2017 GMC Sierra AC was blowing warm air so went to shop and hooked up gages to AC and just thought it was low so i decided to pull a vacuum on it and it held then put Freon back in the system and it started cooling just not like it did when i first got truck. about 2 week it started warming up so i added some more freon to it and it cooled down for about a week. after that i pulled another vacuum and added leak detector to make sure i didn't have a leak. Found no indication that i had a leak in the system. decided to change the expansion value pulled another vacuum on it and added freon to the system this worked for 2 weeks. so i decided to pull another vacuum on it and then decided to add stop leak to the system just in case i had a leak and didn't find one. the also worked for 2 weeks and now it is blowing warm air. i am working the AC button in the cab and it would start blowing cool and work while i am driving to work. once i leave work it is blowing warm air and i push the button again multiple times and it eventually start to work but not good. Tired of throwing money at this thing because we know that 1234yf freon isn't cheap and it takes 2.5 cans everytime you need to fill the system.
