [message #145344 is a reply to message #145343] |
Mon, 03 October 2011 08:34 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Thanks to Ken B's insistance, we replaced the bearing in mine when we swapped compressors a couple of months back. Got the tools at Napa because AZ did not have all of them, where we were at the time.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
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