Need Help with furnace Trane XE 78

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  #1  
Old 01-18-09, 07:07 PM
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Need Help with furnace Trane XE 78

I have a furnace Trane XE 78, White Rordgers(model:50A50-406) and I have a couple questions with this furnace. I am really new to this, and try to fix my furnace myself.

1. What type is my furnace like standing pilot or intermittent pilot, or something ele.

I will also include picture, so you can see better.

My furnace has this problem, it blowing cold air, and the only way that i can fix it is turn power off and then on again. IT will fix for couple minutes and then blowing cold air agian.

can anyone tell me where should I start to check my furnace. I am live in Minnesota and 2 days ago was -20. It is nightmare.






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Old 01-18-09, 07:35 PM
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The ignitiopn module you have is for a hotsurface ignition control system. That means that the gas is lit by an electrical ignitor that glows white hot to light the main burner.

You need to provide a better description of what is happening before we can provide any help.

Withe the fan cover in place and the burner cover removed, turn the thermostat down until the furnace shut off completely. Then turn the thermostat up and pay attention to the series of events that happen as the furnace tries to turn on. You may need to repeat this a few times until you see and hear what is going on and can report it here.

In general, when the thermostat turns on the inducer motor, the small black motor should turn on and come up to speed. The the hot surface ignitor should glow white hot for a minute or so, and then the gas should turn on and light off the burner.

How far in that sequence of events does your furnace get?
 
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Old 01-18-09, 07:49 PM
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Ok , I see it the fan is running, and I see flame ( blue fire) up for couple second than burner up next ( woup , woup sound) for couple second or minute, then fan still running but no more fire, it dark in the furnace, then flame come on again ( i can see again) next the burner up agian for couple second then the whole thing gone again( dark agian) no more flame, and it keep doing that.

Thanks for the fast reply , I see HOPE now.

the blue fire that I talk about look like this pic
 
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Old 01-18-09, 08:43 PM
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It sounds like the main burner is lighting, but the flame sensor on the left side of the furnace isn't detecting the burner ignition. If that happens, the main burne gas shuts off after a couple of seconds just as you describe.

Look for the flame sensor on the left side of the burner assembly. It's typically a rod of metal 3-4" long with a wire coming out the bottom going back to the ignition control module.

That rod can get covered with oxides that prevent the burner ignition from being detected. So you should remove the flame sensor and clean it with a wire brush and reinstall it.

I see a couple of organge wires going in to the left side of the furnace --- I don't know where they are going. Typically there is only one wire going to the flame sensor.

Anyway, give that a try if you can find that part. Usually it's pretty easy to get to and remove.
 
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Old 01-19-09, 05:59 PM
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Could also be a weak pilot not fully engulfing the flame sensor all the time - and that kills the flame. You can remove the entire intermittant pilot assembly and remove the pilot flame end and clean out the tiny orifice hole, to fix that.
 
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Old 01-19-09, 06:15 PM
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hix, really exciting and love to try all of your methods, but I couldn't do it right now. I have to go to work, and will come back home on Friday and my family doesn't know a thing about electronic.
I will try it on Friday night.
Thanks very much.
 
  #7  
Old 01-30-11, 07:53 PM
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Trane Furnace

I have the same furnace and can't even find a way to remove the panels to see if the piolit is still lit. There is no pilot light. It does it electronically

Is there a special trick to gettin the panels off?They just had to be forced up in order to create room to remove the lower panel.

Next we followed the manual's instructions to power cycle it, but it didnt' work.
 

Last edited by mshirk; 01-30-11 at 08:48 PM. Reason: Initial problem solved
  #8  
Old 01-30-11, 08:38 PM
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lift up on handle on burner door on upflow furnace (door with louvers) lift up on blower door on downflow furnace (solid door) take picture and post it if you cant figure it out http://forum.doityourself.com/humidi...st-photos.html
 
 

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