Goodman furnace lights and goes out

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  #1  
Old 10-24-17, 08:07 AM
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Goodman furnace lights and goes out

Hello, I have a goodman furnace GSK91155DXAE. Recently the sump pump failed and my basement flooded, my furnace shorted out melting the board and some wiring. I've replaced the board, repaired the wiring, replaced the stepper coil, and also replaced the gas valve as it would blow the 3 amp fuse. The furnace lights for about 3 seconds then goes out. Reading on here I removed the flame sensor and cleaned with steel wool. Same thing, I took the sensor out of my other furnace that works. Same thing, I got to checking for power to the flame sensor and it shows 24 volts when the furnace lights. I thought I understood it should show mega amps? Does anyone have any idea what is going on? 36 degrees this morning, could use some heat. Thanks in advance
 
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Old 10-24-17, 08:34 AM
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If the flame sensor is good it should read between1-6 microamps.

Check the 12 pin connector on the module for water damage.
 

Last edited by skaggsje; 10-24-17 at 08:39 AM. Reason: added
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Old 10-24-17, 09:21 AM
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I've been through the connections, I assume you are talking about the molded plug or whatever they are called? The white connector that plugs into the board. Forgot to mention i jumped r and w terminal to eliminate the thermostat.
 
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Old 10-24-17, 09:24 AM
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Also is it supposed to show 24 volts on the flame sensor at anytime? I didn't have a good volt meter with me last night.
 
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Old 10-24-17, 09:47 AM
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It could show 24vac but it could also be higher. The flame sensor is just a metal rod. It's only function is to sit in the flame and conduct. Basically the flame sensor establishes a closed loop thru the fire. The only effective way to test it is to put a microamp meter in series with it.

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The diagram show the closed loop. You'll see ground is part of the loop. A good ground to the burners and the control box is critical to the flame sense process.
 
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Old 10-24-17, 10:40 AM
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I'll check it again today
 
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Old 10-24-17, 04:20 PM
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Ok so on innatial light up the flame sensor reads 1.34. After a second it drops to .734 then goes off.
 
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Old 10-24-17, 04:35 PM
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Volts or mA? Which were you measuring?
 
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Old 10-24-17, 05:10 PM
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Ma is what I was measuring
 
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Old 10-24-17, 06:06 PM
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That's probably ua you were measuring.
ua = microamp
ma = milliamp

1.34ua and dropping is too low. You should get better than 2ua.
Make sure the rod is engulfed in the flame.
 
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Old 10-24-17, 06:22 PM
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I just checked again. On ma. Not sure if I'm hooking up correctly. Positive lead to sensor wire, and negative to flame sensor.
 
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Old 10-24-17, 06:23 PM
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What is the make and model of the meter ?
 
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Old 10-24-17, 06:35 PM
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Snap on EEDM525D is my volt meter
 
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Old 10-24-17, 07:32 PM
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The connection polarity is not important. Move the black lead to the uma port in black circle. Try the test with meter set to 40ua.

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Old 10-24-17, 07:57 PM
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Thank you. I did the test the way you showed. Black lead moved to uma port. one lead to flame sensor wire, the other to the flame sensor. did it 3 times .65, .67, and the last .65. What does this mean? Thanks for your help.
 
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Old 10-24-17, 08:29 PM
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The burner was igniting during your testing.... correct ?
That is low as you need approx 2ua to keep the board satisfied.

Make sure the burner is grounded. If questionable add star washers to the screws.
Make sure the control board is well grounded.
Make sure the flame rod is directly IN the flame.

As you make changes and improve the grounding.... that reading should start going up.
 
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Old 10-24-17, 08:53 PM
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Yes the burner lights for about 3 to 5 seconds. I ohmed the green wire from the house ground to the burner, it is good. I read somewhere people were adding grounds. I might try that. But the only thing on the board that I see is the white common's. Im not near the furnace now, unless the green in the moldex plug is a ground. Ill do more tomorrow. I appreciate your help. About to start pulling my hair out..
 
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Old 10-24-17, 10:29 PM
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The burner to frame and control board to frame needs to be 0 ohms. Most generic meters won't read accurate enough below several ohms. Since your furnace was under water I'm thinking poor metal to metal connections.
 
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Old 10-25-17, 06:30 AM
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I ran the bare house ground directly to the burner frame, then tied the other green wires to it. Added a wire to the screw on the flame sensor screw. Ohmed the green wire to the moldex plug it is good. Retested the wire to the flame sensor and it still is 65- 66.. what else can it be?
 
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Old 10-25-17, 09:50 AM
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You have your meter in series with the flame sensor rod.... correct ?
Your meter reads 0 when the burner is not lit.... correct ?

I'm leaning towards a problem with the control module.
 
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Old 10-25-17, 01:29 PM
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I had one lead in the wire, the other on sensor terminal. Reads 0 until it lites.
 
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Old 10-25-17, 02:54 PM
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OK... so you have it connected correctly.

The circuit is very simple. An AC voltage is applied to the flame sensor (you measured 24v which could be low). The flame sensor rod is in the flame. When the flame is present..... it actually causes a DC current to flow from the rod thru the flame to ground. Flame rectification. That current is what you are reading. That reading very rarely stays the same. As the flame changes so does the current thru the circuit.

That leaves four areas for problems...
1) dirty flame rod or not fully IN the flame.
2) poor ground between the burner assembly and the control board.
3) an intermittent/dirty connection at the 12 pin plug.
4) a defective control board.

If 1, 2, and 3 are ok..... that leaves a defective control board.
 
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Old 10-25-17, 03:29 PM
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I'm leaning toward the board also. But I'm sick of the deal. I have a guy coming in the morning to check it out. I do appreciate your effort. Thank you so much
 
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Old 10-26-17, 10:31 AM
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Ok, my furnace is fixed. The problem was that the flame sensor wire went to the 12 pin connector. The new board had a separate terminal for that wire. So in short, cut the wire put a female spade connector on and plug it in. Problem solved. I didn't see in the instructions anywhere to do that, the hvac guy didn't either. Hopefully this can help someone else. Thanks to everyone for the help.
 
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Old 10-26-17, 09:35 PM
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Glad you found the problem. When you said a separate terminal for flame sensor.... it clicked. The terminal is labeled FS on the board. There is a similar thread running but the member can't get his igniter to work. His board also had the FS terminal.
 
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Old 10-29-17, 09:49 AM
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Well the furnace worked all of thursday, and late Friday night it stopped. Inducer and blower both running. Flashing 5 times, I believe it said flame sensed without gas valve. There is no flame or gas. I tried resetting it. Unhooked the flame sensor wire, same thing. I think now the board has a problem. Would you agree? Or do you have any different ideas?
 
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Old 10-29-17, 09:58 AM
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If the fault code indicated flame presence and the probe was unplugged... that would be a board problem.
 
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Old 10-29-17, 11:12 AM
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Thats what I thought too. Thanks again. This furnace is going to drive me to drinking..
 
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Old 11-01-17, 03:57 PM
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I'm back, I replaced the board last night. Came home tonight to the exact same thing. Both fans running, blinking 5 times. What can be burning up the board?
 
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Old 11-01-17, 04:41 PM
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That doesn't make any sense. A flame detected without a call for heat should not be running the inducer and main blower.

Can you verify that the 120vac is connected correctly. Verify at the board by measuring from the the neutral locations to ground and 0v should be found.
 
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Old 11-01-17, 05:16 PM
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I wasn't real clear, sorry. The fans only run with call for heat. If I unhook the thermostat wires it doesn't run the fans. I just checked voltage from neutral on board to bare copper ground and it was .066 then went lower the longer it was hooked up, ending at .001
 
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Old 11-01-17, 09:05 PM
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Dave.... I'm running out of ideas here. The mains wiring sounds correct. Hot and neutral reversed could cause weird problems.

When you shut the power down and restarted..... did the furnace work normally or come up with that 5 fault code ?

I'm wondering if the furnace was operating and the call for heat ended but the valve did not close causing that 5 fault code. Just firing up the system shouldn't cause that fault as there is no flame.
 
  #33  
Old 11-01-17, 09:27 PM
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Does it give you a code 5 if you unplug the flame sensor wire?
Is the flame sensor porcelain base cracked?
Is the flame sensor rod touching metal? ( It souldn’t be)
Does the flame sensor wire insulation appear cut?

What voltage do you read from the flame sensor wire to ground?
What voltage do you get from 24VAC C to 120VAC Neutral? ( want less than 3VAC)
 
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Old 11-02-17, 09:44 AM
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The furnace doesn't work after power down, I haven't found a way to make it work other than a new board. And with them only lasting one day soon i will have the price of a new furnace invested. It still gives the same 5 flashes even with sensor wire off of the board. As far as the voltage testing it'll be Friday evening before I can get back to working on it.
 
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Old 11-03-17, 05:47 PM
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I wanted to get back to you with an update. The board I have replaced 2 times is a White Rodgers, I couldn't find anything wrong with the furnace as you know. So I called the company tech support line. You'll never guess what they said, and I quote "we have been getting a ton of calls about flashing code 5" They suspect a bad batch got sent out. They wanted the date code from my boards and they both are in the range of the bad ones. They claim to be sending me two replacements and shipping labels to send these back to them. I do want to thank you again for all of your endless effort to help me get my heat fixed.
 
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Old 11-03-17, 06:57 PM
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An error in the board programming. Rare but does happen.
Thanks for letting us know what you found out.
 
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