UltimateToolReviews

Well the dealer quoted $3200 for the compressor and this shop normally charges $2000, but they did all of the other work for free, plus a discount on the compressor so I came out way ahead at $1800. They stand behind there work really well.

I updated my post above, the AC issue went way deeper than I thought, it ended up being the compressor electronics, so full compressor replacement anyway.

Update (see below for my original post) - Alright so the pressure switch and low freon fix both helped the issue, but very quickly the AC started the delay issue again. Ugh. So I took the truck to a HD truck repair place about 5min from me, these guys are awesome, all they work on is HD trucks so I trust them more than the dealer. NOTE - Already did the pressure sensor and found the low freon issue and added freon before this. Day 1 - diag'd as a bad control assembly (dash knobs), they said it's common and they do those often. $800 qoute, 2-3 hours should be back up and running quick, part took 3 days to arrive. Day 4 - These guys actually tested the truck out in the heat, I don't mind the extra testing, that way they actually figure it out. Well low and behold, now it's the expansion valve, ok cool, they give me discount and said it will be ready pretty quick, but of course they test it in the heat hard before letting me pickup the truck. Qoute is now $1100. ($300 more for the expansion valve isn't bad) Day 6 - Nope, bad news again, issue is still there. But good news, is an electrical issue with the compressor. Compressor can get the vent temps to 42f no problem, but at idle or cold start it quits. Now they are doing the compressor. I was pretty sure based on what I've read on forums and FB that the compressor had some issues in these trucks and the new versions fixed this. Day 8 - Finally fixed, total cost for everything was now $1888, they ate a ton of the labor thankfully. Honestly cheaper than I had thought, I thought it would be just the compressor and I expected $2000ish. Original post below So my truck had low freon from factory, easy fix myself, but I had this really weird delay when starting the truck that started right after that, the AC would blow hot for 3-10min every time, then go cold BUT stay cold as long as it stayed running. No codes, nothing. GMC couldn't figure it out, and just said replace the compressor but I found a post on FB were a guy said both of his GMCs AC died at 50k miles and the GMC dealer replaced a "sensor". Huh, ok, that sounds easy, now the pressure sensor for these trucks is right by the compressor, not easy to get to(or even find at all!), but also still a 5min job. The part is hard to find, my dealer said is was not even available, however Rock Auto had them HERE for $26 bucks shipped. Its a 5min job, but you must do a full reset of the AC system, pull the battery for 3 min and its good to go. I did a complete video guide but I won't link it so as not to break any rules here.

OK just did the job, here is what I learned for anyone future reading this. 1. Very easy overall, step 1 pop hood, clean around brake fluid res and open cap, place on top. Also no service mode needed on these (2500+3500 only) 2. I used 2x Bremen 12 inch bar clamps from HF, compressed the calipers fast and easy 3. I deleted the sensors, so I disabled them in the settings first, then just took the old sensors and zipped tied them out of the way(3 zip ties each), super easy and didn't cost anything. 4. my brake fluid res was overfilled when i done, I removed some before starting or opening a door on the truck to just below full. 5. That's it, took about an hour total, brakes are way better now, no squeal and they bite much better!

Less crap the better, I only buy lower trims because I don't want cool seats, sun roofs, etc. I work on my own trucks and want them to stay working. Brake sensors are so silly.

Same reason here, lol. Brakes squeal like crazy.

Cool, just figured it out. Thanks!!! For anyone in the future reading this to figure it out, start the truck, go into the i (info page on the dash), scroll down to brake life (scroll all the way down to edit page an enable the page if you can't find them) and click on it, if will give you the option to disable the system. I recommend doing it before touching the brakes at all.

So I am seeing a ton of conflicting info on doing the brakes on these trucks, anyone have a complete step by step from GM? I've heard you need to use brake service mode, but I've also heard you only need to do that on the 1500s. And do you need remove some brake fluid before compressing the pistons for the new pads? Also do you have to run the brake life sensors or can those be left off? Any clear help would be awesome! I've got the new pads but don't want to mess anything up here.

I don't think you could do it in 30min, but my mechanic friends say it's about a 2 hour job, just awkward but not hard. Normally runs around $1000-1200 for a shop to do it.

Only checking in the morning cold and in the same parking spot, so no issues there. Not worried about overfill on these huge v8s, you can overfill probably 2 quarts and not see any issues. These aren't BMWs.

So I wanted to closely monitor my oil use in this truck, since it's the only real issue with this engine anyone talks about and hopefully put some people at ease. I've owned other HD gas trucks and they all use some amount of oil, especially when working hard, it's normal for any brand. Here is the math I did Oil change at 46900, put in 8.4 quarts on propose, to get to the top of the cross hatch, exactly 8 quarts will only get you the middle of the cross hatches on the dip stick. Checked oil at 49350, so 2450 miles driven under mixed loads, towing 12k, hauling 2-4k in the bed, highway at 70-80mph and lots of city driving in hot FL, but little idle. Dipstick was at 1/2 cross hatch, added 0.4 quarts exactly to bring it back to the top, wanted an exact read on how much it used. That comes out to 0.16 quarts used per 1000 miles or 0.000163 quarts per mile. I do my oil changes at 3000-5000 miles. To get the oil low message on the dash you need to be 2-3 quarts low, which if you do a 8.4 quart change you would need to drive around 17,000 miles on my truck. Not something I would ever do. So if your checking and changing your oil like you should, 3000-5000 miles and doing the math on any oil use you can figure out pretty quick if your L8T is having oil issues. This oil use is right on my par with my 2019 6.4 Hemi, nothing unusual for an HD gas truck that works. Also I use Kirkland oil from Costco and filters from Walmart.

Your on the track, after you have the spoiler off, clean the channel with the window and cab really good, and just fill it up with flowable silicone, I used 2 full tubes from an auto parts store, it will never leak again.

Yup, no additives in the cans, just pure. Also one more update for this thread, after topping off the freon, the auto AC works perfect now, zero issues.

Same here, trying to find a good solution or replacement still.

275/65/R20 is the size, same as stock but heavier of course a little going to the Wildpeaks. I think most stuff wasn't greased on the truck, first thing I did was grease it everything.