Originally Posted by wave1957
I have a '57 Chevy truck with a TBI engine. I am going to install A/C in this truck, but the TBI harness I am currently using ('89 Chevy) came from a vehicle without A/C and does not have the wire to connect the compressor to the computer (to tell the computer to raise the idle speed when the A/C is on).
Is it OK to use A/C without this wire, or should I swap harness? Will using the A/C without this wire make the engine run rough, or even die when idling?
That wire is so the computer can keep the engine at a steady idle RPM whether the A/C is powered up or not. The drop in RPM will make the fuel metering unsteady as that is one of the fundmental measures that TBI uses for fuel metering.