A/C Problem - Very High Idle

[rrhodes]

Hi,

The a/c in my 89 works VERY well - I'm please because it's very hot right now. The problem is this:

I was running the a/c earlier in July when it was not as hot and my idle was fine - when the a/c compressor kicked in the idle boost brings up the idle like it should. Now that it's really hot though, the idle will go up to 2500-3000 and then stick there. I can hear a click under the dash and then the idle goes way up.

Just to make sure this was only happening when I use the a/c I just drove down the highway for about 45 minutes without the a/c on and when I stopped the idle was fine.

So the problem happens when the a/c is in use - any ideas??

Many thanks,
Rob

[russiankid]

Sounds like the A/C idle boost diaphragm is opening the throttle plate way to much. I would check the adjustment on it.

[rrhodes]

Thanks for the feedback. I was thinking about that adjustment as well but the odd thing is that sometimes the idle is fine with the a/c on and then other times it out to lunch. I would think that if the idle adjust is out of whack it would be out all the time - what do you think?

[russiankid]

The diaphragm could be wearing out. I had a diaphragm wear out and it would sometimes work properly or completely raise the idle way to high. This wasn't for the A/C but it decelerated the throttle plate.

[greentee76]

Also make sure the lever that the A/c boost solenoid pushes against on the carb(I'm assuming you're carbed?) is tight. If that lever is loose it could cause the idle boost to act wierd.