Engine Size: 6.0 lit.
2005 GMC Yukon Denali AC belt breakage issue, 6.0 liter gas engine. No work EVER done on its AC system previously, 164K miles.
A few weeks ago my small (separate) AC serpentine belt had just snapped after 3 years (Gates) on our GMC, no signs of slippage or wear, clean break. The AC compressor readily turned by hand (seemed normal) and the little tensioner pulley also was smooth and silent. I replaced the AC belt with another Gates belt, since everything else seemed OK, and AC seemed to work fine for a few weeks, but yesterday the new small AC belt broke again; this time the AC belt tensioner pulley doesn't feel so good. I looked this up on Google and this is a known GM issue, even a TSB. Any thoughts? How could the compressor be slugging when it has same refrigerant/oil as it's had in the past? Thanks.
A new Gates AC tensioner assembly is like $35, seems a lot less involved than anything involving the AC compressor, think I want to go that path and try that unless I hear something here.
Edited: Thu July 16, 2015 at 2:35 PM by Cussboy
Ever hear of an AC compressor deslugger timer? Like Murray # 36141 ? http://www.oreillyauto.com/site/c/detail/MRY0/36141.oap?year=2005&make=GMC&model=Yukon%2BXL%2B2500&vi=1440609&ck=Search_36141_1440609_2823&keyword=36141
Yes I have! 4 seasons has one as well. I understand what they claim to do and help correct. They claim to keep the compressor from slugging while trying to compress oil upon starting the compressor. I'm like the idea, but am not sold on it yet.
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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!
GM Tech - can you please add input whether 2005 models still had this AC compressor slugging issue ? Thanks. I see the TSB came out in October 2004, so of course that would not include 2005 models !!!
Cussboy,
Kinda "semi-retired" from A/C work, but my grown daughters don't seem to understand that!
The GM silverado's they own, and my own 98 Suburban and 94 GMC seem to keep me "in the loop".
I've had some experience with the slugging issue on the GM vehicles.
As I see it, there are actually two causes of the GM belt breakage issues WRT computer slugging.
1. There was/is an issue with the rear unit models suction line back to the compressor. Can turn off the air flow through the rear unit, but the TXV can't really turn off the refrigerant flow through the rear evap core. If the fan isn't blowing, there's little evaporating going on in the core and some liquid get through the core and back to the compressor. I don't know of any rear "cure" for this except to leave the rear unit on LOW when not needed.
2. Low sitting compressor gets sluggeg by liquified refrigerant that pools in the compressor during "off" time. I recall a "fix" (I think by GM) to open the accumulator fitting port that goes to the compressor and drill a small hole in the pipe that you find inside the fitting of the accumulator. This is supposed to be a vacuum breaker that prevents sucking liquid refrigerant out of the bottom of the accumulator and into the compressor. Never have had the need for this one, although I have replaced a few compressor belts with the Gates Razorback that seemed to overcome the belt breakage problem..
Ac_Doc
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Sometimes you must accept things at faith value!
We do leave the fan on for the rear evaporator, learned that from radio mechanic Mark Salem's show. That does make some sense.
The issue I'm having is definitely slugging, evidenced by the tensioner wear, and the noise while running, and of course the repeated belt breaking. So for me it's only going to be masked/delayed if I find a belt "better" than the Gates I have used.
If this new compressor lasts half as long as the original one, I'll still be happy; with our 1988 and 1994 Suburbans, lucky to have a compressor last 3 years (but those were R4 compressors, and they were mounted high).
I'm planning the compressor job (along with the deslugger accessory) for the weekend of Aug. 1
Edited: Fri July 24, 2015 at 12:40 AM by Cussboy
Here's a new AC tensioner top v. the original one on the bottom. See how the "stop" metal on the bottom one has been worn away? That's positive evidence of compressor sluggage, just like the flyer in the Gates tensioner box shows. New Denso compresser goes in this weekend.
Edited: Thu July 30, 2015 at 9:45 AM by Cussboy
If its slugging- then it does it constantly-- that stop is worn away from extreme rattle and/or vibration- Have you seen my video- it is not a once a day thing- it is harmonics/rattle rpm related- that goes on forever...
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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
No, I'm not aware of your video...the noise happens at about 1800 rpm only when the AC is "on", and not all the time. But I can't just keep replacing belts every 2 weeks either, so I need to try something that might help. Do you have any suggestions? I'm open to fixes you may suggest.
Edited: Thu July 30, 2015 at 2:53 PM by Cussboy
The rattle video is on this thread
http://www.autoacforum.com/messageview.cfm?catid=2&threadid=21029
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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
OK, I watched that video twice. Maybe I didn't get my rpm up high enough, but I didn't see my own tensioner dance like the one in your video. But I still don't need Mrs. Cusser about the belt breaking and AC not working every two weeks. I was fortunate that O'Reilly honored the warranty on the Gates belt, has 3-year warranty, but doubt that will cover frequent replacements due to an external problem.
We're in Arizona, it's freakin' hot here, often the LOWS are over 92F, and still can be over 100F after midnight, so I need a longer term solution. Which looks like it worth it to try a new compressor. Besides: its compressor pulley bearing seems to be a little looser by feel than what I'd like.
"Of course" the new Denso compressor didn't come with O-rings, guess that's a cost savings thing, thanks Denso !!! Does anyone know off-hand what diameter and thickness these need to be, or maybe I'll just have to take the new compressor to CarQuest and guess on the thickness. Thanks.
Of course I really won't KNOW the absolute correct size/shape until the existing compressor comes out. I don't know if it takes standard-shape refrigeration O-rings or those special metal/rubber ones. Maybe someone can post a link or picture of the compressor fittings O-rings. Thanks again.
Edited: Fri July 31, 2015 at 11:03 AM by Cussboy
UPDATE:
Yesterday I recovered the refrigerant, and installed the new compressor
yesterday. The Denso instructions detail to measure the amount of oil remaining
in the existing compressor and subtract that amount from the oil amount already
in the new Denso compressor, but only about 1/3 of an ounce of oil came out,
even when I had it upside and rotated the compressor/pistons 10 revolutions. So
I didn't pull any oil out of the new Denso compressor, installed that with new
O-rings, wired-in and mounted the Deslugger timer on the firewall, evacuated the
system an hour, pulled over 29 psi vacuum. Then I did vacuum test, held vacuum
without a drop for over half hour. I added back the refrigerant I had
recovered, used an electronic scale to measure that, and made up R134a
difference using two 12-ounce cans, to get to the required 48 ounce capacity
(sticker inside engine compartment). I only use pure R134a, no sealers and no
conditioners. I did NOT replace the orifice tube or the accumulator, as the AC
performance had convinced me those were still OK.
Pressures after the repair were similar to those measured before the refrigerant
removal: 40 psi low side, and 255 psi high side. I took the Yukon on a test
drive, measured down to 37.9 degrees F in center vent on a 3-miles drive. No
noise from AC or tensioner dancing, so right now I'm happy. Yes, the new
compressor cost me $215, the Deslugger timer $38, the Gates belt tensioner $35,
and new Gates belt $25, and the R134a was about $8 a can.
So at the moment I consider this project a success.
9 days later and after at least 400 miles of driving in the Arizona heat, Mrs. Cusser states no noise, no tensioner "dancing"/rattling, and same good AC cooling in the Yukon, great news.
Replaced were compressor and tensioner, and AC Deslugger compressor timer/protector device added.
Cussboy,
Good information to know.
How many wires to hook up on the Deslugger - 3 I bet.
Cut the wire going to compressor coil.
Wire to compressor to one terminal.
Other end of compressor wire to second terminal.
Ground wire on deslugger.
I read where this deslugger is a timed pulser than moves the clutch in little increments for a minute to purge the cylinders of liquid without breaking anything, Then allows normal operation.
I might put one of those on my GMC!!
AC_Doc
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Sometimes you must accept things at faith value!
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