AC clutch not engaging

[Schurkey]

Pins? In the backside?

Is this automotive diagnostics, or vehicular acupuncture?

Maybe the answer is "yes".

Example--one of dozens.
www.amazon.com/Lisle-65150-Flexible-Back-Probe/dp/B00RGNFAMC/ref=sr_1_4?crid=2I2JCELNXJC98

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[GreenMonkey]

Thanks for all the input guys. I’m going to pick up a probing tool this weekend if I can find one and follow the procedures y’all wrote. I’ve never been great with electrical issues, so hopefully I’ll learn some things in the process. Will post back with results. Thanks again

 

[GreenMonkey]

Finally got some time to get back on the truck. Tested everything y’all recommended. Compressor engaged when ran directly off the battery and switches were testing good. So I took it by a buddy’s house who has gauges and evacuation system. Turns out I have a Freon leak and that was the problem. Just wanted to follow up with the post and say thanks for the help. I learned some things in the process and I’ll get it fixed next spring.

 

[8thNote]

I recently got the AC charged in my 98 k3500. I drove it home from the shop and everything worked great. Got in it a few days later and the air wouldn’t get cold. The compressor wasn’t engaging. My knowledge is limited on AC issues, but here’s what I tried. First, i tapped on the relay, then swapped in a known good relay from another gmt400. Still not working. I checked the fuse on the side of the dash, and the two in the engine bay fuse panel. They all looked good. Then I bypassed both the low and high pressure switches and it still wouldn’t engage. Next, I tried getting power directly from the battery to the compressor with no luck. Is it possible that I lost all my Freon in 2 days of sitting? I don’t see anywhere that looks like it leaked out (no dye on anything). And is there anything else I can easily check before taking it back to a professional. Thanks in advance.

To test your compressor, first find the low pressure switch (aka cycling switch) onthe side of the accumulator in rear passenger side of engine compartment

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Then unplug the harness from the switch. Take a paperclip and shape it into parabola. With the engine running and ac turned on high, stick the ends of the paperclip into the two sockets of the harness.

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If the compressor is good, it will immediatly kick on when the two sockets are bridged with the paperclip.