Have a 6 yr old comfortmaker NDN3/NDF furnace and fan seems to be blowing all the time. Everything seems to be clear and everything but it does not seem to be igniting even if I crank the heat level up on the thermostat. Have a honeywell thermostat and I changed the batteries just in case it was that. Any suggestions before calling the company that installed the furnace. Thanks.:confused: :confused:

It could be a drity flame sensor/ignitor. Turn off furnace main power and clean sensor with sand paper (carefully)then turn back on and see if that helps the situation.
Your manual is below

http://icpindexing.mqgroup.com/documents/086477/44101260302.pdf