My rig shakes/vibrates when the a/c is on. I also noticed that the idle speed is about 800 rpms when the a/c is on and about 700 when it's off. I can definitely feel the truck shaking everytime the a/c is turned on. I was thinking about making some adjustment on the IAC but I don't know where it is and if this is a good option. Pics of it will be a great help. Thanks.

George

 

Isn't it normal for the AC to drive the engine a bit harder at idle? I think pretty much every vehicle I've owned has done this. Can't remember if they idle much higher when its on tho.

 

With regards to my original post, is the little bolt the adjustment for idle?




Thanks.

George

 

Yep, that looks like the idle stop. But that isn't your problem.

There is a solenoid which idles the engine higher to compensate for the air conditioner load, it's entirely separate from the idle stop screw. All vehicles do this, although on many newer engines it's getting more common for this to be an entirely electronic function (in the computer) rather than mechanical (solenoid.)

Question is - why would it shake/vibrate? No reason why idling up another 100 rpm or so would do that. Check the basics - your pulleys and belts, etc. first.

 

I played around with the idle stop but it didn't seem to do any change wrt my idle speed. I'm really baffled why it's doing this. I haven't driven the rig often lately but I definitely noticed the vibs as soon as I turned the a/c on. That idle stop goes to a little vacuum port I believe but I'm not sure. Adjusting it in or out didn't change my idle speed at all. Other than the vibs, everything rans smooth though I'm thinking about changing the belts pretty soon. I currently have 70k miles on the odo.

George