AC 3-10min Delay on cold start - NIGHTMARE ISSUES!!! (2020-2023 trucks)

UltimateToolReviews · May 19

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.

Edited May 28 by UltimateToolReviews

asilverblazer · May 22

On 5/19/2026 at 11:23 AM, UltimateToolReviews said:

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.

Wonder if the "full reset" without the sensor replacement would have fixed it.

Curious to, if the sensor replacement required a vac and recharge of the refrigerant?

Is this the high pressure switch, low pressure switch, or mysterious pressure sensor?

UltimateToolReviews · May 28

On 5/22/2026 at 5:19 PM, asilverblazer said:

Wonder if the "full reset" without the sensor replacement would have fixed it.

Curious to, if the sensor replacement required a vac and recharge of the refrigerant?

Is this the high pressure switch, low pressure switch, or mysterious pressure sensor?

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.

asilverblazer · May 29

On 5/19/2026 at 11:23 AM, UltimateToolReviews said:

...I took the truck to a HD truck repair place about 5min from me, these guys are awesome...

...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.

...GMC couldn't figure it out, and just said replace the compressor...

They don't sound that awesome to me, replaced a bunch of parts that didn't fix the problem, meaning they didn't need replaced in the first place. All just to end up where GMC recommended originally.

I'd be pretty irritated, wonder what the cost would have been for just the compressor.

At least its fixed now. :thumbs:

UltimateToolReviews · May 30

21 hours ago, asilverblazer said:

They don't sound that awesome to me, replaced a bunch of parts that didn't fix the problem, meaning they didn't need replaced in the first place. All just to end up where GMC recommended originally.

I'd be pretty irritated, wonder what the cost would have been for just the compressor.

At least its fixed now.

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.