[uvalaw]

I recently purchased a Johnson Controls 031-01140-000 furnace control board. According to the eBay seller, it is supposed to be compatible with the 031-1234-000 board, which is the burnt out one I'm replacing.

When I install the new board, only the AC works. If I set the thermostat to the fan or heat, I get nothing. I have two identical furnaces in my house (the other one being in working condition).

I tried the new board on the other furnace and get the same results, which leads me to deduce that something's wrong with the new board.

The LED fault light on the new board corresponds to "reversed line voltage polarity or grounding problem . . . Check polarity at furnace and branch. Check furnace grounding. Check that flame probe is not shorted to chassis."

I've compared the wiring diagrams for the old and new boards and can find nothing different.

Does anyone have any ideas?

Thanks.

 

[Marty S.]

Safe to assume you changed the polarity and check the ground then?

 

[Technow]

Why did you replace the board in the first place?

 

[uvalaw]

Marty, yes I've reversed the polarity and checked the ground.

Technow - I had replaced the ignitor, which had burned out, but for some reason the new ignitor melted down when I started the system and took the control board with it.

 

[Doc Holliday]

Marty, yes I've reversed the polarity and checked the ground.

Technow - I had replaced the ignitor, which had burned out, but for some reason the new ignitor melted down when I started the system and took the control board with it.

Correction, the control board was going bad, sending too much voltage to the ignitor and melted it me would have to believe as the board is in charge, not the ignitor. Not until the board says so at least.

"They don't say Hanes until I say they say Hanes."

 

[Technow]

Correction, the control board was going bad, sending too much voltage to the ignitor and melted it me would have to believe as the board is in charge, not the ignitor. Not until the board says so at least.

"They don't say Hanes until I say they say Hanes."

Ignitors work on the same voltage as what comes into the board. :whistling2:

 

[Doc Holliday]

Shut the power off to the furnace by breaker or disconnect and put the stat in the off position.

Disconnect the red wire at the stat from the "R" terminal, disconnect the green wire from the "G" terminal and disconnect the white wire from the "W" terminal at the stat.

Wire nut those three wires together, turn the power back on to the furnace. Now you have bypassed the stat and it should be calling for heat.

Start there to make sure the stat is good.

You can jump from those same three terminals on the control board as well to see if heat comes on by you telling the system to come on physically instead of the control board. Tell tale sign of it is is no good as if it comes on with those wires being jumped then the control board is not controlling anything, if you are jumping them there but you should probably check the stat as well as it may not be telling the board to go on into heat or fan.

If heat comes on by bypassing the stat, when you connect the r, the w, and the g from the stat together, then your stat is bad.

 

[Doc Holliday]

Ignitors work on the same voltage as what comes into the board. :whistling2:

"Lucy, you half sum splainin' to do!"

whoopsie.

 

[beenthere]

Marty, yes I've reversed the polarity and checked the ground.

Technow - I had replaced the ignitor, which had burned out, but for some reason the new ignitor melted down when I started the system and took the control board with it.

How did you change the polarity?

 

[beenthere]

Ignitors work on the same voltage as what comes into the board. :whistling2:

Generally, some ignitors are 24 volt, and some are 120 volt.

And now Trane has gone to a smart ignition systems that checks what the lowest voltage is that will ignite the gas, and varies its voltage until it finds that voltage.

 

[yuri]

Ignitors work on the same voltage as what comes into the board. :whistling2:

Not totally true. Lennox uses 83 volts and that reducing voltage system Beenthere mentioned. They have 6-12 different igniters with different voltages so you must match it to the specific board.

Uvalaw, Post the make model and serial # of the furnace so we know what you are working with.

 

[uvalaw]

Shut the power off to the furnace by breaker or disconnect and put the stat in the off position.

Disconnect the red wire at the stat from the "R" terminal, disconnect the green wire from the "G" terminal and disconnect the white wire from the "W" terminal at the stat.

Wire nut those three wires together, turn the power back on to the furnace. Now you have bypassed the stat and it should be calling for heat.

Start there to make sure the stat is good.

You can jump from those same three terminals on the control board as well to see if heat comes on by you telling the system to come on physically instead of the control board. Tell tale sign of it is is no good as if it comes on with those wires being jumped then the control board is not controlling anything, if you are jumping them there but you should probably check the stat as well as it may not be telling the board to go on into heat or fan.

If heat comes on by bypassing the stat, when you connect the r, the w, and the g from the stat together, then your stat is bad.

Doc Holliday: Thanks for the tip on jumping the wires at the control board. I had already swapped the stat with another one in my house (known to be working properly) with the same results. So I know it's not the stat. I'll try jumping it at the control board.

 

[uvalaw]

Not totally true. Lennox uses 83 volts and that reducing voltage system Beenthere mentioned. They have 6-12 different igniters with different voltages so you must match it to the specific board.

Uvalaw, Post the make model and serial # of the furnace so we know what you are working with.

York Model # P1UKD08N0321; Serial # EGBM239477

The wiring diagram that came with the furnace is here, if anyone's interested:

http://a1.sphotos.ak.fbcdn.net/hphotos-ak-snc6/215076_912439536706_1505837_46233127_4348270_n.jpg

The wiring diagram for the new control board is here:

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/205457_912439556666_1505837_46233128_4321251_n.jpg

 

[yuri]

Switch the 2 secondary wires (24 volt side of the transformer) on the circuit board. The old boards on them were not transformer polarity sensitive but the new ones are and I had to do that with one. Polarity applies to the secondary side and not just the hot/neutral to the furnace. Secondary side of all transformers on modern furnaces is grounded and the board checks that B4 startup. They don't explain that with the instructions.
Put the high voltage hot/neutral back the way you found them and make sure the hot is hot and the neutral is not hot.

 

[uvalaw]

Switch the 2 secondary wires (24 volt side of the transformer) on the circuit board. The old boards on them were not transformer polarity sensitive but the new ones are and I had to do that with one. Polarity applies to the secondary side and not just the hot/neutral to the furnace. Secondary side of all transformers on modern furnaces is grounded and the board checks that B4 startup. They don't explain that with the instructions.
Put the high voltage hot/neutral back the way you found them and make sure the hot is hot and the neutral is not hot.

Thanks for the suggestion. I tried that, but I still get no fan control from the thermostat. When I turn on the heat from the thermostat, the blower starts to run and gas turns on, but the ignitor does not light up.

 

[beenthere]

Could be a bad ignitor.

 

[yuri]

Yep, do you know the ohms rating for that one, Beenthere? Check for continuity with an ohmeter and see if it has a voltage rating on the plastic molex plug of the igniter. Probably 120 volts. If so check for that when the gas comes on. Check the pins in the molex connector on the igniter and the cables on the board. One may have backed out and you have a bad connection. Use a magnifying glass.

 

[Ducthunter]

Ignitors work on the same voltage as what comes into the board. :whistling2:

Unless it's a newer trane they only get 80v