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Has anyone had a rear compressor issue with a new Yukon XL Denali? My wife and I bought the vehicle at the beginning of October 2018 and within a month the rear compressor began running excessively. We took it into the dealership with bought it from and the service rep heard the noise but was unable to reproduce it later in the day with the technician so they sent us away with the vehicle. The noise became more and more regular so we took it to a dealership near our house and they heard it and acknowledged the problem, this lead them to replacing the rear compressor. The change of the rear compressor didn't do the trick and the excessive running persisted, this is where the frustration really set in. The service technicians were going to run diagnostics and service the vehicle after we brought it in MLK Day. The service department manager interrupted the process and essentially tried to bully my wife into accepting the fact that this is normal behavior for a GMC Denali line vehicle. She left the dealership in tears. I called the service manager in disagreement with 1) his treatment of my wife and 2) disputing the fact this is normal. His response was the discharge the video with a bogus report emphasize the vehicle was in intended working condition. Now the Denali is sitting at another dealership while they try to replicate the issue. It occurs 30-40% of the trips we take in the vehicle and the rear compressor will run anywhere from a few seconds to 20 minutes. Has anyone else had this issue and found a resolution? I'm to the point I'm almost willing to just sell the vehicle back for a loss to be rid of it.

Hello all I'm new to this read forums my entire life when needing help on a issue someone had back in 99. But anyway I have a 2008 Yukon xl 5.3 bought it a few years back quickly realized there was a issue on top of issue. I got screwed and screwed big time. Truck was sold as 168k miles. It was clean nice good looking truck for 4800 bucks. Turns out won't go over 65. We'll we just said screw it and run it for a while until we got our excursion. So now I've been trying to fix it. I need help I've tried refresh at the dealer it sat there for a entire day in a bay with a tech and they couldn't figure it out. So back to the drawing board. Later on tried to trade it in they pulled the carfax trunk our dude swapped the cluster and it was said the last reported mileage was 278k. Well ******. I want to figure out why it will not surpass 65. It has all the gears. Engine has all the power. No limp mode no codes. I have even pulled the cluster and drove it and that didn't change anything. Please help. Thank you. Derick r.

Last summer I purchased a 2001 Yukon XL with the 5.3L engine, replaced the rear rotor/pads and air filter, then went on a 13,000 mile 8-month road trip starting in Boston, going through Maine, Atlantic Canada, back to Boston for a seasonable job, then to New Mexico via South, back again to Boston through the midwest and finally Florida to help my folks through covid (all safe). The truck now has 191K miles, but the original title indicated the mileage was not accurate (which is how I got it for $1,200 on eBay), so, who knows. The mechanic who did the rear brakes was surprised how little rust was in the undercarriage. I removed the rear seats, added a mattress and three milkcrates for my stuff, installed a cheap aftermarket radio with bluetooth and a rearview mirror camera. Brake and ABS warning lights were skillfully covered with duct tape by the previous owner, I removed the ABS fuse because ABS kicked in without need when breaking at low speeds (dirty sensors?). Over the 13K miles I had 2 oil changes + tire rotation at Wally, and poured Bar’s Leaks into the radiator to stop a slow coolant leak out of the intake manifold. I drove full tanks at different speeds on cruise and averaged: - ~13 MPG city - 20.44 MPG at 55 highway (sorry truckers, thanks for not throwing your pee bottles on my windshield) - 19.53 MPG at 60 highway - 18.81 MPG at 65 highway It’s been a hell of a truck, and now in Florida I have a garage + time, and will do some maintenance. Here is my list, I appreciate any suggestions (or requests): driver side rear caliper/pads/hose (the wheel is a little warmer than the others after driving, and it just started to whistle though pads/rotors are only 13K miles) front rotors and pads, total brake fluid flush check if front hubs need replacement (I occasionally hear a noise when turning left at very low speeds) oil change w/ amazon synthetic + mobil 1 filter trans fluid flush w/ Dexron VI, new filter, and tighten valve body bolts (sometimes tranny thumps from a stop after highway driving, but the fluid is still pink enough) spark plugs and wires (just tested resistance, 7 AC Delco wires are perfect, at about 660 ohms but the 1 shorter Denso wire is at 505 ohms; double platinum AC Delco 41-962s have some gray and orange and could probably go back, but I’ll change just because I went through the trauma of removing them - BTW, three out of the eight plugs have oil in the threads, should I be happy?) fan clutch (not a lot of resistance, and my ac belt “jackhammers” when moving from idle - which according to some of the forums might be due to higher freon temps at idle due to a dying fan clutch) fuel filter clean and seal all grounds both downstream oz sensors (voltage is getting lazy) I’m predicting that between the freed caliper, new plugs/wires, fuel filter, trans fluid and oz sensors I will see some mpg improvement over the next 10K miles, which will hopefully cover the Pacific Southwest, California and Pacific Canada. Thank you all for sharing you knowledge here, I look forward to putting it all into practice.