I have a split Heat/AC. AC appears to be external to the home and is on its own CB.

Heat is installed in the attic.

This afternoon, my son discovered that the blower motor in the attic was still running even though the heat was turned off at the thermostat.

The thermostat is a six wire, Select Comfort model. My son, removed the batteries from the thermostat fan motor still ran. Then he removed the slow-blow fuse for the thermostat and the blower still kept running.

Finally, he went to the main panel and shut the A/C breaker down. Blower motor still ran. Then killed the Heat breaker which finally shut the motor down. When he reset the breaker, the motor did not restart.

Since the motor did not shut down until the power was cut, is telling me that the failure may be in a controller board within the heat plant.

Please, I am open to any and almost all reasonable solutions.

Is this a gas furnace or a electric furnace?

Josh,

It is an electric furnace, mounted in the attic.

Sounds like you may need a new heat sequencer.

http://www.drillspot.com/pimages/408/40804_300.jpg

Josh,

I am a reasonably skilled tech with a very strong background in electromechanical devices.

Assuming I can get to the attic device (I understand that there are two of them up there) where would I start looking for the heat sequencer?

How big of Chinese Fire Drill is it to swap one out?

Obviously, I will need the correct model number to get the correct heat sequencer, but do you favor one model line over another?

Donf, there will be a removable panel which houses all the electrical components. On the door of the furnace there very may well be a schematic. If you post the MFG and the model number, one of us will be able to help you more thoroughly. A heat sequencer is basically a relay or contactor. If the fan continues to run after the control circuit is broken, it's probably sticking. No attempts should be made by you to repair this until you turn off all the power. Next time it happens, try cycling the fan switch on the thermostat.