1978 throttle solenoid does not engage when compressor kicks on

[Charlie P.]

The solenoid itself is working. It appears that the circuit from the compressor is not direct to the solenoid, going through a pressure sensor and some other switching maybe. (obviously I am not well-versed in A/C systems). Compressor cycles and system is producing cold air.
What is the likely culprit?

Thanks,
Charlie

[Edward J.]

Re: 1978 throttle solenoid does not engage when compressor kicks on

Charlie have you checked for power at the solenoid connector when the a/c is engaged? sometimes the solenoid will not over power the carb. return spring and may require tap of the throttle. Another thing that sometimes happens is someone was using the solenoid to adjust the idle, which will result in the solenoid being turned in to far and make it look as it not working.

[Charlie P.]

Re: 1978 throttle solenoid does not engage when compressor kicks on

Ed, I didn't check for power to solenoid when compressor kicks on, but I will do that. Since the bench test was good, I am assuming voltage is not going to the solenoid, but will confirm. The plunger is adjusted such that it will open the throttle more when the solenoid is energized.

Thanks,
Charlie