Comfortmaker furnace problem. Model# NTVM125KNB2 Initially, the blower would run constantly whether in cool,heat or off mode, Auto fan or manual-blower ran 24/7. I changed the batteries in the tstat, powered the unit down at the breaker, cleaned the filter, reassembled the stat, turned on the breaker and now the blower NEVER runs. Called the t'stat people and pretty much eliminated the stat as the problem. Opened the furnace, no damage to PC control board, fuse is good, all wires intact, good contact. Fan is not locked. When I hit the safety switch on the door, I can hear a relay click closed but nothing happens. Any ideas?

Could be there blower relay on the circuit board has become defective.
Have you checked the motor and capacitor?