American Standard Freedom 80 not lighting

tehDorf

I have an American Standard Freedom 80 that is about 10 years old. At the end of winter last year it stopped heating the air but kept circulating it, pushing cold air through the vents. Now that it is starting to get cold again, I climbed up into the attic to check on it and found that the hot surface igniter was broken, the tip was broken off and it didn't get hot even though it had about 105 volts A/C.

I went to the hardware store today and picked up a universal hot surface igniter from Home Depot to replace it, wired it up, and mounted it. When the furnace kicked on it glowed red hot so I thought my problem was solved. After a few more seconds the gas came on for about four seconds, but it didn't light. The furnace would cycle the HSI and gas a few more times before the blower turned off and the fan turned on. The control board's LED was blinking constantly before, but switched to just two blinks after the blower shut off and the fan started. I thought the igniter might not have been in the right place, but even after adjusting the HSI it still wouldn't light.

I'm not sure where to go from here, it seems like it should be working. I have a few ideas but I'm not really sure how likely they are:

1) The hot surface igniter is not getting hot enough. It glowed red hot, but the picture on the box shows it getting white hot. I wonder if it is supposed to be getting 120 volts (110 is the lowest I recall reading online) instead of 105 volts I measured.

2) The hot surface igniter is not positioned correctly. I picked the bracket that I thought was the closest, but I don't think it is in the same spot as the original. I don't really think this is the problem though because I moved the HSI around and even put it right in front of the gas diffuser (not the initial jet, just to be clear) but it still didn't light.

3) The gas jets are dirty and need to be cleaned. This seems less likely because I felt them and they felt clean and smooth, but I wasn't able to see them because of the angle.

raylo32

I would check the manual for the blink code. The manuals are often affixed to the appliance by the installer. That would give you some valuable info...

tehDorf

The two blinks mean "System Lockout (Retries or Recycles exceeded)". I assume this is referring to the three or so failed attempts to light the burners. Not very helpful.

raylo32

Not an xpert... just another DIYer... but can you see that the inducer motor is running? Do you hear the gas valve click or clack open and hear gas come out?

JJboy

If igniter is Silicon Carbide HSI you should have 120vac at the connector.
If igniter is Silicon Nitride HSI you should have 70~80vac at the connector.

Is gas valve ok?

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**Always kill the power ** Hot air rises, but heat will always move from higher to lower temperatures. ** Real man shoot in manual. ** If it ain't grounded, it ain't dead.

tehDorf

@JJboy
I'm not sure what kind I have but I think I should have the Carbide HSI. Assuming I grabbed a Carbide replacement, would it not work if there was only 105vac?

Yes, the gas works. I can feel the gas flow out of the jets and I can smell it too.

JJboy

Disconnect the igniter.....you can measure the voltage at the connector (cable ) and controller board.....should be the same voltage.

When the igniter glows do you see any flame at the burners? or you see the flame at the burners and after a 3 second shuts down?

Check is the igniter cable goes to the controller board ou smart gas valve....

__________________

**Always kill the power ** Hot air rises, but heat will always move from higher to lower temperatures. ** Real man shoot in manual. ** If it ain't grounded, it ain't dead.

hvactech126

The universal replacement from HD is a silicone nitride 120V replacement for 120V silicone carbide ignitors. Most likely the ignitor needs repositioned because you used a universal ignitor.

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tehDorf

Okay, so I re-measured the voltage supplied to the HSI. It moves between 70 volts and 109 volts. It stays around 70, but moves up and spikes around 109, then quickly drops back down to 70. Does this mean I need a Silicon Nitrate HSI that operates at 70-80 volts? Or is there something wrong with my furnace/replacement HSI?

hvactech126

can you post a picture of your old ignitor. Also please post your model number. Look on the control board for a control board model number.

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tehDorf

Here is a picture of the old (bottom) and new (top) HSIs. The old one is a Trane B340971 P01. The furnace model number is ADD080C936E. Model year 2000, I believe.

hvactech126

you have a 80V nitride system, the replacement will not work with your system. You need an OEM ignitor. They have been upgraded, if I remember correctly, new HSI is a kit and includes a bracket.

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tehDorf

Okay, that makes sense. Thank you for your help!