Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSACURA19983.5RL SPECIAL EDITIONREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM/COMPONENT TESTSIDLE CONTROL SYSTEMAIR CONDITIONING SIGNAL2.5TL
1998 Acura 3.5RL Special Edition
Air Conditioning Signal: 2.5TL
1998 Acura 3.5RL Special EditionSECTION 2.5TL
- Turn ignition off. Disconnect A/C pressure switch connector located at left front of engine compartment, next to receiver dryer. Turn ignition on. Backprobing, measure voltage between PCM 26-pin connector terminal No. 26 (Brown/Black wire) and PCM 16-pin connector terminal No. 3 (Blue/Black wire). See Figure. If battery voltage exists, go to step 3). If battery voltage does not exist, go to next step.
- Turn ignition off. Disconnect PCM 16-pin connector. Check continuity between ground and PCM 16-pin harness connector terminal No. 3 (Blue/Black wire). See Figure. If continuity exists, repair short in Blue/Black wire between PCM 16-pin connector and A/C pressure switch. If continuity does not exist, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM. Ensure A/C is operating properly. See A/C-HEATER SYSTEM article in AIR CONDITIONING & HEAT section.
- Turn ignition off. Reconnect A/C pressure switch. Turn ignition on. Using a jumper wire, backprobing, momentarily connect PCM 26-pin connector terminals No. 8 (Red/Blue wire) and No. 26 (Brown/Black wire), several times. See Figure. If A/C compressor clutch clicks, go to step 5). If A/C clutch does not click, go to next step.
- Locate A/C clutch relay in left rear corner of engine compartment. Using a jumper wire, backprobing, connect A/C clutch relay connector terminal No. 2 (Red/Blue wire) to ground, several times. If A/C clutch clicks, repair open in Red/Blue wire between PCM 26-pin connector and A/C clutch relay. If A/C clutch does not click, other A/C problems exist. See A/C-HEATER SYSTEM article in AIR CONDITIONING & HEAT section.
- Start engine. Turn blower and A/C switches on. If A/C operates, A/C signal is okay. If A/C does not operate, measure voltage between PCM 26-pin connector terminal No. 26 (Brown/Black wire) and 16-pin connector terminal No. 3 (Blue/Black wire). See Figure.
- If voltage is not less than one volt, repair open in Blue/Black wire between PCM 16-pin connector and A/C switch. If voltage is less than one volt, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM. Ensure A/C is operating properly. See A/C-HEATER SYSTEM article in AIR CONDITIONING & HEAT section.
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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.