What is this?

[Algershick]

I'm trying to diagnose a heater issue, and I noticed this little thing while tracing wires. Its mounted to a factory bracket on the drivers side of the intake manifold, and the wiring loom appears to come from the AC compressor/HVAC stuff. What is it?

 

[xitabl442]

fast idle solenoid?

lots of wiring diagrams here: http://www.maliburacing.com/wiring.html

 

[Algershick]

Thanks for the response! Wouldn't a fast idle be similar to an IAC? This is a '78 301, non computer controlled. I'm curious now, I want to say I remember seeing one of these on a 3rd gen Trans Am I used to have.

 

[xitabl442]

I am not very familiar with those motors, I just saw it on the diagram. After I looked at your pic again, I think the fast idle might be bolted to the left front of the carb. Is that part on the throttle linkage? Any hoses attached with it?

 

[Algershick]

There aren't any hoses attached, it's just wiring. The black round part is a button that can be depressed. It's attached to a factory appearing bracket.

 

[oldsmobile joe]

it looks like a wide open throttle a/c cut out switch. does the plunger get depressed when the throttle is moved to wide open throttle? this turns off the a/c during wide open throttle to give you more power. if you trace the dark green wires in the picture, it looks like they go over to the a/c comp.
your fast idle is controlled with steps on the choke lineage on the passenger side of the carb. the round cylinder in front of the throttle linkage on the drivers side of the carb, is the a/c idle up solenoid. with a/c on, the light green wire activates this solenoid and it bumps up the idle by moving the throttle linkage. which prevents the engine from stalling or running too slow at idle.

 

[Algershick]

Thank you for your response and explanation.