I have a lennox pulse furnace model no. gsr14q3-80 and when I turn the air conditioner on, the furnace hums and the outside air condition unit fan runs but the blower on the furnace will not run.

Does the fan work on fan on? Or during heat?

I'm having the same problem with mine but the blower WILL turn on if you run the heat but not the ac. The outside unit turns on but the inside unit does not. A hard slap to the front of the old Lennox will cause the blower to kick on after two or three loud ticks.