Nordyne gas furnace

[Toddraptor660]

Has anyone had any experience working on an older gas fired furnace for a manufactured home?
This is an older nordyne unit .
model M1MB 070A BW
serial M1M991001840

The unit is going through its sequence of operation the hot surface ignitor is glowing red and the furnace will fire up for about three seconds, and then goes out.
it will then wait about 30 seconds and trys to refire again it fires up and gos out in about 3 seconds.

I am pretty sure it has to do with the flame sensor but there is no flame sensor on the burner assy I can see.

It has two yellow wires on the gas valve that go to an furnace control board 624602-A 9937

I am not sure how the system works as I have never seen a system that didnt have some sort of flame rod or sensor in the flame.

It has some sort of reflector that the flame blows against but i can find no way that this could be used to sense the flame.

Any help would be greatly appreciated.
Thanks,
Todd

[Gary]

On some furnaces, the ignitor senses the flame.

The pilot flame is being sensed or the main burner would not light.

Therefore I would suspect that the pilot flame is pulling away from the ignitor/sensor when the main burner comes on.

[Toddraptor660]

I appreciate the help I posted a similar post on HVAC-talk and recieved a bunch of smart A-- remarks.

Thanks for taking the time to respond even though I know this is suppose to be mainly refrigeration posts.

[Don78]

How many wires are going into the burner assembly?

[icecube51]

is there no metal pin ho has to be in the flames , we call it a ionization's rod or pen.sometimes the ionization is the ignition to. its to control if there is a flame ore not. when it sees no flame the unit stops for security reasons.it is possible to measure ionization whit multi meter on micro farads and has to be between 3 and 6 mF. the ignition can be good,but the ionization not. change the piece and try again.
good luck M8,

Ice

[Toddraptor660]

Found the problem the ignitor was just out of adjustment. The ignitor is used in this system to sense the flame Gary was exactly right.Readjusted the ignitor to 5/16" and refired furnace fired right up no problems flame looks good.
Thanks so much for the help everyone was very helpful that responded with no rude replys.
Thanks again.