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HOMESERVICE MANUALSACURA20043.5RLREPAIR AND DIAGNOSIS (SINGLE PAGE)HEATING, VENTILATION & A/C (HVAC)HVAC CONTROL SYSTEMSAUTOMATIC A/C-HEATER SYSTEMSTROUBLE SHOOTINGA/C SYSTEM DOES NOT OPERATE
2004 Acura 3.5RL

A/C System Does Not Operate

2004 Acura 3.5RLSECTION A/C System Does Not Operate
  1. Check fuse No. 3 (7.5-amp) in underdash fuse block. Replace fuse if blown. If necessary, repair short(s) to ground. If fuse is okay, go to next step.
  2. Disconnect fan control unit 12-pin harness connector. Turn ignition on. Check for voltage between ground and terminal No. 7 (Black/Yellow wire) of fan control unit 12-pin harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between fuse No. 3 (7.5-amp) and fan control unit.
  3. Turn ignition off. Check for continuity between ground and terminal No. 3 (Black wire) of fan control unit. If continuity exists, go to next step. If continuity does not exist, check for open Black wire between fan control unit and ground (located at passenger's kick panel). If wire is okay, check for poor ground connection.
  4. Reconnect fan control unit harness connector. Disconnect A/C pressure switch 4-pin harness connector. Turn ignition on. Measure voltage between ground and terminal No. 4 (Red/White wire) of A/C pressure switch 4-pin harness connector. If battery voltage exists, go to step  7. If battery voltage does not exist, go to next step.
  5. Measure voltage between ground and terminal No. 4 (Red/White wire) of A/C pressure switch 4-pin harness connector with fan control unit 12-pin harness connector connected. If battery voltage exists, repair open in Red/White wire between A/C pressure switch and fan control unit. If battery voltage does not exist, go to next step.
  6. Check for loose wires or poor connections at fan control unit 12-pin harness connector. If connections are okay, substitute known-good fan control unit and recheck. If symptom does not exist after substituting known-good fan control unit, replace original fan control unit.
  7. Turn ignition off. Check for continuity between terminal No. 1 (Yellow/Black wire) and No. 4 (Red/White wire) of A/C pressure switch. If continuity exists, go to step  9. If continuity does not exist, go to next step.
  8. Check A/C system pressure. See A/C SYSTEM PERFORMANCE  under SYSTEM TESTS. If A/C system pressure is not within specifications, repair refrigerant portion of A/C system. If A/C system pressure is okay, replace A/C pressure switch and go to next step.
  9. Reconnect A/C pressure switch 4-pin harness connector. Remove climate control unit, and disconnect 8-pin and 20-pin harness connectors. See CLIMATE CONTROL UNIT  under REMOVAL & INSTALLATION. Turn ignition on. Check for battery voltage between ground and terminal No. 12 (Yellow/Black wire) of climate control unit 20-pin harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Yellow/Black wire between A/C pressure switch and climate control unit.
  10. Measure voltage between ground and terminal No. 1 (Black/Yellow wire) of climate control unit 8-pin harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between climate control unit and fuse No. 3 (7.5-amp).
  11. Turn ignition off. Check for continuity between ground and terminal No. 7 (Black wire) of climate control unit 8-pin harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire between climate control unit and ground (located at passenger's kick panel). If wire is okay, check for poor ground.
  12. Check for loose wires or poor connections at climate control unit 8-pin and 20-pin harness connectors. If connections are okay, substitute known-good climate control unit and recheck. If symptom does not exist after substituting known-good climate control unit, replace original climate control unit. See CLIMATE CONTROL UNIT  under REMOVAL & INSTALLATION.
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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.