Blower not working for heat

Hi all, I have a Carrier furnace model 58SSB with a blower control board HH84AA009. I replaced the blower motor at the beginning of summer with a unit I purchased from Grainger. The replacement went fine and the blower worked great through out the summer. Now that we have switched to heat the furnace fires up fine but with the thermostat on "auto" the blower never comes on. If I shut everything down and wait a bit I can switch the blower to "On" and it comes on. Then I can turn the heat back on and everything is fine with the exception that the blower continues to run even after the heat cycles off. Do you think I hooked something up wrong when I swapped the blower motors? I'm pretty handy with a volt meter but I'm not sure where to start testing. Thanks! Chuck