Coleman DGAT070BDD Flashes once

[Bullstok]

i have had many where the burner was a little dirty (or turned slightly grey) and i increased the reading several microamps by cleaning the area of the burner where the flame comes out from (3m scotchbrite pad). not saying that is absolutely the problem. but something to consider if the grounding of the burner has already been checked. also once in awhile the flame sensor rod gets glazed and touching it a little with small very fine file will help. (don't leave gouges, just very lightly)

p.s. a lot of boards only need 1 microamp

Edited October 26, 2012 by Bullstok

[hyprdrvr]

No luck on the manometer. At this point, everything leads to the new control board being bad. Ordered it online and missed the little note about no returns on circuit boards. I have emailed the manuf. (icm controls)...waiting for a response. Also,the temps have finally dropped to low 40s here in NW Louisiana, so I called the local coleman service tech. The will be here early next week to look at the recall issue. I'll have them figure it out if the manuf. can't/won't help me out.

[jb8103]

There is one thing left, stray voltage on the neutral.

[hyprdrvr]

How do I check that?

[jb8103]

Neutral is grounded at the panel. If there is any voltage between neutral and ground inside the furnace cabinet you have a wiring problem somewhere. I only mention it in case you did not specifically check for it when taking the long shot. It's just that voltage on the neutral, or ground of course, would definitely have an effect on our microamps.

Don't worry about the manifold pressure if your flame characteristics are good. Which they are.

That's all I have, hyprdrvr. Bon chance, and if you do get to the bottom of this, post back, won't you?

P.S. Use that borrowed Fluke meter to check this, you need a true RMS meter.

Edited October 29, 2012 by jb8103

[hyprdrvr]

Will do on the resolution post.

Don't have the fluke on hand. Bought a Klein MM200 to replcae the GB meter that was not reading amps correctly. Should have bought the MM2000 but did not think I would need true RMS or Low Impedance. Anyway, It's reading 0.074 VAC and 0.5 mVDC between house ground and neutral on control board.

[jb8103]

Sheesh, that's cleaner than usual.

[Daveb1972]

All furnaces that use flame rectification are sensitive to propper polarity. Chech the 110VAC supplu (black) to ground, and the same Neutral (white) to ground. If they are reversed this will occur.

flame sense values above 1.5 UA are usually enough to keep the control happy. I'd try to check burner ground as well, right where the flame would complete the circuit t ground from the flame sensor.