My wife had our ac set on 78, well it has gotten pretty cold here lately so today while I was gone she turned the heat on. Now 6 hours later I had to turn off the power for it on the breaker to get the heat to turn off. The furnace was set on 73, but when I got home the thermostat was sitting at 90 and my wife was freaking out. I tried changing the unit to off, but it kept blowing, I also tried turning it down, but that didn't work either. My only option was to turn it off by the breaker. I was wondering if anyone knew what to do??