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Goodman Furnace Gas Valve Not Opening
QUESTION:Need help troubleshooting a new installation of a Goodman 70K btu 95%
efficiency two stage gas furnace (Model GMH950703BXA). Brand new.
Replaced old furnace with new. Unit ran fine for about 30 minutes and
then cycled itself off. No flashing diagnostic light until tried three
times and then single diagnostic to indicate three failures and that
gas not being delivered to burners.
Gas pressure fine.
Unit cycles on, blower runs, igniter heats up but after 15 seconds
igniter turns off because flame senses nothing. Not sure why it will
deliver gas to burners anymore. I checked the gas valve while running,
after igniter heats up, I can confirm valve does not open. I know
valve is not the broken because I took valve from another new unit and
still same results. In fact, tried replacing every part except the
combustion fan
The only thing I can think of is that we did not do the direct
venting. While testing, left air inlet as is and combutsion out was
vented to existing flue from old furnace (4" flexible tube).
If venting was the issue, wouldn't the unit at least burn for a time
and then cycle off ? Now cannot get any gas to be released by valve to
the burners. Tried turning off gas, shut off gas valve, shut off
electricity, and re-started everything again, but same results. Tried
4 or five more times.
ANSWER: I had the same problem a coupla months ago with my 90K BTU Goodman 95%
2-stage furnace. The contractor installed the brand new unit, and
after a couple of days the furnace started behaving just like yours
is. I called the guy, he came back, opened up the front cover, looked
inside, but wasn't sure what it was, but somehow got it to work. Over
the next few weeks the problem reoccurred a couple more times, once or
twice it self-healed, but then it wouldn't come back on, so I called
the guy again. The second time, hew finally figured it out, and was
able to fix it. The furnace has been working fine for 4-5 weeks now.
Here's what it turned out to be:
If you remove the front cover, there is a black rubber hose inside,
about 5/8" thick, that is used to remove H20 condesation (from the
exhaust) and drain it out of the furnace (thru a pvc pipe.) Well, this
black rubber hose was originally about 2+ft long(orig. length "out of
the box long"?), so it was "bent and curved" by 180 deg inside the
furnace when installed. There was a section of the hose that was
forming a slight U-shape, and it seems that some H20 was just sitting
in there instead of being drained out. That's at least how the guy
explained it to me, and he thought that, for some reason, was causing
the furnace to go into lockout.
Solution: The guy used a pair of scissors/cutters to trim the rubber
hose to the total length of maybe 10 " and ran it to the drainage
opening (on the right-hand side of the furnace) in a pretty much
straight, slanted line.
I hope I am explaining this clearly enough. I was getting so pissed
and frustrated for a few weeks, and wouldn't want anyone else to have
to go thru the same experience.
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