A/C Idle Boost Solenoid Valve

1987 Prelude
1. Connect system checker harness between ECU and wire harness connector.
2. Start engine and turn A/C switch to On position, then ensure compressor and condenser cooling fan operate.
3. Measure voltage between system checker harness terminals B1 (blue/yellow (+)) and A18 (black/red (-). There should be 0-1.5 volts available.
4. If voltage is greater than 9 volts, replace ECU.
5. If there is no voltage, proceed as follows:
a. Check for open circuit in black/yellow wire between regulator fuse (10 amp) and A/C idle boost solenoid valve.
b. Check for open circuit in green wire between A/T idle control solenoid valve and ECU.
c. Check for open circuit in A/C idle boost solenoid valve.