WARNING: This page is about a different car, the 1992 Acura Legend. However, it is still accessible from the selected car via links, so may be relevant.

Connect PGM-FI test harness between ECU and vehicle harness. Unplug connector "C" from main harness only. DO NOT disconnect from ECU. Turn ignition on.
Measure voltage between ECU terminals C3 (positive) and A26 (negative). If voltage is not about 10 volts, substitute a known good ECU and recheck voltage.
If voltage is about 10 volts, reconnect connector "C" to main wiring harness. Momentarily connect terminals A15 and A26 together and check for clicking of A/C clutch.
If A/C clutch clicks, go to next step. If A/C clutch does not click, jumper Red/Blue wire of A/C clutch relay connector to ground. If A/C clutch clicks, repair open in Red/Blue wire. If A/C clutch still does not click, repair A/C clutch circuit.
Start engine, and turn blower on. Turn A/C switch on. If A/C operates, A/C signal is okay. If A/C does not operate, measure voltage between terminals C3 (positive) and A26 (negative).
If voltage is more than one volt, repair open in Blue/Black wire between terminal C3 and cooling fan control unit. If voltage is less than one volt, substitute a known good ECU and recheck voltage.

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.

Safety Warning

Air Conditioning Signal

Use the Manual With the Right Hardware

When to See a Mechanic