Bryant 90 furnace will ignite, heat furnace, but does not kick on the blower when on AUTO. If I put it on ON position, it will run continually. There is also a smell of bruning wires coming out of the vents. The air flow is not very strong coming out of the vents, it will barely blow a piece of paper away from venst. The mail box of the furnace will heat up to almost 120 degrees, hot to touch, yet not blowing enough to heat house. I changed batteries in the thermostat and checked and tested all fuses, all wires are connected in the unit. The small fan, about 8-10" moves and the motor turns without making any noises. What could be wrong?