pioneer avic n1, ac stopped working

What kind of vehicle?   Check for a short behind hu, I bought a 1992 eclipse from a guy with an aftermarket stereo already installed by himself,  had it for about 4 months when things started to go wrong.  Car died suddenly, would start back up and run fine for a ehile and do it again, turn signals weren't working, high beams were inverted (high beams were low beams and visa versa) dash lights, dome lights.  Took it in to shop to find out my cars computer was fried.  Fixed that but still had lighting issues, changed out my deck and found tucked in the back, the factory deck illumination wire bare and ground out to the chassis.  Eventually the car died again and when i ripped out the cars wiring harness i found it melted into one big mess throught the entire car.  Sorry that was long but i'm still upset about it.  My point is a fuse won't always blow with a short, and it can cause all kinds of wierd stuff.

Do you drive a gm truck? It is very easy to burn up the circuit board that is directly below the radio.