A/C Signal Circuit Troubleshooting

Turn the ignition switch ON (II).
Momentarily connect ECM/PCM connector terminals A24 and E18 with a jumper wire several times.

Fig 1: Connecting ECM/PCM Connector Terminals A24 & E18
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there a clicking noise from the A/C compressor clutch?
1. YES - Go to step 3.
2. NO - Go to step 6.
Start the engine.
Turn the blower switch ON.
Turn the A/C switch ON.
Does the A/C operate?
1. YES - The air conditioning signal is OK.
2. NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
Momentarily connect under-hood fuse/relay box 14P connector terminal No. 10 to body ground with a jumper wire several times.

Fig 2: Connecting Under-Hood Fuse/Relay Box 14-Pin Connector Terminal No. 10 To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there clicking noise from the A/C compressor clutch?
1. YES - Repair open in the wire between the ECM/PCM (E18) and the A/C clutch relay.
2. NO - Check the A/C system for other symptoms.