Goodman - http://www.hvacmechanic.com/ Forums
Original message
| bill1
 |  "Goodman"
, posted Sun 10 Feb 15:18  
I have a Goodman GMNT080-4 95% that will not meet temp
and also has ign fail code.
Has new hsi and flame sense. when ignitor lites I here a click on the CKT. board but no gas im getting no voltage at the gas valve after the relay clicks on the board sometimes it works good and sometimes not. and if i set t-stat to 72 it will only make it to about 68 or not work at all unless i reset it I have a Honeywell programmable t-stat had gas pressure checked checked intake and exhaust no problems there.
any help would be great thank you.
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Replies:
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| justsomeguy
| "Re(1):Goodman" , posted Sun 10 Feb 16:14
I'd check the vent pressure switch but you probably don't have a magnehelic gauge. i have replaced so many of those switches on that system this heat season that I have lost count.
BillyBob
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| | bill1
| "Re(2):Goodman" , posted Sun 10 Feb 16:20
Thanks JSG
if i jump it the furnace does the same thing
if i pinch off the hose it shuts the furnace down
so i think its working right i hope
thank you
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| jbwstroker
| "Re(1):Goodman" , posted Sun 10 Feb 15:25
Why were the HSI and FS replaced? Hopefully not just changing parts. Make sure there are no loose or disconnected wires anywhere. Check the connections on the wiring harnesses. If your getting ignitor glow followed by a relay "click" without 24V at the GV terninals, it's probably a bad IFC board assuming all wire connections are good.
"I'd probably be considered an old wise man if I could only remember everything that I've learned".
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| | bill1
| "Re(2):Goodman" , posted Sun 10 Feb 16:17
Hey JB thanks for the reply
the hsi and flame sense were given to me to try them they are correct. I know that's not way to do things though just thought i would try them.
I just noticed though that with the furnace door off it seems to work fine.
so is it intake air,temp I don't know anymore.
baseball bat might work good at this point.
Thank you
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| | tom446
| "Re(3):Goodman" , posted Sun 10 Feb 16:57
If it works with burner door off, I'd lean towards blockage in air intake or exhaust pipes, perhaps ice or water. Make sure your exhaust has good pitch back towards the furnace so that water can't lay in it.
If in doubt call a pro !
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| | bill1
| "Re(4):Goodman" , posted Sun 10 Feb 17:25
Thanks Tom
I am gonna try to run fish tape through both last time I checked they were clean. its three inch all the way 1 90 and two 45s on the exhaust side. intake side is three inch 1 90 1 45 witch I can feel cool air coming in.
I am at wits end. thanks for your help guys.
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| | tom446
| "Re(5):Goodman" , posted Sun 10 Feb 17:55
While your inducer is running, go outside and listen to your exhaust. A lot of times if there is water in it you can hear it gurguling,
If in doubt call a pro !
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| | bill1
| "Re(6):Goodman" , posted Sun 10 Feb 18:24
Hey Tom there is some condensation in the trap but its not dripping water. Where does the condensation come from?
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| | tom446
| "Re(7):Goodman" , posted Sun 10 Feb 19:14
You have a condensing furnace.The condensation is normal, most of it comes from your secondary heat exchanger. This is why there is a condensation drain system built into the furnace. It is normal for the trap to have water in it. However on a yearly basis you should carefully pull the incoming and outgoing hoses on it to make sure they are clean and unobstructed. I pull my trap and clean it annually with white vinager and hot water.
If in doubt call a pro !
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| | bill1
| "Re(8):Goodman" , posted Sun 10 Feb 19:55
Thanks tom Just pulled the draft motor and tube cleaned
I noticed tom that there is a crack in the black plastic box that the draft inducer screws to. not big but a hairline crack about 6" long.
When i took the motor off behind it in the black box it had about 1/2" of water in it behind a white rubber cap
ran a fish wire through the exhaust pipe no blockage
thanks again tom
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| | bill1
| "Re(7):Goodman" , posted Sun 10 Feb 18:57
I see a lot of different threads on different sites for this same furnace with the same problems to no avail
Do they have a tech support number.
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| | mule
| "Re(8):Goodman" , posted Mon 11 Feb 15:41
Remember your P.Sw. is tested twice by board on start up! 1st to make sure its not stuck closed.,then that it does close by ind.motor. It is a N.O. switch.normally open. Test with ohm meter.
"Its only Tin!"
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| | bill1
| "Re(9):Goodman" , posted Mon 11 Feb 19:18
Thanks mule
I did a test with my meter I have cont when I put vacuum to it
Open when I take it away
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| | bill1
| "Re(10):Goodman" , posted Mon 11 Feb 19:20
Also I get a real hard light off
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