I though my problem had to do with the new thermostat I installed but have now realized that the thermostat is working fine. Heat is coming out of the vents however I now realized that no hot air is ever being forced out of the vents thus the house is never reaching the setpoint temperature. I have made an appt. for someone to do a pre-season tune-up on the furnace and know they will ultimately diagnose the problem. In the interim, are there any suggestions as to what I can do to definitively diagnose and/or fix the problem? Heat is coming out of the vents. I've heard the fan work and have seen the flame light. I did notice that I have 4 flashing lights which has to do with the high limit. I'm guessing the thermostat is working too hard to reach the setpoint temperature. Anyone? Oh - if it is the blower motor, how much should I expect to pay for the repair?