heat pump-WTF? again... WTF???

[supermanotorious]

I haven't had the a/c on in a few days since the AZ weather has been amazing, esp at night. My fan was set to "auto" and the heat pump / a.c was set to "off" (neither cold or heat). Took the kids to the fair this afternoon. Came home, opened the front door and was blasted by a gust of hot air. I was really confused but noticed the fan was blowing hot *** air out of the registers. Indoor temp= 105.5 F..... I checked the thermostat and everything was turned off. I had to run outside and kill the breaker. Would any of you know why the heater went rogue?

 

[itsid]

thermostat shorted out and activated a heat cycle for some unknown reason
-age for example-
older thermostats come with bimetal temp switch, that you only set the threshold for (original distance between the contacts) those can fuse over the years and practically weld shut.

or a switch failed on you.. set to off, but actually in "on"-position *shrugs*

'sid