Atwood Furnace - Ignition Lockout Fault
When I turn on the furnace, blower comes on for a few seconds, then the gas and ignitor - it ignites and burns for about 5 sec (with ignitor clicking entire time), then gas and ignitor shut off, blowe...
Forum Discussion
Ok Starts. then shuts off (3 times) then locks out Each time it lights but then shuts off.. Sounds very very very familure (As in I had that problem).
Suspect list:
An obstruction in the burner orifice (Gas jet) or elsewhere can cause a weak flame. I do not think this is it
A deffective thermocouple may not detect the flame. I've heard of this but again I do not think it is common.. If it's all cruded up with carbon it might be and issue.
Bad connection between Thermocouple and mother board (NOTE on a single wire system the wire is the ignition wire) this can do it. After all ignition is like 1000 volts AC and Sense is 1/2 volt DC so the kilovolt will overcome a bad connection and actually make it worse.. However again I think rare.> Still easy to check (just pull and reconnect the connectors a few times each one on each end of the wire)
Bad control board (Motherboard) DING I found my winner..
THeory (And support to follow) is that if the swichover from SEND SPARKS to Look for .480 volts from thermocouple goes flakey then the sensor chip gets hit with up to 1500 volts and POP goes the wafer. So no heat sense.
Solution was a new board from DINOSAUR boards.
Support for my theory: ON the Dino broad right about where I suspect that sensor chip is there is a nifty gas discharge tube. This tube is a "Surge Suppressor" type device (like the MOV in a power strip) that clips and limits the voltage to something the sensor chip can withstand.
My Guess is that Dinosaur Boards and I think alike on this issue.
Other comments: I am a trained Certified Electronics technician who has designed and built some of his own hardware. My initial impression when I took the Dino board out of the box was QUALITY!!!.. and nothing since has changed that impression .. Oh that was 2012 (Feburary) when I opened that box. it still works.
Suspect list:
An obstruction in the burner orifice (Gas jet) or elsewhere can cause a weak flame. I do not think this is it
A deffective thermocouple may not detect the flame. I've heard of this but again I do not think it is common.. If it's all cruded up with carbon it might be and issue.
Bad connection between Thermocouple and mother board (NOTE on a single wire system the wire is the ignition wire) this can do it. After all ignition is like 1000 volts AC and Sense is 1/2 volt DC so the kilovolt will overcome a bad connection and actually make it worse.. However again I think rare.> Still easy to check (just pull and reconnect the connectors a few times each one on each end of the wire)
Bad control board (Motherboard) DING I found my winner..
THeory (And support to follow) is that if the swichover from SEND SPARKS to Look for .480 volts from thermocouple goes flakey then the sensor chip gets hit with up to 1500 volts and POP goes the wafer. So no heat sense.
Solution was a new board from DINOSAUR boards.
Support for my theory: ON the Dino broad right about where I suspect that sensor chip is there is a nifty gas discharge tube. This tube is a "Surge Suppressor" type device (like the MOV in a power strip) that clips and limits the voltage to something the sensor chip can withstand.
My Guess is that Dinosaur Boards and I think alike on this issue.
Other comments: I am a trained Certified Electronics technician who has designed and built some of his own hardware. My initial impression when I took the Dino board out of the box was QUALITY!!!.. and nothing since has changed that impression .. Oh that was 2012 (Feburary) when I opened that box. it still works.
