Hi,
You are connecting pin 85 (which you said is ground) to the negative terminal on the battery? That really won't show anything.
Okay, I attached the wiring schematic below for the circuit. Pin 30 should have battery voltage at all times. Pin 86 should only have power when the key is in the run or start position.
Pin 87 is power out to the compressor clutch, so it won't have power until the relay is actuated.
Pin 85 is a the ground path provided by the PCM to complete the primary side of the relay which then closes the switch on the secondary side powering the clutch.
So, confirm power is where it needs to be. Then, take your test light and place the alligator clip to the battery positive. Then, with the AC requested on and the key in the run position, probe pin 85. If the PCM is providing a ground path, the test light should turn on.
Let me know what you find. Also, here is a link that you may find helpful:
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
Let me know.
Take care,
Joe
See pics below. Note: I had to cut the schematic in half to make it readable. I did overlap the two and highlighted the related wiring.
Images (Click to make bigger)
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Sunday, July 30th, 2023 AT 10:33 PM