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Old 04-13-2012, 12:36 AM   #1
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A bryant HSI problem


Hey guys
I'm looking at a Bryant 80% with a 34 code. The inducer runs, the valve gets powered and opens but HSI doesn't get powered. Furnace can be fired, will run normally if manually ignited with a lighter and doesn't create any more fault codes untill the next heating cycle when the HSI doesn't fire up again. All components will operate through the board test sequence except the HSI. The connections at the board feeding the HSI only read around 4 volts. HSI ohms out OK.
Could it be anything other than a faulty board?

It's a $275.00 part for a friend with no dough so I'm second guessing myself.


Last edited by Jano; 04-13-2012 at 12:40 AM.
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Old 04-13-2012, 04:40 AM   #2
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A bryant HSI problem


If everything works in test mode except the HSI, nd the HSI ohms out less then 100 ohms, its generally the board.

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Old 04-13-2012, 10:32 AM   #3
how
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A bryant HSI problem


Hey beenthere
Don't quite get your "exception" reasoning with Jano's post..

The connections at the board feeding the HSI only read around 4 volts.

The only way I can measure the HSI volt output at a board is to pull the HSI board plug to access the pins. With the HSI out of the system, how can it affect the bad board output.
Regardless of the HSI being possibly bad, the board has already proved itself as bad when taking the rest of her post into account.

Am I missing something?

Last edited by how; 04-13-2012 at 10:36 AM.
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Old 04-13-2012, 03:53 PM   #4
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A bryant HSI problem


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Originally Posted by how View Post
Hey beenthere
Don't quite get your "exception" reasoning with Jano's post..

The connections at the board feeding the HSI only read around 4 volts.

The only way I can measure the HSI volt output at a board is to pull the HSI board plug to access the pins. With the HSI out of the system, how can it affect the bad board output.
Regardless of the HSI being possibly bad, the board has already proved itself as bad when taking the rest of her post into account.

Am I missing something?
I think you need to read what i wrote a couple more times.

let me rephrase it.

Since everything but the HSI works in test mode, and if the HSI itself ohms out at less then 100 ohms, then its probably just a bad board.






I've had techs in the past that told me they only had 75, or 30 volts coming out of the board for the HSI. So they replace it, and then the new board burned up cause they didn't see the frayed wire of the HSI that was grounding out.
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