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Old 12-31-2009, 12:43 AM   #1
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Trane XR90, LED flashes 2 times for error


Trane XR90, LED flashes 2 times (flash-flash ---long pause--- flash-flash).

It is recycling itself, or failing to recycle...

So then the blower continues to blow air...but not warm air. No heat. Just a running fan, blowing air.

At times, I have "reset" it by powering the furnace off/on 2 times within 30 seconds as the manual advises. (Powering off at the breaker box.) This has cleared the problem many times for 30-40 days.

And then, it happens again. Same flash-flash. Blower blowing with no heat - just air.

Sometimes the "reset" technique mentioned above will not work at all (for a day or two). Then, all of a sudden, the "reset" works and heat is blowing again.

Any ideas?

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Old 12-31-2009, 01:38 AM   #2
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Trane XR90, LED flashes 2 times for error


From what you described, it sounds like it could be the high limit, but these things are hard to diagnose over the internet. Your best bet would be to see what the flashes mean by looking on the labels on the furnace door. The error codes are usually quick flashes followed by longer flashes, and also usually double digit to avoid confusion.

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Old 12-31-2009, 09:29 AM   #3
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Trane XR90, LED flashes 2 times for error


Quote:
Originally Posted by James35 View Post
Trane XR90, LED flashes 2 times (flash-flash ---long pause--- flash-flash).


It is recycling itself, or failing to recycle...

So then the blower continues to blow air...but not warm air. No heat. Just a running fan, blowing air.

At times, I have "reset" it by powering the furnace off/on 2 times within 30 seconds as the manual advises. (Powering off at the breaker box.) This has cleared the problem many times for 30-40 days.

And then, it happens again. Same flash-flash. Blower blowing with no heat - just air.

Sometimes the "reset" technique mentioned above will not work at all (for a day or two). Then, all of a sudden, the "reset" works and heat is blowing again.

Any ideas?
James:


A 2 flash code means that the furnace is in a 'hard' lockout. This happens after 3 trials for ignition. You haven't listed the model and serial number of the furnace so it is hard to get real specific. XR90 is the family of 90+% furnace of Trance, but the model will be something like TUX... or TUY....ALSO, is it natural gas or LP?

1. To reset it in from a lock out you have to interrupt the power to the board for several seconds, which it sounds like you have done in the past. If it is a nuisance trip this will take care of it.

2. Some causes of lockout caused by failure to ignite can be an igniter that is getting weak (depending on the model number of the furnace whether it uses a silicon carbide or silicon nitrite igniter it should ohm out at 40-80 ohms cold (SC) and between 11-17 ohms for the (SN)); poor air/gas mixture (this can also happen during extremely cold weather when the gas company injects propane into the natural gas lines to keep the gas pressure up, or they haven't done it soon enough); the flame sensor may also be getting old or corroded up. These are some causes on intial start up. If it fails after it runs for some time there may be a crack in the heat exchanger that expands after it runs for some time and if it blows on the flame it can lift it off the flame sensor causing it to shut down.

3. And the reason the blower keeps running after the flame fails is to alert you that something is wrong with the furnace.

4. You mentioned that sometimes resetting doesn't work???? This could mean that the main board is bad OR you have a loose wire somewhere and when you are moving wires a connection is remade. Sometimes the connections become corroded or pitted so make sure that all the connections are clean and solid. After power down and up, does it try to light? What I mean does the igniter glow and the gas valve attempt to open? (Something else to consider - is the gas valve sticking?)
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Old 01-05-2010, 02:52 PM   #4
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Trane XR90, LED flashes 2 times for error


This sounds like a problem I am having with an older American Standard furnace. The board will tell you if you have a flame sensor, air pressure, or limit switch failure. The gas valve doesn't seem to want to stay open, it clicks on and off after a time, the control board is brand new and the voltage to the gas valve is constant when this happens. The flame is a nice blue not a bit of orange, so I don't think it is too rich. It will run anywhere from a minute to five minutes when this happens.
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Old 01-05-2010, 03:48 PM   #5
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Trane XR90, LED flashes 2 times for error


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Originally Posted by H. Phillips View Post
This sounds like a problem I am having with an older American Standard furnace. The board will tell you if you have a flame sensor, air pressure, or limit switch failure. The gas valve doesn't seem to want to stay open, it clicks on and off after a time, the control board is brand new and the voltage to the gas valve is constant when this happens. The flame is a nice blue not a bit of orange, so I don't think it is too rich. It will run anywhere from a minute to five minutes when this happens.
If you have constant 24 volts to the gas valve and it's turning off and on the the valve is bad.
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Old 01-05-2010, 04:13 PM   #6
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Trane XR90, LED flashes 2 times for error


If you have constant 24 volts to the gas valve and it's turning off and on the the valve is bad.

My head says this is so. But my stingy heart says "Are you sure! Those gas valves are expensive!"
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Old 01-05-2010, 04:55 PM   #7
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Trane XR90, LED flashes 2 times for error


Yes, if you have 24 volts to the gas valve and it shuts off the valve is bad. You say it runs for 1-5 minutes and then shuts off, so also be sure you are not losing flame contact with the flame sensor. It only takes a millisecond of loss contact with it to have the valve close. Loss of contact can be caused by the flame being blowen or lifted off byair leakage from a cracked heat exchanger or poor flame distribution if the burners are starting to get dirty. Just some things to check.
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Old 01-05-2010, 11:05 PM   #8
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Trane XR90, LED flashes 2 times for error


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Originally Posted by Final Final View Post
Yes, if you have 24 volts to the gas valve and it shuts off the valve is bad. You say it runs for 1-5 minutes and then shuts off, so also be sure you are not losing flame contact with the flame sensor. It only takes a millisecond of loss contact with it to have the valve close. Loss of contact can be caused by the flame being blowen or lifted off byair leakage from a cracked heat exchanger or poor flame distribution if the burners are starting to get dirty. Just some things to check.
The gas valve is giving very audible clicks. The flame appears to be very steady with no drafts. The unit was cleaned last year. Being a dual fuel unit it doesn't run that much except in extreme weather and morning warm up. If the flame sensor was telling the control board there is no flame and the board was turning the valve off, then there would be a loss of voltage to the valve. Or would it be so fast I cannot see it on my digital voltmeter?

Also would the unit not give a flame sensor failure reading instead of recycle time out?
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Old 01-06-2010, 06:36 AM   #9
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Trane XR90, LED flashes 2 times for error


Check your vent system.
Pressure switch is probably opening up and closing very quickly.
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Old 01-06-2010, 07:08 AM   #10
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Trane XR90, LED flashes 2 times for error


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Check your vent system.
Pressure switch is probably opening up and closing very quickly.
It didn't when tapped. Also the IFC should send a low pressure warning. And again I would expect the voltage to drop out.
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Old 01-06-2010, 07:18 AM   #11
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Trane XR90, LED flashes 2 times for error


Those pressure switches can open and close faster then your meter can detect.
And the board won't report it as a pressure switch failure.
Generally comes back as a flame failure. Or a lock out from X retries.

Digital meters are not fast enough to catch it.

A manometer will though.
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Old 01-06-2010, 10:22 AM   #12
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Trane XR90, LED flashes 2 times for error


If it is definite audible click that is the solenoid valve in gas valve opening and closing and it sure sounds like loss of power to valve.

Like it has been said, it is tough to trouble shoot over the internet; we are just giving you possible scenarios...this is definitely one of those 'nuisance' problems that are a little tough to catch. From a service tech perspective it is always better to have a 'catastrophic' breakdown; much easier to diagnose and repair..Now it is a little like playing detective and eliminating all the possibilities one at a time until you find out which part is causing the issues. I hate being a parts changer and replacing everything until it works...I'm sure you don't want to be one either....plus it can get expensive.

One of those safeties (air switch, flame senser, gas valve, transformer (are you getting a good 24-27 volts from the secondary?); high limit; inducer motor, etc). Also be sure you have a good solid (earthen) ground to the furnace. Check between the white 'neutral' wire going to the furnace and the green 'ground' wire. You theoretically should have '0' volts, anything over 10-12 volts can cause you trouble with the board. At the same time make sure all your electrical connections are tight; a loose connection caused by vibration can sometimes cause it to act up.

You say you are only getting a 2 flash fault code; which means a hard lockout, so this only happens after a 3 trial for ignition failure.....if one of the other safeties is opening again theoretically you should be seeing a different fault code. I don't know what model number of furnace you have so I can't give you the different codes; depending on which one it is you can have up 7-9 diagnostic codes.....make sure it is not some other code than 2.
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Old 10-18-2010, 11:42 AM   #13
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Trane XR90, LED flashes 2 times for error


I know that this thread is a little old but I have been having the same problems with my trane xr90 furnace. it tries to cycle on three times, doesn't stay on, and then the fan blows cold air until someone notices. the error code is two blinking lights.

I pulled the front panels off and checked the ignitor (silicon nitrate), which seemed to be in order (13.5 ohms resistance). I watched as the furnace started and the flame came on every time from 8-20 seconds and then went out. I took out the flame sensor and scrubbed it a bit (it had just a little corrosion on it) and put it back in but it didn't seem to change anything. I also cleaned the intake/vent outside since I noticed that it had a few cobwebs in it, but it didn't help.

My gut feeling is that it's the flame sensor, but I really don't know that much about furnaces. Anyone have any thoughts?

Thanks.

Model# TUX080C942D3

Ps - I forgot to add that I can hear an audible click a second or two before the flame goes out. I am not sure if that is part of the normal cycle of shutting down the flame or if that is the valve switch losing power for another reason.

Last edited by theob; 10-18-2010 at 11:44 AM.
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Old 10-18-2010, 05:15 PM   #14
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Trane XR90, LED flashes 2 times for error


Did you check the exhaust pipe.
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Old 10-19-2010, 01:07 AM   #15
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Trane XR90, LED flashes 2 times for error


I checked the exhaust pipe on the outside of the house, but not inside the furnace. I did not want to disassemble the furnace too much without a service manual or some sort of know-how (i have nothing other than common sense to go by right now).

However, on closer inspection, I found out that the glow from the window actually wasn't from a flame being lit but actually from the ignitor itself. There is no flame, just the ignitor coming on and off. I can't believe I didn't notice that in the beginning.

Even though I tested the resistance of the ignitor and it seemed ok at 13.5 ohms resistance, I wondering if it could possibly be that. What else could it be?

Thanks for the reply.

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