Trane XL80 Controller Fail

I have a Trane XL80 that tries to heat but sometimes fails with a call for heat, but no flame detected. It is not the flame detector as the flame is not there. It turns on the gas, but the ignitor never gets hot. I replaced the ignitor to no avail. I don't want to replace the control board, around $160, without making sure it has to be done. The control board was changed out when the furnace was a little less than two years old by a technecian as it was under warranty. I thought then I might be in for many years of trouble with this furnace... Isn't there a reliable check to verify which part is bad? Can't I repair or improve/modify the board to work more reliably? What do you reccomend?
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__!__ -----o----- " " fix-it dad
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I have a Trane XL80 that tries to heat but sometimes fails with a call for heat, but no flame detected. It is not the flame detector as the flame is not there. It turns on the gas, but the ignitor never gets hot. I replaced the ignitor to no avail. I don't want to replace the control board, around $160, without making sure it has to be done. The control board was changed out when the furnace was a little less than two years old by a technecian as it was under warranty. I thought then I might be in for many years of trouble with this furnace... Isn't there a reliable check to verify which part is bad? Can't I repair or improve/modify the board to work more reliably? What do you reccomend?
-------------------------------------
__!__ -----o----- " " fix-it dad
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I am not an expert. I will of course counsel you to get a professional. The heating system is gas and that can kill you if things go wrong.
with that said. email support for you system maker. Ask for schematics and all service bulletin's. Also ask about repair records for you serial number. \ Once you have all of that, you should be able to figure out where the issues are. I suspect your correct that the control board is bad. But why is the question and can you fix it. with schematics and time, I think that any system can be understood and thus repaired. its just a matter of spending the time to become educated as to this particular "board" and or control system.
again, I urge you to find a contractor and have it checked out by a pro!!!!!!!! the dangers of diy are overwhelming.

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ok, not to start a big argument...
The bottom line is that it is similar to rocket science. You have logic circuits controlling all sorts of inputs and outputs. These control circuits are fairly basic, if you have electronics experience. The systems that are under the control of the logic circuits are also fairly simple, but, the cost of a failure could be a very bad situation. for instance, a runaway furnace that does not shut off and has a melt down. Or a back feed of combusted gasses into the living area of a house, at night due to any number of issues,,,,, etc etc etc.... so I stand by my original statement. Yes it can be fixed with the proper time and level of understanding, but the fix is better to be done by a trained professional, due to the possibility of a mistake that could be hazardous to life and limb...
and with that I bow out of this thread.

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greynom wrote:

If you don't have an ability to trounle-shoot logic circuitry, hot gunnin method won't lead you any where. FDo you have a impke multi- meter? Even a O'scope? are you saying ignitor does not get power?
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Could be the board, could be a bad safety, could be a sensor going bad, could just be a flaky connection somewhere. Intermittent problems are a bitch to find unless the symptoms are there when the tech is. Best bet is to call a competent tech (not the cheapest). As far as modifying the board, maybe you should apply for an engineering job at Emerson. FWIW, those few of us who are techs that *can* troubleshoot and repair the board, its not worth our time or your money to mess with them.
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