check engine light comes on only when a/c is on

I have a 2000 GP GT, the engine light comes on every time I turn on the a/c. It goes out is I drive it the next time with a/c off. Any ideas??

Try to scan the computer when the light is on, if you can't then scan it to see if there are any stored codes. This actually sounds like the increased load on the engine is causing a misfire condition which is causing the light to come on. If you can get a code post it here and someone will help you figure out the problem.

unfortunately I don't have a code reader, I guess I will have to take it somewhere to get it. I miss those old 90's GM cars where you could just count the number of engine light flashes to get the codes.

unfortunately I don't have a code reader, I guess I will have to take it somewhere to get it. I miss those old 90's GM cars where you could just count the number of engine light flashes to get the codes.

I hear ya there. However, all things considered, I'd rather have OBD2.

Did you know that OBD1 systems are not capable of missfire detection? Your car could be stumbling on 3 of the 6 cylinders, and it would not trip a SES light.

Bring it to advance or autozone for a free scan with your AC on.