rear a/c switch almost melted

Hi, I just got my new 2000 gmc safari sle 89k so far so good but one day (1 week after I got it) I smelled burnt wires and smoke coming fron the dash the rear a/c switch was melting Is this something common in these vans? if I replace the switch and wires is it comming back?
it's factory a/c everithing is stock thanks again

factory rear air? or a conversion van? look for high amp draw or more likely a bad connection at the switch--better replace the wiring connectors as well......