Whenever i switch off my defroster i hear noise like a spring going "boing" coming from underneath the passenger side dash. my defroster still works but barely, it only melts about 6in worth of space on the rear window, towards the top. theres a small piece on top and a large section on the bottom that dont get defrosted. what is under the passenger side dash that controls the defroster?

 

I belive the relay for the rear defroster is over there on the firebirds