Heya everyone. Soo last year around this time my heater was stuck on full hot and wouldn't turn down.... well at the beginning of summer it changed to full cold. Now it wont turn to heat. I just changed the switch today because it would turn all the way around and I though that might have been it (the fan speeds and the vent control work just fine). Well the heat still doesn't come on . My car heats up and stays in temp range just fine doesn't get hot and doesn't stay cold. I think it might be the heater core but I don't know for sure. Any suggestions would be wonderful !