“I feel that life is measured in achievement, not in years alone.”
“I feel that life is measured in achievement, not in years alone.”

The air conditioning in my S80 is out. I turn on the system, and the compressor clutch does not engage. It’s almost certainly a leak, but I want to check the wiring before buying a manifold gauge set. Below is the pertinent section of the wiring diagram.

Illustration for article titled Oppositelock, Teach Me About Relay Circuits
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The important components are...

  • 2/22 Relay
  • 8/3 Compressor

When I turn on the ignition without starting and jump terminals 3 and 5 on the relay, the clutch engages; that part works as it should. I also pulled the relay and verified it works.

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With the car on and the air conditioning switch on, terminals 2 and 3 light up a test light. Terminal 1 does not.

I think this all points to the ECM not sending a signal to engage the clutch. Am I missing something?

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