Odd AC issue on start-up

[UltimateToolReviews]

My 22 GMC 2500 gas seems to like to wait 20-40 seconds after starting for the AC to go cold in the morning. Also at stops and rarely low speed the AC will also stop for about 30 seconds or so, fan is still blowing, just not cold air. Never had a truck do this before, 95% of the time the AC works fine, but does seem to struggle a bit like my ram when temps get over 95f out. Should I try a recharge kit?

 

No lights on dash or codes from the scanner.

Edited July 28, 2025 by UltimateToolReviews

[UltimateToolReviews]

So I found a work a round, just run the AC in manual mode, it no longer has the delay on start-up doesn't seem cycle on/off at lights now. 

[jake111]

I generally hate auto climate control.  My old truck had it but when the weather was warm, it would blast the fan so loud you couldn't think.  After that, it would just do whatever it wanted and not necessarily what I wanted.  For 20 years it was always in manual mode (more like semi-auto because it still wanted to "help").

 

No problem in my new WT truck now!  Just turn the knobs left/right to get what I need.  Dual zone would be nice but this is good enough.

[UltimateToolReviews]

On 7/29/2025 at 2:46 PM, jake111 said:

I generally hate auto climate control.  My old truck had it but when the weather was warm, it would blast the fan so loud you couldn't think.  After that, it would just do whatever it wanted and not necessarily what I wanted.  For 20 years it was always in manual mode (more like semi-auto because it still wanted to "help").

 

No problem in my new WT truck now!  Just turn the knobs left/right to get what I need.  Dual zone would be nice but this is good enough.

I also discovered that whenever the AC goes warm, just hit the AC button off then on and it blows cold the rest of the day. I have done this twice now in over 100f heat.

[newdude]

Sounds like it could be low on freon or the compressor is struggling?  We had a rash of compressors on these lately in the 2020-2025 model year window.  

[UltimateToolReviews]

On 8/7/2025 at 4:15 PM, newdude said:

Sounds like it could be low on freon or the compressor is struggling?  We had a rash of compressors on these lately in the 2020-2025 model year window.  

Correct, I just dug into it futher today and discovered my 22 GMC uses R-134A (check your fan shroud sticker!) and so at idle on a cold start in 95F the compresser will not kick on at all unless you start driving. I found my freon to be definitely low (not getting worse, no leaks found, I assume under filled from factory) and added some and now it cools the vent temps to 60f at idle and 50s at highway speeds in 95f weather with no more warm air at stop lights.

[UltimateToolReviews]

Hopefully this is the final update, I added freon to the system again after checking over everything. Added freon the on the low side to 45 PSI, thats the max you should ever use in the system. It now gets cool in under 30 seconds at start-up, stays cold and the vent temp is now down to 46F at idle. It's 100% working now. I tested it for over a week, no leaks, freon is staying full. 

[bruceb58]

Hopefully, you have been adding pure 134A. You never want to use the cans that have the 134A and stop leak inside too.

[UltimateToolReviews]

On 9/22/2025 at 12:15 PM, bruceb58 said:

Hopefully, you have been adding pure 134A. You never want to use the cans that have the 134A and stop leak inside too.

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.