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quovadis 12-16-2008 09:34 AM

Problem with Trane gas furnace
:eek:I have Trane TUJ100A960A1 gas furnace with following
problem (I will describe furnace behavior as I have seen it).

Early in the morning Iíll typically move the thermostat up few
degrees to get furnace to kick in. Letís say the room temperature
is 64 degrees. Iíll set thermostat to 68.
Furnace kicks in, runs for few minutes and after the temperature
goes up approx 1 degree (65), it kicks out. Fan blower motor
runs short while longer then it stops. Thermostat displays ďtemporaryĒ.
Now the furnace just sits like his for a long time. It does not run.
If I move thermostat to letís say, 69 it gets ignored.

If I bring it down bellow current room temperature, down to 64
Iíll hear a little click on the thermostat. Now, if I move it back up
to 68, Iíll hear the heat induction motor kick in at the furnace,
Iíll se the igniter light up, Iíll hear the gas hiss, and get ignited.
Seconds later Iíll hear thermostat klick off although no one
touched it, and the burners shut off. Blower motor kick in,
and runs for few minutes, the it too, shuts off.

Then for the rest of the day, nothing will change.

Thermostat will click every few minutes calling for heat,
yet furnace will not respond. To correct this situation I have to
turn the thermostat off, and cut A/C power to the furnace,
wait few minutes, and turn everything back on, all may be well
for a day or two. Then back to the same olí, same olí.

I have checked the following to be good:
Induction motor, its switch, vent tube, exhaust flue,
Igniter, and flame sensor.
There are no loose connections. Filter is clean.
I assume something sends the furnace into "lock out" mode,
but what???

hvaclover 12-16-2008 09:52 AM

Sounds to me like your programmable stat is not working right.

Have you tried pulling the batteries and reprogramming it? If that does not cure the problem than the micro switch that makes and passes power to activate furnace is starting to fail.

quovadis 12-16-2008 01:03 PM

It's not T-stat
I swapped T-stat with identical one, and exact problem still exists.
I can't understand that once furnace runs, it only brings up temp by 1 degree, then shuts off. Never more than 1...

beenthere 12-16-2008 03:39 PM

Check your air filter.

quovadis 12-16-2008 03:56 PM

Filter is new....and the right kind.

beenthere 12-16-2008 04:03 PM


How do you know its not the pressure switch, or inducer causing the problem.
How did you measure the pressure.

Did you look for a fault code.

hvaclover 12-16-2008 04:05 PM

well Gee, if you already checked that other stuff (and you knew how to do it correctly) then why do you need us Pros?:huh: help me out here I cause I really don't get it.:whistling2:

hvaclover 12-16-2008 04:08 PM


Originally Posted by beenthere (Post 198946)

How do you know its not the pressure switch, or inducer causing the problem.
How did you measure the pressure.

Did you look for a fault code.

Didn't ya read the first post Been? He Already checked that stuff and KNOWS it's good. Beyond me why he's even askin' for help.

quovadis 12-16-2008 06:03 PM

Few more hints...
If the furnace is cold, it will fire every time, first time.
As it gets warmer, it has trouble restarting. It appears igniter doesn't get bright enough on restarts. Doesn't light the gas, and the system goes into lockout. I'm guessing igniter gets weakened by the flames.

This system doesn't show fault codes.

Please refrain from making sarcastic remarks.
I know you are the experts. I'm not. This is why I'm here.
Thanks in advance.

beenthere 12-16-2008 06:07 PM

Does your model have the WR ignition module.
Bout 4.5 by 3.75

If so, check wire connections.

quovadis 12-17-2008 07:54 AM

Control module is W.R. 50A52-101.
Connections were cleaned, and wires checked.
Problem still there....
p.s. Does anyone know of a web site that lists igniters for
Trane furnaces by model number.


SKIP4661 12-17-2008 08:05 PM

What's the resistance reading of the ignitor?

spiritseeker 12-18-2008 08:11 PM

Comfortmaker blower will not come on in auto mode
Hi, when I turn up the thermostat the furnace ignites but blower does not come on, when I manually turn the thermostat to "fan" the blower will come on. Can anyone tell me what the problem might be?

beenthere 12-18-2008 08:15 PM

Could be the motor.
Could be the control board.

spiritseeker 12-18-2008 08:19 PM

Do you think it could be the motor when the fan works manually just not on auto?

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