Pontiac Repair: 92 Firebird Engine light corresponds to cooling fan/rough idle, voltage spike, compressor cycles

Question
Hi Todd, you tried to help me back on 10/23 with this issue. I have noticed that when the cooling fan comes on the engine light comes on and the rough idle begins. To the point the car will die if I am not right there. When the fan cuts off, the light goes out and idle smooths right out. This is the 92 Firebird 3.1V6. None of the auto stores in my area carry a reader to extract code. Thanks for your help.

Answer
Hi scott. there are 2 things that could be happening here you could have a bad coil in the a/c compressor and for some reason when the compressor cycles the voltage spike is causing the light to come on. Or the extra load from the a/c being on is cuaing the isle to run lod and for some reason it'as cuaing the code. it could be ideling so low it's setting MAP codes or maybe you have an idle control motor that is slow to respond to the command for an increased idle speed. You may want to try cleaning the throttle plate and the idle control motor if they are crboned up that could be part of your isue.