Whats up guys, i have a pretty smooth idle just sitting there in neutral , but then the second i turn the a/c on the light constanstly bounces up and down.. like it will rev to 1800 then drop to 500, then right back up to 1800 over and over again, same wen i put the deforster button on... any ideas?

New iac already, cleaned throttle body, and cleaned maf

 

sounds like an electrical problem

 

maybe your alternator isgoing out go to your autoparts store and have it tested its free...

 

The air conditioner and defroster both use the air conditioner compressor. Maybe your compressor is on it's way out and when it is in use, it is putting a strain on the entire system either via electronics or via the serpentine belt. Just a guess.

Good luck!

 

ill go get it tested and see what happens

 

lol first thing that popped in my head was the rear defroster

 

Got to be alternator or the battery is goin out.

 

I don't have a rear defroster... that thought never even entered my head! If, in fact, it is the rear defroster that the OP was talking about, then I would lean more towards a electrical problem then a compressor problem. Kragen will hook it up and test it for free.

Good luck!