Ignitor Problem no heat

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Old 10-12-13, 06:59 AM
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Ignitor Problem no heat

Hi all,

We have a 5 year old Trane XV95 natural gas furnace which doesn't provide heat. The red LED flashes 6 times indicating a faulty Ignitor. Here is the sequence of what happens:

- if power is not cut off to the furnace the fan stay on, blowing cold air regardless of thermostat fan and heat/cold setting.
- after power is turned on the inducer motor turns on for a few seconds, turns off then the fan starts and stays on. This behavior is the same regardless of thermostat setting for fan on/auto and heat/cold/off.
- replaced thermostat with a new one, no change
- replaced Ignitor with a new one, no change
- fan stops blowing and LED stops red flashes when I remove the Ignitor wires and thermostat heat setting is off
It is perplexing to say the least. Would it be a defective control board?
 
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Old 10-12-13, 07:33 AM
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Can you provide the model number for your furnace? XV95 is a series not a model number. According to a data sheet I found 6 flashes is for reversed polarity or a grounding issue. It could be a bad control board. Once you provide the model number a more definitive answer can be given. After inducer motor starts does the ignitor glow? Here is a link to an installer's guide for the XV95: http://aplusair.com/pdf/XV95%20Insta...n%20Manual.pdf and another link to the service facts which lists other possible causes for six flashes including faulty ignitor triac and low voltage.

http://www.butcherdistributors.com/I...ce%20facts.pdf
 

Last edited by firedawgsatx; 10-12-13 at 08:07 AM.
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Old 10-12-13, 08:08 AM
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Thanks Firedawgsatx , the Model is TUH2B060A9V3VAA, Ignitor doesn't glow and inducer stays on for about 5 seconds before it shuts off and the fan comes on.

I will check for an inducer reset button. How can I check the furnace is properly grounded with a voltmeter?

Also isn't the fan behavior strange?
 
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Old 10-12-13, 08:34 AM
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It appears you are not getting voltage to your ignitor. Can you check voltage from inducer motor to the terminals on the control board while the inducer motor is spinning?
 
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Old 10-12-13, 12:02 PM
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While inducer is running there is 30 volts on each of 3 leads, fourth one is ground, all go to zero when inducer stops.

There is a constant 120 volt at the Ignitor lead at all times.

There is no reset button on the inducer

Ground seems ok between chassis, control board and house water pipe.
 
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Old 10-12-13, 01:39 PM
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The sequence of operation should be the induce draft motor energizes, purges, ignitor glows and then gas valve opens. Since you stated you have 120V to the ignitor leads the ignitor should glow. Possibly the new ignitor is defective. Have you confirmed the ignitor leads are on the correct connections? When you say 120V was at the ignitor leads was that reading taken on the control board where the ignitor leads connect? You can ohm the ignitor to see if it is within specs. You would have to know what the ohms range is for the ignitor. Typically they are in the 40-90 ohms range. Do you have make/model number of the ignitor?
 

Last edited by firedawgsatx; 10-12-13 at 03:02 PM.
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Old 10-12-13, 04:42 PM
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I find your description of the operation of your furnace to be ambiguous.

There are two fans. A small fan above the burners which circulates combustion air through the furnace called the inducer motor and the fan that circulates heat through the furnace to the house.

Describe the sequence of events that occurs when you turn up the thermostat in order and in detail.
 
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Old 10-12-13, 08:53 PM
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Resolved!

Thanks to the experts for your help. I am embarrassed to say I reversed the polarity inside the furnace and all is well. I had reversed the polarity at the outside junction box but apparently the wrong circuit. :-(
 
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Old 10-12-13, 09:06 PM
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Glad to hear you are back up and running. Thanks for letting us know the outcome.
 
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