2006 GMC Sierra

[Cusser]

However on 2 separate occasions now if I park the truck in direct sunlight where temperatures under the hood rise from sitting all day when I first crank the truck the relief valve on the compressor has popped and vented off freon on 2 separate occasions.

This is not normal. Attach some service gauges and get real readings of the high temperature pressures under such sitting conditions.

[tbirdtbird]

Gotta try to not park in the sun…..that is a killer

[JYarber]

It's a proprietary database from which I gleaned the 8.0 fluid ounces of PAG-46 for your truck. But AllData and Mitchell's reportedly have the same information. Last time I looked, you can purchase a short-term subscription to either one for just about any vehicle. They are the same factory sources that professional mechanics use and rely on.

Or you could just split the difference and make it 7.5 fluid ounces in total, which would be slightly too much or slightly too little, depending on how you look at it. IMHO, this amount would be acceptable since the difference is only a minuscule 0.5 ounce.

2-3 issues I am having that I would like your opinion on. Replaced all the parts a few weeks ago. Got the system vacuumed and recharged to the full required amount. AC was performing great. However on 2 separate occasions now if I park the truck in direct sunlight where temperatures under the hood rise from sitting all day when I first crank the truck the relief valve on the compressor has popped and vented off freon on 2 separate occasions. I have not checked the pressures since this happened but obviously it will have lower amount of refrigerant then required now.

Other issues I have noticed are sitting idle my AC is colder versus driving down the road and also it is colder on a lower fan speed versus max fan. Thanks in advance!

Bump

[JohnHere]

I suspect that a condensing issue might be the problem.

Does your vehicle have a viscous-drive clutch mounted directly in front of or directly behind the fan blades? If it does, those clutches tend to last only a few years before starting to give trouble. If your vehicle has one of those and you haven't replaced it yet, I suggest doing so as the next step.

If your truck has an electric fan instead, does it come up to full speed with the engine at operating temperature, the A/C system turned on, and the compressor engaged? If it doesn't, then you could have a "tired" fan motor, which might also cause the vehicle to run hotter than normal or even overheat.