Hi all.

I recently acquired my first Caddy :thumbsup: and it's a '67 Eldorado. It runs great, everything works and it only has 60k miles on it.
I have a small problem with the A/C, when the engine has run awhile and it's idle, the engine revs up and stays there until I switch the A/C off, then it idles down. Anyone got an idea what causes this?

Your "idle kicker" is misadjusted.

Back before EFI, they put a small electric solenoid on the carb to increase the idle speed when the AC was turned on. Otherwise the extra load from the AC would stall the motor nless you kept the idle turned up too high all the time.

I'm pretty sure the AC is 'locked out' untill the engine is warmed up slightly when you have the automatic climate controll on and that is why the delay.

If you take the aircleaner off, and look on the drivers side where the throttle linkage hooks to the carb, you should see a cylindrical device with a single wire going to it. When the AC is on and the engine warmed up, this would extend and increase the idle speed.

Take two wrenches and loosen the two nuts that adjust where the idle kicker is. You'll want a low RPM tach of some sort to monitor engine RPM's as well. Then, with the engine up to temp adjust the kicker so it only bumps the engine up to 800 rpm or so when the AC comes on and tighten those nuts back down.