MGHA-066AAFC-01, pilot's fine, but won't stay lit>?

[jag7777]

I have an MGHA-066AAFC-01 that i recently changed the thermocouple on, but i still am having a problem: my pilot lights fine, then when i move the gas valve to the ON position and the gas kicks on, it burns fine for about 5 to 7 seconds then everything is blown out (including the pilot), it's like it's starving for air - the reason i say this is i've had the pilot/gas tube out of the furnace hooked the two wires back up, and it works just fine - even when i just sat this unit inside the furnace it stayed lit, it now had more air flowing in thru the 'plate-hole' of course, and short-cycled like it always has (but thanks to you guys i know how to fix that now). It's like it's starving for air>? the flames, with the plate put back on, turn real blue, and poof - everything is now out. I've re-lit it several times to no avail. Where is the fresh air return anyway>? Is it in the same tube as the exhaust vent - it looks like it to me. I assume it's the vertical tube just to the right, inside the furnace when facing it - with the front panel off>? Any help would be greatly appreciated! Thanks for such a great forum too - i've learned alot here. jag7777

[Robert]

Hi,

Yes, there is two pipes, one inside the other. One brings in combustion air and the other vents the exhaust gases.


Inspect it closely for blockage, damage or seperation of pipes.



Thanks,
Robert

[jag7777]

Thank you Robert! Oh, and i'm the humbly grateful type, BTW. Meantime, i'll be on the roof and inspecting those pipes very closely. Thank you again so much! Excellent website!
jag7777

[Robert]

Hi,

You're very welcome, happy to help.


Take care and best wishes,
Robert