On returning from vacation Sunday, I found my Wesco electric furnace fan running continuously, heat off, even with the thermostat set below room and outdoor temperature. Since we didn't need heat, I shut off the breakers. Turned the breakers back on, fan not running but a buzz from the furnace, so I thought maybe the motor had bad brushes or something like that. Shut off breakers again.
I'd been meaning to have the furnace checked anyway, so called service company. Their guy came and checked the furnace for function. He felt it was operating normally, with all the elements drawing about 19 amps. The buzzing was gone, so he assumed it was just a relay that had been briefly acting up. He didn't pay much attention to the thermostat, but I think the fan shut off a few minutes after he turned the set temperature back down.
The next day, the fan ran all day again, and nothing I do to the thermostat settings affects this. Can/should I replace the thermostat with whatever programmable unit the local Lowes has in stock? The system is 29 years old.