Imho you should take it into a trusted shop. I own a 2016 Chev Silverado 4 × 4 LT True North edition w/ the 5.3L. I have babied it since brand new. I just took it into my local GM dealer for servicing after noticing the A/C had stopped blowing cold...turns out the A/C condensor was leaking due to a 'bad' factory weld and has since leaked out all of the refrigerant completely, leaving the system totally 'dry'.
It took almost 5 years for the weld to give out lol. That being said, I still have 2.5 years on the extended GM B to B factory warranty, so 100% of the parts and labour are covered on the installation, fill, and test of the new A/C condensor & system.
I've read numerous threads online stating that GM have had issues with the 2014 - 2018 model years of A/C condensors leaking, due to said 'bad' factory welds.
Hopefully this helps, and with any luck (if you have the +2 year extended warranty) you'll be able to 'gitter done for next to nothing at your local GM dealership.
Happy trails & good luck
MoonDogg