AC Problem, need trouble shooting guide?

[Hey you]

Looking for a good all in one trouble shouting guide for my 15 Tahoe LT. It started acting weird a week ago, but I could always get cool air if I played with the
switches. Power On / Off, Same for Recirc, On / Off with the rear system, Adjusting Temp selector to hot, then back to cold, and it usually would start working.
Yesterday I took it to Wally world, they had it hooked up to a tester for over an hour. Finally they said its done, Thinking I would have the problem fixed....
That was wishful thinking, they said the compressor is shot and they could not repair it.
So I started checking circuit breakers. Found 4 that tested good. 1 under the hood, 2 under driver side by door, 1 under passenger side by door, and 1 in the
rear compartment.
I read there is a reset by pressing the AC and Recirc for 10 seconds. Have not tried yet, sounds too good to be true.
Other things I want to look at are the pressure switches, hi and low. Can you safely remove them, without draining the refrigerant
Thanks in advance... just hoping I do not have to replace the compressor.

 

[PG01]

Cool air or cold air?
Does the rear ac get cold? Doesn’t matter what the front is set to check your rear a/c, if it does get cold and stays cold that means compressor is working
There are issues with the condensers in these years 15-17ish where they crack and leak. Your system could be low and the compressor will short cycle giving short bursts of ‘cool air’ so it may be coincidental that by playing with your switches you can get ‘cool air’
air temp out the vents should be cold with the temp set fully on cold not ‘cool’

 

[Hey you]

The rear AC does not get cold. I went to Firestone, they found the condenser fans not working. Ordered new ones, "twice" they thought the first replacement faulty. But
even the second set did not work. Bench check (should have done this first) revealed both new sets and my original set work fine! They suspect there is communication
between the dash controls and the components under the hood. Maybe a faulty circuit connection. I did not ask if they checked the condenser, but they did do a visual on
it. I am going to another facility tomorrow, for a complete checkout.
To think two weeks ago, the AC was ice cold, and now nothing!