1973 Idle Stop Solenoid

[Thomas R.]

The Idle Stop Solenoid energizes in all wheel positions except off on the control. I think when in the heat position the solenoid should be de-energized? Can you confirm?

Disconnected control unit plugs but still energizes, is their a relay in the circuit? Have checked wiring schematic but did not find one.

Your thoughts!

[Patrick H.]

Re: 1973 Idle Stop Solenoid

The idle stop solenoid is on the carburetor, yet it seems you're talking about heater controls in the rest of the question...?

[Thomas R.]

Re: 1973 Idle Stop Solenoid

Patrick,

Thanks.

Your correct. Since the solenoid operates when the (e.g. Heat/ AC/Vent) control wheel is turned from OFF in all positions. I thought, the solenoid only works on Max A/C, A/C, Bi-Level, Defrost but did not on Vent/Heat; I am not sure about the operation. If you can confirm the operation, that would be super.

Earlier Vette systems when from off to any other selection; the solenoid would work in all positions. I hope, this helps clarify.

Tom

[Patrick H.]

Re: 1973 Idle Stop Solenoid

OK, I see what you're after.

Yes, using AC should make it turn on.
However, its not the only thing that makes it work, so it's possible that other parameters will have it working too.

[Ed D.]

Re: 1973 Idle Stop Solenoid

Unless the 73 system works differently then the 72, which I believe is the same. The solenoid is for anti dieseling and turns on when the ignition is turned on and shuts off when the ignition turns off. This occurs no matter what position the thumb wheel and works the same way with AC or no AC. The purpose of the solenoid is to close the carbs idle circuit and prevent fuel flow, to prevent engine run on and vapor escaping into the atmosphere.
Ed

[Patrick H.]

Re: 1973 Idle Stop Solenoid

Unless the 73 system works differently then the 72, which I believe is the same. The solenoid is for anti dieseling and turns on when the ignition is turned on and shuts off when the ignition turns off. This occurs no matter what position the thumb wheel and works the same way with AC or no AC. The purpose of the solenoid is to close the carbs idle circuit and prevent fuel flow, to prevent engine run on and vapor escaping into the atmosphere.
Ed

Ed,

Some of these things, especially this solenoid's function, changed yearly.
Not at home to check my manual today and get into subtleties of it.
Some years - I believe 73 - it's to support idle speed when the AC is on. In our 72s, its on all the time.

I'm sure if I'm wrong someone will let us know.

[David C.]

Re: 1973 Idle Stop Solenoid

The idle solenoid on my 73 (no AC) is energized at all times, even with the ignition switch on but not running. It maintains the idle speed, and prevents run-on as mentioned.

[Thomas R.]

Re: 1973 Idle Stop Solenoid

Ed,

Thanks, I agree with your comment.

Thanks,

Tom

[Thomas R.]

Re: 1973 Idle Stop Solenoid

Patrick,

Thanks for the feedback. This closes my thoughts. I've had the 73 since new but, just did not remember it on after starting.

appreciate yours and Ed's time.

Thanks again,

Tom

[John S.]

[Patrick H.]

Re: 1973 Idle Stop Solenoid

OK, 73 did work the same as 72 then.

FYI, the "idle screw" on the carb was then supposed to be set to ~400 rpm. When the key is turned off, the solenoid disengages and the engine quits because it's only set to 400 rpm.

My 72 idles at 400 rpm quite nicely.

[Thomas R.]

Re: 1973 Idle Stop Solenoid

John,

Thanks for taking the time to check my question out. I bought my 73 new and am going over it with the new judging book. It raised a few questions in my mind. It's great to have you folks provide information for clarification.


Thanks.

Tom

[Thomas R.]

Re: 1973 Idle Stop Solenoid

Patrick,

Thanks for idle operation info.

Tom

[Sal C.]

Re: 1973 Idle Stop Solenoid

Also known as an anti-diesel solenoid, it has nothing to do with heat or A/C settings. It drops the idle when the key is turned off. It was pretty common, however, and I've done it myself on my LT1 A/C car, to modify it so it raises the idle when the A/C compressor kicks on.

[Patrick H.]

Re: 1973 Idle Stop Solenoid

Also known as an anti-diesel solenoid, it has nothing to do with heat or A/C settings. It drops the idle when the key is turned off. It was pretty common, however, and I've done it myself on my LT1 A/C car, to modify it so it raises the idle when the A/C compressor kicks on.

I believe that in 1971 it's integrated to work with the AC system, and that's the car on which I have AC.
As we see, 72 and 73 are different, as is 70.