Hello all,

I'm a bit stumped with my 2000 ZR2's current issue. I bought it cheap a few months ago knowing it needed work, and I'm just now getting around to the little stuff like AC. When I switch to MAX AC or AC, the clutch doesn't engage. I went through the standard troubleshooting for this situation, starting with bypassing the low pressure switch. This had no effect so I bypassed the relay. The clutch engaged and the AC compressor kicked on, pouring beautiful cold air into the cabin for a few seconds. So I ran up to the store and bought a relay, but upon install it did nothing. I even returned it and got a second one to try on the off-chance that it was a dud, and double checked the pressure switch with the new relay to see if it was a combination of issues, still no dice. The terminals inside the fuse box are intact and in good shape, undamaged.

So I have ruled out the pressure switch, relay, and possible fuse box damage. Has anybody had issues with their HVAC control switches working in every mode except AC? Admittedly, AC units aren't my forte. For some of you who have been through AC troubleshooting and diagnosis before, what was your order of operations? Should I start out checking the pressure to begin, and then check the resistance or voltage to the AC switch? Thank you in advance.

On a side note, I did begin my day with searching this forum for my specific issue regarding AC, and did not find a post with my specific issue.

 

Should start by having a trusted shop evacuate the system and start there. You'll find out real quick if your system has a leak or not. If your system holds vaccum then get it charged. If all that fails then I would look into tryna figure out where it's not getting voltage. Also you have multiple power feeds for hvac I believe that you said you jumped the relay, there's 2 more hvac small tab fuses in the same fuse box aswell as 1 or two in the fuse box inside the cab(driver side dash, you'll have to open the door to remove the panel cover. Hope this helps

 

What year Is your truck?

if you had a leak then most likely bypassing the low pressure/cycling switch would have started the compressor, and if you had a bad leak then no cold air.

Did the compressor or cold air stop on it’s own or because you stopped bypassing the relay?

Did you check to see if the relay is being energized with a call for cooling yet or did you just route power to the compressor through the relay contacts?

George