Did you ever figure it out? Mine is a gas furnace, pretty new (probably at least after 2000, maybe more like 05 or later). You can hear two distinctive switches when it comes on, I would guess the heat and the blower. But now, sometimes only the first switch clicks, after a min the second one flips, but then immediately flips back of. It's like the heat comes on, but the blower doesn't blow. Then it blows for literally less than 5 seconds, and goes off. Sometimes it flips back and forth several times in just a few seconds. Diagnostic lights show no errors, and changing the filter doesn't help. Haven't tried cleaning that rod yet because I am not sure I could find it.