I have an 8-yr old Armstrong Ultra SX 80 forced air gas furnace with Honeywell controls. My blower runs, but the furnace quit lighting last night. I tried some diagnostics that I found on this site, and what I have so far is:
1) I don't smell much gas, but that's probably due to the good airflow/draft.
2) My vacuum line is clear with no condensation. The vacuum is fairly light, so I tested with manual suction. I can hear the pressure switch activating, but still no ignition.
3) I hear no click from the spark ignitor. With an OHM meter, I get resistance through the 'sense' wire to the ignitor, but no change in resistance through the 'spark' wire.
Is the ignitor a likely candidate ?
Model # GUJ125D14-1A
Ignitor tag: Honeywell 204470DB
Thanks in advance for any advice.