I have a gas furnace in my attic, and I started the pilot light (which is
hitting the thermocouple) but when it is supposed to go on, only a very
slight blue flame emanates from the burner outlets and the fan does not come
on. I can turn the fan on down at the thermostat, but only normal air blows
out of the vents. I don't think it's a fan problem as the fan worked with
the air conditioner.

The small blue flames are easily snuffed out by the slightest breeze.

Any suggestions?