A/C idle is rough

[jeremy5780]

Jeepin in FL I need A/C so don't knock me. My CJ7 with the AMC 258 i6 / 4.2l idles smooth with the A/C off right around 750-800 RPM but when you kick the A/C on it drops to around 650-700 RPM and idles rough. Anybody else experiencing this issue and if so is there a way to correct it like a high idle boost when under load??

 

[Torxhead]

There is a Sole-vac throttle positioner located on the upper drivers side of the carb. It controls the idle speed by electrical and vacuum thru the computer. It could be just out of adjustment or it could be shot and needs replacement. Also there is a vacuum solenoid that controls it. This complete webpage along with this page from it may help you out:Sol-Vac

 

[Lumpy Grits]

Your sol-vac is there to kick the idle speed up. It's triggered by vacuum or electric input.
Sol-Vac

FWIW; When I set an idle speed on a manual tranny. I set it under full electrical load. Lights on, blower motor on, wipers on etc.
Auto-Same deal and in gear.
LG

 

[Posi]

I'm assuming you have an auto Transmission or the your CJ originally came with one. You should have a solenoid to raise the idle when you switch on the AC.
Check to see if you have power to it, and that it's functioning properly.

 

[jeremy5780]

Manual Transmission . Also I have the motor craft 2100 carb and do not have this sol-vac you all speak of.

 

[Lumpy Grits]

Manual Transmission . Also I have the motor craft 2100 carb and do not have this sol-vac you all speak of.

Never did you say what carb you are run'n, until now....
THAT is the WHY, it is always a good idea to fill out your vehicle information.
So WE don't have to guess.....

Set your idle with the electrical system under full load.

EDIT- The carb info is in the OP's info under 'about me'.

LG

 

[CJ]

I would hit a scrap yard and look for any Ford or AMC with a Motorcraft carb and A/C. You should be able to grab an idle stop solenoid and bracket for cheap.
An alternative is buy some thing like -->> Duralast Idle Stop Solenoid E407



for $12 and make or modify the bracket. The solenoid needs to be wired into the A/C clutch circuit.

 

[jeremy5780]

under mods in my profile I have listed all of my upgrades and modifications done to my jeep. Don't scold me for lack of info, feel stupid for not checking!

 

[jeremy5780]

Thanks cj!

 

[CJ]

Found a pic of a stock 2100 with an idle stop --

 

[Lumpy Grits]

under mods in my profile I have listed all of my upgrades and modifications done to my jeep. Don't scold me for lack of info, feel stupid for not checking!

You are CORRECT. I did not look under 'about me' in your profile.
I DO APOLOGIZE FOR THAT!
I only clicked on your name-
STILL-If you have said in your first post what carb. It would not have misled other posters as well.
The OEM carb for that jeep is a Carter BBD.
BTW-You left out what tranny you're run'n.
LG

 

[jeremy5780]

I apologize as well your only helping me out. Rough day, but no excuse. Thanks everyone for your help. I rely heavily on this site for all my cj problems.

 

[Lumpy Grits]

I apologize as well your only helping me out. Rough day, but no excuse. Thanks everyone for your help. I rely heavily on this site for all my cj problems.

NP
We ALL hav'em......


Knowing well of the 2100's history of vacuum leak issues. I would suggest you do your best to eliminate that as any possible issue.
With the warmed up engine running at idle-spray VERY soapy water all around the carbs base. If there's a leak. You will see the bubbles suck'd inside and hear a pitch change in the engine.
Also-Make sure all of the manifold bolts are still 'tite'.
LG

 

[Posi]

The A/C clutch circuit has a brown 16g wire

 

[djnineball]

fwiw check your grounds. i used to drive a dodge neon for work and my idle would dip severely when i put the ac on. i am also an audiophile so my system typically puts a draw on my car, and upgrading the big 3 (grounds) is always step one. i did it in my neon and the drop went away. grounds are very important.

 

[Hedgehog]

Jeremy - Lumpy is right in that it is best for all involved to have your jeep information show in the profile under your name. If I were you I'd open my profile and copy and paste your CJ information to where it will show up automatically. We get quite a few new guys (not that you are a new guy) who don't know that how helpful this is for all involved. I've given similar advice. I'm sure in Lumpy's case it was meant as advice not a scolding (not that Lumpy needs my intervention in this situation ).

 

[79cvx20]

Did you find a solenoid to fit the 2100 carburetor?

 

[Lumpy Grits]

You do know this is a 4 1/2 year old thread....
LG