I need to change the fan on my Lennox furnace. Is this a big job or can I do this myself.

I may have misdiagnosed the problem, but, the heat is on, it just doesn't blow out of the vents, so I'm assuming that it's the blower fan that's shot.:confused:

It could be the Blower motor, fan relay, or the fan stat. I would do further checking before guessing it is the motor!

Try switching the thermostat fan selector to the on position (if present). Does the blower run?