OK gang, I've been searching high and low and still haven't found the one piece of information I need. Like several others in the past, I have a problem where my furnace blows, but will not ignite. This is on a '97 Jayco with Atwood 79 series DSI type furnace. It seems like everything is working as it should, but I can't get it to ignite. This all started one night last spring on a chilly night in the mountains. Furnace was working fine when I went to bed, but midway through the night I noticed it was only blowing and not firing. Decided I'd finally have a look at it today before the weather cools off again up in the high country. Stove & water heater both work fine. Here's what I've done / observed:
1) I jumpered out my thermostat to force it on (it's still 100 degrees here in Phoenix today & thermostat won't go that high). Voltage seems to be getting to where it needs to be. Through the overtemp switch, through the sail switch, and onto the DSI board.
2) Blower comes on like normal for a few seconds and then I can hear the gas valves open up with a solid 'click'. About 5 seconds later they close. They open up again a few seconds later, then close again in about 5 seconds or so. This happens 3 times as the manual indicates it should, but no ignition occurs.
3) I removed the burner assy. and electrode to inspect them and found them to be very clean and in good shape. Spark gap on the electrode is right at 1/8". I rigged it up so I could see the spark on the electrode outside the burner box, and I get 1 single spark at exactly the same time as the gas valves open each time.
4) Verified gas valves are opening by gently blowing through them and putting 12V on the coils. They open very firmly and I get good flow through them.
5) Switched to the other full propane tank (dual tank setup w/ automatic switchover regulator), but that didn't help. Have also tried it using both battery and shore power - same result.
6) Disconnected the propane line at the furnace and underneath the camper, and blew the line out with compressed air.
The question I have after all of this is about the spark ignition. As I stated above, I only get 1 single spark at exactly the same time the gas valves open. It would seem to be much more effective if it sparked several times 'after' opening the gas valve. I don't think the gas can even get from the valve, through the burner, and to the electrode that fast. Is it supposed to do just one spark, or should there be several in rapid succession? Any help would be appreciated, this is very perplexing.
Thanks for helping,
Never get so busy making a living that you forget to make a life.
Edited by - DRas on October 05 2008 20:53:58