That's why I added the little whistling emoticon. Showing sarcasm.
A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii
ran into samething yesterday that through me off right in front of the customer. I make a call for heat and the HSI lights the burners for about 2 to 3 seconds then the gas valve drops out. So presume the flame sensor is dirty, but wanted to check its output, so I put my meter in series with the sensor and wire, which on this furnace goes directly to the board. The micro amp readingon my meter fluctuated from I believe it was .1 to .2, but the thing that was wierd to me was the burners stayed lit this time. So I hooked it back up with out the meter and gas valve drops out. I cleaned the flame sensor up real good, only because my company doesnt have any stocked on my truck or I would have replaced it, and works fine now. That is the way I was taught to check them, and didnt know exactly what my reading was suppossed to be but it seemed low and I was pretty sure the flame sensor was the issue.
I had a similar experience with a Ruud unit. On the 80 percent units you might try reversing the polarity. This has worked for me twice now.