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.
A/C Request Signal
The A/C system can be engaged by pressing the A/C switch. The A/C switch will illuminate when the A/C switch is pressed to the ON position. The MAX A/C, front defroster and defog mode selections will also automatically run the A/C compressor. The A/C LED will not illuminate in these modes of operation. The HVAC control assembly sends a A/C request message to the Body Control Module (BCM) which sends a class 2 message to the Powertrain Control Module (PCM). The A/C compressor clutch relay control switch in the PCM closes creating a ground and energizing the A/C compressor relay coil which closes the A/C compressor clutch relay switch energizing the A/C compressor clutch.
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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.