I have a coleman furnace/AC model EB20B. The blower motor will not shut off no matter what I do at the thermostat. Everything works fine, no icing problems, just won't shut off. The unit is all electric. I have to shut it off with the breaker.

Don't bother, many of us allow our blowrs to run 24/7. This uses only a very tiny amount of power more when compared to the traditional ON/OFF cycling. Starting a blower motor from a dead stop uses about the same power as running it continuously for 15 minutes, your home will be more comfortable too. The problem is likely a rely attached to the circuit board or the board itself. I'd have to be on site to test it but the fix is frequently left for a pro. In the meantime don't worry about the fan running, mine has run since 1988.