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Is there a code saying open limit?
It would be easier verbally but the site prohibits email and phone in order to protect customer privacy.
Now....the only time the unit has no light lit is when there is no power to the control. Blinking and steady lit are the normal oprations and faults.
Since you have no light it leads me to believe no power is supplied to the control.
This can be in the power switch
The blower door safety switch
If you had a 3 blink code for example it would say control has power but limit switch is open.
Here I think we need to back up and find where the 115v power is off.
There are 2 different types.
1) the switches are small round recessed around the bnurner box area. There is a small button in center. Pressing the button resets if tripped.
2) on the front wall behind gas pipe and valve is a flat switch directly on the fron wall. All you see is the flat plate and 2 wires attached. The switch is inside the furnace and not visable. This is an auto reset. It should reset itself...but if stuck open...tap the switch 4-5 times and retry unit. If switch does not close it will need to be replaced.
To test, remove the 2 wires and touch direct together thus bypassing the switch.
The xe90 has a burner area where the flame happens. It is on the perimetr of this burner area that the roll out switch would be.
Here ia picture of the 2 switches. The 2 outer ones are limits..the center is roll out with reset button
I just verified the control. The light is on constant when powered. The following is the fault code arrangement.
SYSTEM LOCKOUT FEATURES
When system lockout occurs, the gas valve is de-energized, the
circulator blower is energized at heat speed, and, if flame is
sensed, the inducer blower is energized. The diagnostic indicator
light will flash or glow continuously to indicate system status.
(System lockout will never override the precautionary features.)
If the sensed failure is in the system (external to the control), the
LED will flash in the following flash-pause sequences to indicate
failure status (each flash will last approximately 0.25 seconds,
and each pause will last approximately 2 seconds).
1 flash, then pause System lockout
2 flashes, then pause Pressure switch stuck closed
3 flashes, then pause Pressure switch stuck open
4 flashes, then pause Open limit switch
5 flashes, then pause Open rollout switch
6 flashes, then pause 115 Volt AC power reversed/Improper
7 flashes, then pause Low flame sense signal
Continuous flashing Flame has been sensed when
(no pause) no flame should be present (no
call for heat)
The LED will also flash once at power-up.
This is the limit directly under the burner box
The issue is till - the control will always be lit with power to it. Maybe a wire is off, pulled etc. But I assure you the control will be lit with power to it. The limit is as shown above. It just has shorter ends than previous picture. This part and information came directly from Trane TUC080 parts list.
I will opt out so the others can have a look for you.
I wish you luck.
Hello, My name is Lew and I will try to assist you along with my capable colleagues.Frequently, there is a float switch located in the secondary drain pan under the furnace(on the outside) that is responsible for breaking the control circuit in the event of condensate water overflow.The condensate pump (if present) also has an overflow float switch (integrally mounted).(For whatever reason it opens), It has the ability to stop the furnace/A/C process so that more water is not produced. Let's look for a pump that has been left un-plugged from the outlet (from when the plumber used his saw/drop light). Perhaps he accidentally kicked the float, affecting it's sensitive adjustment (if exposed on the outside of the catch pan) and breaking the low voltage control circuit. Also if the outlet is GFCI protected (push/test type) it could do the same thing. These may be more likely happenings and fits with your description of: ("working fine yesterday"). Be sure you replace the door panel before you try to start the furnace again.I hope this information helps you locate the problem.If so, I ask that You ACCEPT/BONUS my answers and provide POSITIVE feedbackfor my efforts, as You see fit. I will still be available to answer your questions if you need me further.Best of Luck & Thank You...Lew