I awoke last night to hear the fan running in the attic. When I checked the thermostat it was set to off. I turned on the A/C and then shut it off thinking it would shut the fan down also but it just shut off and the fan kept running even with thermostat in the off position. I finally had to switch off the breaker to get it to go off. When I turn on the breaker it does the same thing. I climbed up into the attic to see if maybe a rodent got up there and was chewing on wires but everything looked clean and fine. I had a problem with my main breaker a couple weeks back and had it replaced because it was only maintaing 40 v not 120v( Old 1959 panel) to some of the outlets. I checked and have 120 everywhere. Could my thermostat have been damaged by the low voltage? Or is the unit itself in the attic broken even though it has the proper voltage? Any ideas?