AO Smith FPS 50 Powervent Water Heater: Burner won't stay lit, blower keeps running
I have an AO Smith FPS 50 226 Powershot gas water heater. When there is a demand for hot water, everything starts up normally, but the burner goes out (can hear the solenoid click shutting it down) before the water is up to temp (the blower continues to run and the pilot is lit). While the blower is running, the burner may refire at some point, but then it shuts down again. If I reset it using the on/off switch on the blower, it will refire and continue to burn until it shuts off properly, though not always the first time. I've run some of the tests outlined by the tech manual, but it doesn't seem that this condition fits the ones covered. The blower, power cable (tested for 120 at both and got it), and gas valve solenoid are all fine (replaced the latter to no effect). The wire harness that connects the power cable to the gas pressure valve and solenoid is not showing 120 volts (in fact it shows 0) to the solenoid (according to the manual this could indicate that the harness needs replacement), but continuity is good in all 4 wires (no shorts). Haven't tested the gas valve for pressure yet, nor have I tested the gas pressure switch (though the conditions according to the manual don't point to this being a problem, and I'm not sure how to do that specifically even if it did). I know the water heater is old (about 12 years), but I'm not in a position to replace at the moment. Could it still be the harness, the gas pressure switch, or is there something else I should be looking for?
AO Smith FPS 50 226 - not working, please help
Most of what I know about water heaters is from the research I've done in the last 24 hours, so first of all i'm a total novice.
The water heater is 19 years old... given its age, the time of year and the fact that we're gonna have a dozen people here for Xmas I almost had a guy come out here today to replace it for a mere $1,800 (sorry kids, hope you enjoyed your shower). Anyway, I live in Minnesota and it has been crazy cold (if that affects anything at all, like -30). I have smelled trace amounts of natural gas lately so I shut off the gas valve last night... today, I turned it back on and lit the pilot, it stayed on, but after turning the knob to ON, setting the water temp to "A" (I assume means "average") and flipping the breaker back on, the burner did not light, the blower didn't do anything (I tested the outlet so it's getting power). A friend of mine said paying $1800 is just stupid and its probably a $10 thermocouple - another thread on this site claims the blower was clogged with dust was preventing enough air flow to initiate it working. I pulled the little air tube from one side and couldn't blow any consistent air through it, but while inhaling i could hear a switch of some kind - i tried the other way and couldn't blow or inhale much. I understand there are about 7 things that have to happen in order or it won't light the burner. Every plumber in town is crazy busy and may take several days to come out (unless they hear you have a check for $1800 then they'll be out in 15 minutes, ugh). I checked the exhaust tube on the side of the house, with the exception of a little icicle hanging off the bottom lip of it, it wasn't clogged. I don't know what to do other than maybe order a thermocouple. The blower is a 3000 RPM Ametek. Any advice would be so appreciated. I'm attaching a link to a short video of the burner area, not sure if it shows anything - kinda looks like a layer of crap needs to be cleaned off of it? please, help me save xmas... :(