Thanks. First thing to note is that when the thermostat is on, whether it be heating or cooling, everything works fine. Cycles run as normal, with no problems. Then, out of nowhere, at no particular time of day, when the thermostat is off, or even disconnected, I'll hear the fan kick in. The inducer motor and fan motor will both be running (no gas or ignition). Then, after awhile, the inducer motor will go off, and the blower soon after. Sometimes, the inducer motor will go on and off a couple of times while the blower motor is still running. I'm usually pretty handy, but this has me stumped. I was hoping someone a lot smarter than me would nail this! I'll inspect the board today, but if nothing is obvious, I'll have to bite the bullet and call someone.