Fans run but no flame.


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Old 12-21-20, 10:05 AM
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Question Fans run but no flame.

I'm glad that I found this forum. I hope that I can solve my furnace problem. ( I hope to be able to help others, as I am a retired roofer and sheet metal mechanic.) I have an IC gas fired hot air furnace with AC. Model GNE075B12A1. The inducer and circulator fans start up when the furnace is powered up. So far, I changed the igniter/sensor and the gas valve. I checked the flame rollout limit switch and the pressure switch. So I have the fans running but no flame or glowing igniter. I have good air movement and a new filter. I'm thinking that the only thing left must be the board. The existing board doesn't show any LED. The fans run even with the thermostat setting on all possible combinations. I'm about to buy and install a new board, but as my bank account is getting lower, I'm hoping that there might be someone who can impart some HVAC wisdom to me before I buy the board. I have a gas fireplace in my living room, so we (me and Gumbo) are surviving. Thanks.
 
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Old 12-21-20, 10:12 AM
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Please, stop replacing parts with no diagnosis.
And note, since you installed a new gas valve youll have to check and set gas pressure. Gas valves are NOT plug and play.
Do you have power to the gas valve coil? Use your meter and test.
Any errors being displayed on the board?
 
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Old 12-21-20, 10:36 AM
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You're right on about my replacing parts before I knew the problem. Usually I'm smart about doing repairs that I have no experience with, but then sometimes all the information gives me brain fog and confusion, then I try something out of frustration. Dealing with natural gas is probably the most complex repair that I've attempted, but I'm already into it and really want to complete this. I bought the gas valve and now I know it's not the problem. I will check and set the gas pressure.
I do have power to the gas valve, I used a continuity meter. Not sure what the coil is.
My board doesn't show any LED display. After watching many YouTubes, I figured that because there is no light, then that means the board is cooked. What's your thought on that?
 
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Old 12-21-20, 11:39 AM
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What voltage is measured on the gas valve coil? It’s the connections on the gas valve.
If you have voltage, the next step is checking incoming and manifold gas pressure.
You need to do this before changing any more parts.
And will require a special gauge called a manometer. Gas pressure is measured in inches water column. Not psi.
 
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Old 12-21-20, 05:53 PM
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Both fans running are telling you there is a problem.
It can be an open limit switch or safety. If this was the case you'd be getting a fault code.
Since you aren't getting an LED..... you aren't getting 24vAC to the board. Could be a blown fuse or defective transformer.

You need to confirm you are getting 24vAC to the control board on the C and X terminals.



Technical support manual (downloadable)
 
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Old 12-21-20, 07:50 PM
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OK. Thanks. I got more work to do and tools to borrow. I was hoping someone would just say, "Oh that's easy. It's the board"
 
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Old 12-21-20, 07:54 PM
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No.... sorry...... you're not getting away that easy.
 
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Old 01-27-21, 06:16 AM
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One final update. I have a smooth running furnace and my house is warm. About the board. I said that no led was visible. Upon close inspection, the board has no LED. It must be an old model, but I got a replacement on Ebay for $50.00. Yes, I'm sure that I did some unnecessary work and wasted some dough. But the feeling of satisfaction knowing that I took care of the problem myself is very rewarding. And I saved a good lump of cash. Like I said before, I'm grateful for this forum. I want to fix everything myself, and mostly I've succeeded.
 
 

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