A/c weird issue

[Tf79]

Especially in hot temps, unless on the highway all the time.

In Tennessee, hottest it’s been is probably 96ish. Highway at 55ish everyday but won’t overheat if I’m in traffic or in the city

 

[justirv]

2004 Yukon Denali. Already did an evac and recharge, no leaks with the dye we installed. A/c on first start when it’s hot won’t work, compressor kicks on but kicks off. Rev it to 1k, it noticeably kicks on for 15 seconds, cold air, then kicks off, warm air. One truck starts moving it works great ice cold. When I come to a stop it works, not as cold but it’s definitely working. When I get home and put it in park it works. Turn truck off and back on it works. Button turns compressor on and off correctly. It only doesn’t work when it’s hot out and on first start up. I’m so lost lol anyone have this issue before?

Confirmimg your rig has front and rear air? Did you weigh in your charge after a good and proper vacuum test? I have found my front/rear setup really touchy on weight, where adding an ounce or two will "all of a sudden" kick it on, and all is good. Definitely get some gauges on it, record low and high pressure, check ambient air temp, and refer to gauge psi/temp to verify you dont have non-condensibles in there. Let us know what you find.

 

[Tf79]

Confirmimg your rig has front and rear air? Did you weigh in your charge after a good and proper vacuum test? I have found my front/rear setup really touchy on weight, where adding an ounce or two will "all of a sudden" kick it on, and all is good. Definitely get some gauges on it, record low and high pressure, check ambient air temp, and refer to gauge psi/temp to verify you dont have non-condensibles in there. Let us know what you find.

Will do thank you

 

[OR VietVet]

Dealer did a evac and recharge. Changed the schrader valves. Nothing else wrong in their opinion. Ambient temp is around 90 when it happens. I’ve been watching a bunch of videos trying to learn how this system operates so I can see what else might cause it. No overheating issues, and fan clutch has been swapped. It only happens when I first start the car after work. Overnight it’s fine. You think they didn’t do the evac correctly?

So, let me get this straight. It only happens after sitting all day in the heat at work but when the vehicle sits in cooler temps overnight, it is fine? A/C does not blow cool/cold air immediately, especially after sitting in the sun/heat. It takes the air in the vehicle and absorbs the heat and gets rid of that heat at the condenser and recycles the air/refrigerant back and it is cooler. As the process continues enough heat is removed and the air is colder and colder. If the system starts with cooler air, then it gets colder faster.