A/C leak fixed system will not accept charge.

[Geotrash]

Got it. Probably best the cans did not go in because if I did it without reading this no doubt there would be air in the system. I have 4 cans 12oz each. I read the Tahoe's with rear a/c take 48oz for a complete charge from empty. Am I filling according to weight or pressure or both? I did not replace the accumulator. There are a bunch of Tahoe's at the local upullit yard. But I bet you are going to say that accumulator is a part that must be purchased new.

James' guidance is correct. And there should be a yellow sticker you can double check against that lists the refrigerant capacity on the top radiator support under the hood. You're filling according to weight, and the pressures should correspond or there is a problem in the system. And yes, the accumulator should be new if you're going to replace it (always a good idea on an older system), but beware that aftermarket parts are usually undersized and not good replacements for OEM in this case.

 

[j91z28d1]

Accumulators are cheap and considered disposable. that's where all the desiccant is. it helps keep the system dry. it should be replaced any time you open the system. even the accumulator is shipped under vacuum and shouldn't be opened till you're ready to install it. less time collecting moisture from air the better.


find the sticker for the amount of frezon to add on your specific truck. I've found book specs aren't always right and even then I've see a tsb over riding what the hood stickers say, because turns out the factory overcharged them.
it's by weight not pressure. pressure tells you a lot but starting from the correct charge by weight allows the pressures to tell you something. without knowing the charge, you don't know if the pressure is reading what it is for a reason, or just under or over charge.

Moisture in the system is very bad for ac, it lowers the efficiency of the cooling, which I get most people that have gone without it for a while don't care about that. but it also mixes with the oil and 134 and makes some bad stuff. it will kill the system eventually, how long that takes, its hard to say. could be a year, could be 5 or more. so I get with a diy repair it doesn't always matter. Just want some cool air for the simmer and deal with it later. but try your best within reason to do keep it clean.

 

[AnimalMother]

Thanks to your help I have ice cold a/c in the Tahoe. Part of the problem was a faulty R134 can tap valve that I purchased as part of a kit from Amazon. The piercing needle was a bit short and not depressing the valve in the top of the can far enough. So luckily Harbor freight sold that valve tap individually.
I shutdown the low side blue valve at the manifold and purged the yellow line when a new can was hooked up, as suggested. So no atmospheric air in the system. The system took 4 12oz cans of r134a. Ambient temperature yesterday was 71 degrees and the low side pressure was 40psi, high side pressure was 195psi when finished. I found it helpful to place the cans in warm water half way into it when the sun was going down. Must be cautious if you use water. Hot tap water is fine. Boiling water will over pressurize the can and you will suck the refrigerant out of the system back into the can followed by the can bottom going from an inney to an outy. Or so I have herd, wink.

Now I have to do the same procedure to my BMW X5. Armed with knowledge learned on this forum that project should be a piece of cake. On the other hand it's a BMW. Nothing is a pice of cake to fix. Thanks again.