88 Idle Air Control Valve Troubleshooting

[rr66]

Have cleaned the IACV on 1988 dual port 1.5liter fuel injection engine. when i turn on the lights or AC, the idle speed is lowered. if i turn the key to ON, there is 10 -12 volts at the top of the 2 wires. no voltage at the bottom wire. have read that both wires are hot wires.
have started engine, and turned on AC. same results. voltage at the top wire, no voltage on the bottom wire.
does any place on the internet show the wiring diagram?
if the wiring is OK (wiring has never been messed with), does that mean that the computer is bad. No computer codes are shown. (Check engine light is NOT on). What else could it be ?? (Are both of the wires at the IACV hot wires). ??

[1990civicdxhb]

get a new battery,it happens to my car,both motors,its just using energy from the battery,it should happen when you hit the headlights too,you could just go ahead & take off the AC,less weight & no low idle! its normal

[rr66]

thanxs for the reply, but i am skeptical. a friend of mine had the car about 4 years ago, and he said that it also did that back when he had it. i have replaced the battery a couple of years ago. i had bad vacuum hoses that also contributed to idling problems until i replaced all the vacuum hoses a couple of months ago. but taking more juice from the battery would not explain the zero (0) reading at the lower wire in the connector.
And i did mention in my first paragraph that the idle speed drops off (a little) when i turn the headlights on.
If the AC did not work, then i would consider removing it. but i live in austin, texas; and the AC is very much needed here.