have a 2009 crown vic p71 the other morning i turned the defrost on to clear the windshield of fog, then turned the air conditioner on but now the heat won't shut off, the vac lines seem to work ok the door opens and close's ok but the temp **** does'nt seem to work when turned back to the blue it just keeps blowing hot air. i unpluged the wires from that switch and checked w/ volt meter nothing at all shows on the meter. i checked the fuse's under the dash they seem ok any help would be greatly appreciated. thank you