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.
1991 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE
A/C Clutch Relay
- The A/C clutch relay is controlled by ECU. Under normal conditions, ECU will engage clutch relay by providing a ground circuit for relay windings. If ECU receives a wide open throttle signal from throttle position sensor while it is also receiving a A/C on signal from A/C Auto Amplifier, ECU will disengage relay.
- A/C clutch relay (Blue or Green) is located in relay box on right side of engine compartment. Relay is in rearmost position.
- Remove relay from relay box. Apply ground to terminal No. 2 of relay. See Fig 1 . Apply battery voltage to terminal No. 1 of relay. With relay energized, continuity should exist between terminals No. 3 and 5. No continuity should exist with relay de-energized.
Factory Service Tools
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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.
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