Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart C-10 - A/C Clutch Control CKT (4.3L "B" Body)
When A/C switch is turned on, ignition voltage is supplied to the pressure cycling switch through the control head. If there is a sufficient A/C charge, the pressure cycling switch will be closed to complete the circuit to the ECM and to the A/C high pressure switch. If A/C head pressure is not too high, circuit would be completed to the A/C clutch coil.
- Checks for short to ground in circuits No. 66, No. 67 or No. 1592 if fuse was open. Check for shorted compressor clutch coil. Check A/C system for further diagnosis of power feed circuit to the control head.
- Check to determine if ECM is capable of detecting A/C status.
- If A/C clutch engaged, check for 12 volt supply at ECM terminal B8. If voltage is present, a faulty connection exists at the ECM or ECM is faulty.
- Before replacing control head, perform thorough A/C system diagnosis.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.