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.
Air Conditioning Signal: MDX
2004 Acura 3.5RLSECTION MDX
- Start engine. Turn blower on. Turn A/C on. With the Honda PGM Tester or the HDS, check A/C CLUTCH in the DATA list. If it is on, go to next step. If it is not on, see appropriate HVAC SYSTEMS-A/C PRESSURE SWITCH TEST article in AIR CONDITIONING & HEATING.
- Check the A/C system. If it is operating properly, the A/C system circuit is OK. If it is not operating properly, go to next step.
- Turn ignition off. Turn ignition on. With the Honda PGM Tester or the HDS, activate A/C CLUTCH in the INSPECTION menu. If a clicking noise is heard, go to appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. If a clicking noise is not heard, go to next step.
- Turn ignition off. Disconnect PCM harness connector B. See Figure . Turn ignition on. With a fused jumper wire, momentarily connect PCM harness connector terminal B11 to ground several times. If a clicking noise is heard, update the PCM if it does not have the latest software. Substitute known-good PCM then recheck. If symptom or indication goes away, replace original PCM. If a clicking noise is not heard, check for poor connections or loose terminals at A/C clutch relay and PCM. If they are OK, check the A/C clutch relay and go to appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
RENDER: 1.0x
NO RELATED
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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.