Started my truck this morning let it warm up like everyday while I scraped off the snow. Had the defroster going on the way to work. Been at work for a few hours and went out to my truck to grab something and the heater is just going full blast. Turned the ignition on and off and it just keeps going. Shuts off when I switch it to off but I can turn it back on with no key in the truck. Nothing else turns on just the heater and AC. Any ideas? Thanks!