DIY Home Improvement Forum banner

Problem with Trane gas furnace

11K views 17 replies 6 participants last post by  secure 
#1 ·
:eek:I have Trane TUJ100A960A1 gas furnace with following
problem (I will describe furnace behavior as I have seen it).

Early in the morning I’ll typically move the thermostat up few
degrees to get furnace to kick in. Let’s say the room temperature
is 64 degrees. I’ll 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 “temporary”.
Now the furnace just sits like his for a long time. It does not run.
If I move thermostat to let’s say, 69 it gets ignored.

If I bring it down bellow current room temperature, down to 64
I’ll hear a little click on the thermostat. Now, if I move it back up
to 68, I’ll hear the heat induction motor kick in at the furnace,
I’ll se the igniter light up, I’ll hear the gas hiss, and get ignited.
Seconds later I’ll 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 ol’, same ol’.

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???
 
See less See more
#2 ·
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.
 
#6 ·
Ok.

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.
 
#9 ·
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.

p.s.
Please refrain from making sarcastic remarks.
I know you are the experts. I'm not. This is why I'm here.
Thanks in advance.
:(
 
#16 ·
Could be either.
Many blowers run at one speed in auto, and another in "on".
So the speed winding used in auto could be bad, but not the speed winding used in "on".

Use a meter to see if your control board is supply power to both output terminals.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top