AC newly installed, now crazy idle??? Help.. (1 Viewer)

[RS41AB]

My truck was running great, brand new carb. I took it a step further and had the AC rebuilt. Now the AC works but my idle is crazy. Fast/Slow. The accelerator pedal actually moves up and down. Otherwise it's fine. Normal driving with the AC off is fine. Turn on the AC and all hell breaks loose. Thoughts?

 

[Crelok]

as much as i know is when you turn your a/c on,it will lower in revs (idle),and go back to your normal idle when its switched off.

jas

 

[IH8Wood]

AC increases the idle speed. There is an adjustment on the front of the carb. Idle should jump to around 1000 rpm.

 

[RS41AB]

Which one?

 

[Crelok]

i think i got it the wrong way around,(as much as i know,seems i dont no much)

soz.

 

[gsdog2]

Look at the front of the carb...you will see the diaphram pulling in and out a rod attached to a mechanism with a screw and a spring on it. Take a screwdriver and turn the screw until the pulsing stops, inwards if I recall.....it will. Then just adjust for idle (A/C on of coarse) to about 1000-1200rpm. This is called the A/C idle up screw.

 

[2mbb]

It's the ac idle up circuit. You can do a search to get more info. The above poster has it correct EXCEPT, I think you turn the screw out (counter clockwise) to reduce the idle up speed. When the ac idle up speed is set too high, it sets up an instability with the carburetor vacuum which causes the surging.

 

[RS41AB]

Great, perfect info. I'll try tomorrow after work. For what it's worth, I have the FSM for both the body/chassis (with the AC section) and the engine/fuel system (with all the carb rebuild), plus supplements, and I can't find a single section mentioning the AC idle adjustment. So, again, MUD provides great information. I'll let you all know how it goes tomorrow.

RS41AB