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 Signal Circuit Troubleshooting
- Start the engine.
- Turn the blower switch on.
- Turn the A/C switch on.
- Check the A/C CLUTCH in the DATA LIST with the HDS.
Is it ON?
YES - Go to step 5.
NO - Go to the A/C pressure switch circuit troubleshooting (see DTC B2979 OR PRE SENSOR OPEN IS INDICATED: AN OPEN IN THE A/C PRESSURE SENSOR CIRCUIT ).
- Check the A/C system.
Does the A/C system operate?
YES - The air conditioning system circuit is OK.
NO - Go to step 6.
- Turn the ignition switch OFF.
- Turn the ignition switch ON (II).
- Activate the A/C CLUTCH in the INSPECTION MENU with the HDS.
Is there a clicking noise from the A/C compressor clutch?
YES - Do the A/C system test (see A/C SYSTEM TEST ).
NO - Go to step 9.
- Momentarily connect under-hood fuse/relay box 16P connector terminal No. 15 to body ground with a jumper wire several times.Fig 1: Connecting Under-Hood Fuse/Relay Box 16P Connector Terminal No. 15 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there clicking noise from the A/C compressor clutch?
YES - Repair open in the wire between the PCM (E27) and the A/C clutch relay.
NO - Update the PCM if it does not have the latest software (see UPDATING THE PCM ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM (see SUBSTITUTING THE PCM ).
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.