Idle Up for A/C Compressor

I finally got my A/C working last week. Cold air is nice.

The only problem with the A/C now is the idle up isn't working when the compressor kicks in. Do you guys know if there is a common cause for this on these trucks? I haven't dug into it yet.

There is a bank of switches along the passenger fenderwell, one of which controls the idle up funtion.

It is a solenoid tied to manifold vacuum as its source, and when activated, vacuum pulls a dashpot located behind the carburetor. The dashpot cannot be adjusted, but the carb has a speed adjustment screw which is kind of hard to see. You have to be careful with this, as it is really easy to turn the choke idle speed screw by inadvertance. They are close to each other.

If you or someone else ever pulled the carb off the manifold, there is a chance that the arm from the dashpot was not put back into the receiver when the carb was put back on.

The easiest way to check for dashpot operation is with a vacuum pump. It either works or it doesn't. They do go bad occasionally.

I'm sorry I didn't see your reply earlier. I didn't get an email notification for it.

Soon after posting this, the 2.6L blew a head gasket or something. I had planned on putting a 302 in it anyway, so that was a good excuse to start the upgrade. Right now, the A/C is the least of my worries. our reply earlier. I didn't get a notification email.

Thanks for the response. I'll dig into it soon after fabbing a bracket for the B2600 compressor or reinstalling the 302 compressor.