Not sure but A/C is out?

[BowtieFever17]

It was just filled up.

[Aerofxr]

Just wanted to offer something I've discovered with my 91' K2500 Silverado with a 350 while t/s my a/c for leaks, fixing it, and then re-filling it. I don't know when GM did this but I've read it was in the 90' to 93' models. But later models probably have a more complex variation of it. If the pressure runs low and the compressor starts cycling too many times a signal is send to the ECM to not allow the compressor to engage. (I don't think 91' had a dedicated a/c module back then) The sign that that happened is that the letters "AC" on the temp control display on the dashboard will start blinking on and off. The oft used trick of jumping a wire between the contacts of the low pressure switch connector on that component mounted on the firewall (accumulator?) to get the compressor to engage won't even work. But when I disconnect the negative for a few seconds it resets the whole thing and the compressor will start engaging and start swallowing the "freon". Sometimes it will "lock-up" again while filling from cycling again and I have to turn it off and disconnect the neg. again but as the pressure builds it will stay on. Just for good measure I'll disconnect it one more time after I've put enough coolant in just to make sure it's starting on the "0" cycle count.

I know this probably doesn't ably to newer trucks but it might help with older trucks having issues with the compressor not engaging when you're trying to put some "freon" in it.

BTW it was either converted to 134a from "freon" before I bought it or it was 134a from the factory. 91' was one of those years when it could have been either but someone may know better..