# Trane xe90 has stopped at the station



## kurgen (Jan 22, 2013)

Folks,

My unit is an XE90 model tux080c942c3, serial z2833rt7g. I have had annual issues with this baby, but this year, it is not cooperating. When switched on, the exhaust fan starts up and the ignitor (new) starts to heat (I know this cause I burnt my finger on it), but before it can get to glowing, the exhaust fan kicks off and the unit clicks into the circulator fan clearing out the system. I am getting nine blinks on the unit (check ignitor). I ran a snake up the exhaust pipe and checked the roof vent as well as opened the pipe in the attic. It appears clear. I also gave the flame sensor a quick sanding to clean it off. Any thoughts? Could the exhaust fan pressure sensor be bad?

Thanks


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## Wuzzat? (Jan 22, 2013)

For $100 in equipment you can probably make all the necessary measurements to isolate the problem to a single component.  

Think of it as tuition for an HVAC course.


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## kurgen (Jan 22, 2013)

Sounds like a good plan.  Problem is Trane does not provide a ton of detail on voltages, resistance or anything else for that matter, including a parts list.  At least for a car you can get a detailed manual.


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## kok328 (Jan 22, 2013)

If 9 blinks is "check ignitor" then check it.  Do not touch the ignitor with your fingers as the oil on you skin will create a hot spot on the ignitor surface (similar problem as the newer automotive headlight bulbs).  Check the ignitor to see if it ohms out at 100 or less.  Anything over that and the ignitor is worn out.  It should glow redish/orange when heating up, if not then that may be your problem.  Good luck on finding a replacement, they aren't easy to come by without a mechanical license.  You may be able to find a universal replacement from someplace like Graingers.


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## Wuzzat? (Jan 22, 2013)

http://www.grainger.com/Grainger/ecatalog/N-1z0du0f


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## keepinitcool (Jan 22, 2013)

Get a glowfly. Pretty universal hot surface ignitor.


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## kurgen (Jan 23, 2013)

I found a new ignitor and put it in.  No change to the situation.  I am going to try replacing the flame sensor and the limit switch on the draft inducer fan to see if that is the issue.  I pulled the fan last evening and it would run when outside the housing, but with any back pressure (even when disconnected from the pipe and just sitting there with the air going half up the pipe) the fan would kick off as before.  I have seen the flame sensors around.  Any idea on finding the limit switch...or am I chasing the wrong car?


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## kurgen (Jan 23, 2013)

BTW, Thank KOK328.


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## Wuzzat? (Jan 23, 2013)

kurgen said:


> I found a new ignitor and put it in.  No change to the situation.



Bad Mojo?


Here is my generic DIY strategy which might have led you wrong in this case.

DIY or HAP (Hire A Pro)?
If in the unlikely case that HAP will cost you less than the part cost then HAP.  If HAP costs >10x or 100x the parts cost, take the gamble.
When is this decision a toss-up?

Here are numbers for an optimistic 10% chance that the part *will not* work, and for a pessimistic 50% that the part will work.

40	>enter parts cost PC in dollars
10	>enter likelihood in percent L of having to HAP after you buy the part
1000	>enter probable HAP in dollars
140	= your calc'd DIY cost CDIY = PC + HAP x L/100
	so choose DIY

40	>enter parts cost PC in dollars
50	>enter likelihood in percent L of having to HAP after you buy the part
200	>enter probable HAP in dollars
140	= your calc'd DIY cost CDIY = PC + HAP x L/100
	so choose DIY but with less assurance


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## kok328 (Jan 23, 2013)

Sorry to hear that the new ignitor didn't fix the problem but, I did mention to test it before replacing it.


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## Wuzzat? (Jan 23, 2013)

Mr. OP, at this point I recommend you decide ahead of time how much more money and time you are going to put into this before going the HAP route.

The money you spent on this part is a Sunk Cost and should not influence your next decision.

You should also test both the old part and the new part, but this particular part is probably pretty hardy.


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