Why does it do this? It idles normally when the A/C isn't on. Then I turn on the A/C and after about 20 minutes, if I stop or slow down at all, it will just die!
Wow. I am not sure. I would think that maybe the belts are too tight or something and activating the AC tightens the belts to the point of killing the motor.......
Ask a dealer about it.
For small engines, the A/C is a significant load. I don't know your car, but usually, the A/C is controlled by the car's engine management system, when the clutch engages, the management system increases the idle RPM to compensate. Sound like something is going wrong in the transition. Get it diagnosed.
There are to many different things to check for me to send you on a wild goose chase. The dealer will charge you one hour to find the problem. And if you let them fix it they write that hour off of your bill.
