A/C Signal Circuit Troubleshooting

WARNING: This page is about a different car, the 2009 Honda S2000, 2008 Honda S2000, 2007 Honda S2000, and 2006 Honda S2000. 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.
Is it ON?
1. YES - Go to step 5.
2. NO - Go to the A/C pressure switch circuit troubleshooting (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 A/C SYSTEM INSPECTION .
2. NO - Go to step 9.
Momentarily connect under-hood fuse/relay box 16P connector terminal No. 11 to body ground with a jumper wire several times.
Is there clicking noise from the A/C compressor clutch?
1. YES - Repair open in the wire between the ECM (E18) and the A/C clutch relay.
2. NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM (see UPDATING THE ECM ), then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM (see ECM REPLACEMENT ).
  
  Fig 1: Connecting Under-Hood Fuse/Relay Box 16P Connector Terminal No. 11 To Body Ground With Jumper Wire
  Courtesy of AMERICAN HONDA MOTOR CO., INC.