1999 Acura 2.3CL AutomaticFACTORY OEM SERVICE PROCEDURE

Air Conditioning Signal: 3.2TL

  1. Turn ignition off. Disconnect A/C pressure switch connector. Turn ignition on. Backprobing, measure voltage between PCM 32-pin connector terminal No. 27 (Blue/Red wire) and PCM 25-pin connector terminal No. 20 (Brown/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, go to step  3.
  2. Turn ignition off. Reconnect A/C pressure switch connector. Turn ignition on. Momentarily connect jumper wire several times between PCM 32-pin connector terminal No. 17 (Red wire) and PCM 25-pin connector terminal No. 20 (Brown/Black wire). If A/C compressor clutch does not make a clicking noise, go to step  4. If A/C compressor clutch makes a clicking noise, start engine. Turn blower switch and A/C on. If A/C operates, A/C signal is okay. If A/C does not operate, go to step  5.
  3. Turn ignition off. Disconnect PCM 32-pin connector. Measure continuity between ground and PCM 32-pin connector terminal No. 27 (Blue/Red wire). If continuity is present, repair short circuit in Blue/Red wire between PCM 32-pin connector terminal No. 27 and A/C pressure switch. If continuity is not present, replace PCM. If symptom or indication goes away, replace original PCM. Ensure A/C is operating properly. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  4. Momentarily connect jumper wire several times between underhood fuse/relay box 16-pin connector terminal No. 11 (Red wire) and ground. If A/C compressor clutch makes a clicking noise, repair open circuit in Red wire between PCM 32-pin connector terminal No. 17 and A/C clutch relay. If A/C compressor does not make a clicking noise, problem is with A/C system. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  5. Measure voltage between PCM 32-pin connector terminal No. 27 (Blue/Red wire) and PCM 25-pin connector terminal No. 20 (Brown/Black wire). If less than one volt is present, replace PCM. If one volt or more is present, repair open circuit in Blue/Red wire between PCM 32-pin connector terminal No. 27 and A/C pressure switch.
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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.

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