A/C Signal Circuit Troubleshooting

WARNING: This page is about a different car, the 2006 Acura MDX, 2005 Acura MDX, 2004 Acura MDX, and 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

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.
Does it indicate ON?
1. YES - Go to step 5.
2. NO - Go to the A/C pressure switch test (see A/C PRESSURE SWITCH CIRCUIT TROUBLESHOOTING .
Check the A/C system.
Does the A/C system operate?
1. YES - The air conditioning system circuit is OK.
2. 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?
1. YES - Do the A/C system test (see A/C SYSTEM TEST ).
2. NO - Go to step 9.
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect PCM connector B (56P).
Turn the ignition switch ON (II).
Momentarily connect PCM connector terminal B11 to body ground with a jumper wire several times.

Fig 1: Connecting PCM Connector Terminal B11 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there a clicking noise from the A/C compressor clutch?
1. YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING ), then recheck. If the symptom/ indication goes away with a known-good PCM, replace the original PCM (see PCM REPLACEMENT ). The air conditioning signal OK.
2. NO - Check for poor connections or loose terminals at the A/C clutch relay and the PCM. If they are OK, check for the A/C clutch relay (see POWER RELAY TEST ), and other A/C systems.