I have an Armstrong Ultra Tech 80 furnace that won't light. The inducer blower comes on for about 30 seconds then shuts off and the ignitor never starts to glow. The LED code is 3 flashes. Things I've tried: I checked the hose to the pressure switch and the nipples - all are clear. I can get the pressure switch to click by sucking on the opposite end of the hose. I also jumped the contacts on the pressure switch and cycled the heat with the same results. I'm getting 24V on both sides of the pressure switch to ground. The flue is clear. I cleaned the residue off of the heat sensor with steel wool. Nothing works to get the ignitor to heat up and glow. The element in it doesn't look cracked or broken. I put a voltmeter on the connections to the ignitor with it unplugged, cycled the heat and didn't get a change in voltage. It justs stays a zero. Shouldn't I get a change in voltage from the leads to the ignitor at some point when the inducer blower comes on? Not sure what else to try. Any ideas? Thanks!