Goodman Furnace Gas Valve Not Opening


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.
Any suggestions would help.
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snipped-for-privacy@hotmail.com wrote:

You tried a gas valve out of another new unit?
Did you try another control board? (Maybe I missed that...)
Does the pressure sensor close after the inducer runs?
I gather this is some temporary setup with venting. Don't see how that would affect it.
Is the electric service to the furnace control properly Grounded AND is the polarity correct? (Wh Neutral, Blk Hot) The control is very sensitive to those conditions.
Jim
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Is the gas valve getting power during the ignitor warm up? If so, you likely have a bad gas valve. If not, I'd look for some notes about how many amps the HSI draws. I worked on a unit that had a HSI that glowed nicely, but the amperage draw was wrong. So, the valve didn't think the HSI was working properly.
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On Feb 20, 2:18 pm, snipped-for-privacy@hotmail.com wrote:

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.
Please post an update as to whether you were able to get your furnace fixed. I'll be very curious.
Good luck!
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replying to bubbabubbs, Bob wrote:

I had exactly the same problem. I had tried everything I could think of. Finally I called the installer since the furnace was only 3 years old and still under parts warranty. He was scheduled to come out the next day. While I was waiting for my wife to dress to go shopping I decided to do an internet search and found this write-up. After reading about the condensation drain hose problem it referred to, I went and squeezed the hose over its entire length since it was very flexible. I then made sure the hose had a drain slant (i.e., no dips) over its length. I estimate that about a pint of water drained when I did this. After that I turned on the furnace and it worked like a charm (at least so far). Thank you for your input!
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On Thursday, January 2, 2014 at 7:44:01 PM UTC-6, Bob wrote:

Bob ... You are a genius. How you determined that the problem was the hose filling up with water is beyond me. I disconnected the hose which had a sli ght "belly" in it, drained a half pint of liquid, shortened the length of t he hose, and reconnected it... making sure it was on a continuous slant dow nhill the entire length. Furnace worked like a charm ! I was curious why the furnace worked all last winter but I figure it was in itially installed in the dead of last winter when there was low humidity. t he condensation never built up until I started it up this year. Thanks aga in. Tom
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Tom wrote:

pipes connected to AC evaporator pan drain then straight down to drain in the basement floor. No such problem either on AC or furnce. I bet the problem will recur unless you make sure same standing water problem happens.
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I wonder if the fact that the hose was clogged with water had somehow an effect on the overall air flow araoudn the unit and that was the problem.
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On Thu, 2 Jan 2014 20:41:13 -0800 (PST), " snipped-for-privacy@sbcglobal.net"

"sail switches" would not turn off or on - preventing the unit from firing.
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On 1/3/2014 8:01 AM, snipped-for-privacy@snyder.on.ca wrote:

similar problem. Because the combustion air on this model is from inside the house (basement), it would pick up any dust, etc. in the air. This particulate would then form what I referred to as slime balls inside the drain tubes. There were 2 drains, one from the combustion blower and one from the secondary heat exchanger. Usually the one from the blower would clog. Initially it would start and run for a really long time before combustion. Apparently, it would have to slug enough water away from the blades in order to get enough negative pressure to then allow the gas valve to open and start. If you let it go for a long time, eventually, it would never open the gas valve; only the combustion blower would run. I found that, because of the basement layout, when the furnace was installed, I had to change the side where the drain was located. So, there was a small coupling in the drain line. The line was PVC with a short rubber hose on each end. Apparently, the roughness inside the solid pipe, where the coupling was located, was enough to catch the 'slime balls' and would build up until the line was clogged. I changed out the drain line to a single clear plastic line. Now you can actually see if a clog was forming. But, because there was no roughness inside, it never did. However, I would periodically take out the drains and clean any deposites with a small bottle brush and lots of water.
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On Tuesday, February 20, 2007 at 4:18:27 PM UTC-5, snipped-for-privacy@hotmail.com wrote:

I just now went out and with a length of old hose shoved it down both exhaust pipes if you will and works like a dream.
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snipped-for-privacy@gmail.com wrote:

If in lpock out mode, it takes I think 2 hpours before you can start the unit again. You can rest the unit by turning power on/off. Control board has test point to ground to test the unit. Tried or cleaned flame sensor?
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even those of us using Google Groups can see the dates of a post.
Mark
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