Originally Posted by shortensweet
There is a reset switch up at the pressure draft safeguard, try to reset it, if you hear a click that was the problem.
Also I would look for all of the safety switches and make sure all are intact and do not need to be reset,
One other suggestion, I would try this one first. Unplug your furnace, turn the thermostat to the off position, and wiat for about five minutes. Now make sure doors are all in place, plug the furnace back in and turn the thermostat to the heat position and make sure the temp is set higher that the actual temp.
Here is another check, take the doors off, use a piece of tape over the door switch to make sure it is held in place. Turn the termostat to the off position, then read the instructions about a test terminal, I think it says jumper from the test terminal to the common terminal on the low voltage portion of the circuit board, hold this for just a second, the furnace will then go through each phase of the cycle except turning on the fire.