2005 GMC Yukon Denali AC belt breakage issue

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 at least until 2004, 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. 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

The new AC tensioner did not help; an insert in its box showed photos of a tensioner damaged by compressor slugging, and my tensioner looked exactly like that. So rather than risk damage to AC system (was still cooling great) orifice tube or accumulator, I have ordered a replacement Denso OE compressor ($208) and a deslugger timer ($38) from Rock Auto. We need the AC here in Arizona, and our summer is 9 months long.

So I'm waiting for those, right now the AC compressor fuse has been removed so no additional damage can occur. Ignoring this would result in continued belt breakage, and eventual (maybe soon) compressor destruction, could even crack the compressor case and take out the automatic transmission lines worst-case scenario.

Compressors breaking belts constantly are all over the Internet, and the TSB from 2004 says to replace the compressor. The issue is due to a design flaw where the compressor is located lower than the rest of the system; however, it did last 164K miles, way longer than the R4 compressors on my 1988 and 1994 Suburbans...

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.
http://i613.photobucket.com/albums/tt211/Cussboy/DSC04925_zpsyz3bcxr0.jpg

OK, brief re-cap, 2005 Yukon 1500 6 liter, 158.1K miles. I rarely drive this,
she tows her horse trailer with it. In June, Mrs. Cusser reported occasional
noise when using the AC, said noise was underdash on passenger side. Early
July, Mrs. Cusser reported no AC, I found the separate little AC belt broken
(38-month old Gates belt) so I replaced the belt. AC worked great, two weeks
later that belt broke too, she said occasional noise when AC was on.

There's an October 2004 TSB talks about this, fix is to replace tensioner and
compressor; 2005 not mentioned, but TSB older than the Yukon. New Gates
tensioner did not help the issue, so I took out the compressor fuse. I ordered
a new OEM Denso compressor and a Deslugger timer. Dancing or erratic tensioner
movement due to bad compressor is not uncommon as a GM Tech has reported and
posted in this video, see the link halfway down here in this thread
http://www.autoacforum.com/messageview.cfm?catid=2&threadid=21029 We need AC,
and couldn't handle repeated belt breaking or having the system get contaminated
due to just ignoring the compressor/tensioner noise.

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.


=============
I installed the new AC belt tensioner and new belt; the system still makes the
noise sometimes, like about 1800 rpm, I don’t feel like just ignoring it until
it seizes or gets particles all throughout the system. Since it still cools
great, I think that I can get by with just replacing the compressor and leaving
orifice tube and accumulator in place.

The tech rep from the deslugger company said that it would not help a system
already slugging, that the damage has been done. Also, the AC tensioner
included photo of tensioner damaged by slugging, and my tensioner looked just
like that; I’ve included that bulletin as an attachment. So I think it’s best
to replace the compressor now, before more damage is done, like broken case
taking out transmission lines, whatever. I can get Denso new OE compressor
shipped for about $220, not bad. I think TSB #03-01-38-019A - (Sep 3, 2004)
didn’t go up to 2005 because it was issued before 2005.

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.

Mine was caused by the AC compressor. I had to replace that and I also replaced all of my AC parts back in 2010. No problems since.

Congratulations on your success. It's been fascinating reading!

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.

Update on the 2005 Yukon HVAC system:

The AC compressor, tensioner, small belt I installed last August (and deslugger) all seem to be working fine.

Last year in my limited driving on that I had noticed that the AC changed by itself to heat on driver side, and there was clicking under middle of dash. One could stop and turn engine off and that would re-set. Apparently this is due to a faulty door/flap actuator under the dash, and is a common problem on Yukons, Suburbans, GM trucks. So I took off the underside cover, of course being GM the innermost bolt was like impossible to get to, dug out a 7mm deep socket and was finally able to get that (read posts about folks having issues with that, and just leaving that screw or cover off). Anyway, that actuator has 3 positions, and I got it into the AC mode and then unplugged the harness so we'd have AC. But it turns out that this meant no heat.

Santa brought Mrs. Cusser a new aftermarket Dorman actuator ($50, why buy more-expensive GM again when there is a trail of bad ones posted on Internet?), and I braved our 45F wind-chill yesterday to install it, actuator is held in by 2 hex head screws. Well, once again, cannot access one of the screws due to the center hump being in the way, what terrible engineering. The screws take a 5.5mm or 7/32 inch socket, and I had to grind down BOTH ends of the socket to shorten it (recessed, so no access to use an open end or box wrench, had to use the ground-down socket and a 1/4 inch ratchet wrench; no room to fit in a thumbwheel-type 1/4 inch ratchet either
http://www.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_15157.jpg

Anyway, (using online instructions) I set the flap to align with the position of the new actuator, and bolted that in, reconnected the harness to the actuator, reconnected the battery, waited a few minutes, turned the ignition switch to on for a few minutes so computer could learn stuff, then switched ignition off for 10 seconds. So now we have both heat and cooling. I left the lower cover off, don't see any real reason to reinstall that.


Thanks again, GM !!!! What a poor design. I know a shop gets $300-$400 for replacement of these, had it done at a shop on the 1994 Suburban, and remember the mechanic saying how much of a pain it was !!!

Good, that part restored full operation, so that's great. Yesterday I re-attached the bottom cover, mainly so I didn't have to store it or throw it out.

Yes: I did NOT try to reattach the cover screw that is obstructed by the hump - again !!! two screws hold that cover fine, no need to even put a 3rd $^*&%^#@%^&$# screw there where hump makes it tough to R&R, guess I could have ground shorter a 7mm socket for that one. Thanks, GM.

Update: 3 years later, still working fine.