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Trane XB-80 Error Code 4

UglyJoe's Avatar

Join Date: Dec 2010
Posts: 2

12-09-10, 12:48 PM   #1 (permalink)  
Trane XB-80 Error Code 4

I have a trane XB-80 that about 4-5 years old. I am getting a a '4 rapid flash' signal that indicate a upper limit switch error. In trouble shooting, I have replaced the controller card, and temporary jumper-ed across the limit switch (the one slightly above the burner assembly.) Following the schematic, I have also ohm'ed across the in-line fuses and see no open there.

So my question is:
exactly where is the second limit switch located at, behind the small blower assembly? or on/near the main (larger) blower motor that is in-line with the airflow?

How do I reach that switch?

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UglyJoe's Avatar

Join Date: Dec 2010
Posts: 2

12-09-10, 02:01 PM   #2 (permalink)  
Omg,omg !!!! It worked !!!

scarfed from another fixit board... it worked for a xr.. mine is a xb...
(even same reason, stopped working after a power failure)

utah-ike wrote at 2007-12-03 16:31:3

I ran into this same thing 3 days ago. It seems silly that they do not explain this in the users manual...I guess it is a conspiracy to get you to call a contractor.

This is VERY common on this series of heaters. What has happened is the Overheat circuit has been tripped. Ours tripped when the power went out during a preheat cycle of the heater. It does not take much to trip these things.

This fix is going to sound silly and almost too simple. You will be frustrated that you spent the night in the cold over such a silly fix...I did!

OK...to fix, remove the front panel from the furnace. You will see a 2 inch by 3 inch circuit board with two wires attached to it. This is located on the firewall right behind the fuel shutoff valve. Take a screwdriver and place the tip on the top screw on the circuit board listed above. Take another screwdriver and give the other screwdriver 3 good solid knocks. Put everything back together, turn your furnace on and enjoy the heat.

The 3 knocks make the sensor switch fall back into place, allowing the circuit to close.

Pretty dumb huh? Wouldn't it have been easier for Trane to put a little button on the circuit labeled "RESET"? Man I hate product designers...they should be forced to use this stuff for a year in their own home.

Now, that being said...If you continue to trip the circuit, or you have no explanation why the circuit tripped..you should really call a tech to come and examine the airflow for possible obstructions.

Good luck.

I am definitely a happy camper!
Thanks, mr utah, ike and whoever provided the link from here...

It worked just fine!, even as such, I plan on replacing that sensor.
(dont understand why it ohm'ed out fine earlier, though)

Great board, great ideas, and great help!

S-fahan's Avatar

Join Date: Feb 2012
Posts: 1

02-19-12, 10:56 AM   #3 (permalink)  
Trane Xb-80 Error Code 4

Thank you,UglyJoe for your advice, I had the exact same problem as you described, and i did exactly what you suggested, and it was fixed! I didn't have to pay a repair man, and i didn't have to wait. Thank you,and you are great!
Here is another problem I have with my A/C though, I have a 4 tonTraine A/C unit that has a leak, but I cannot find the leak, I have a leak finder but it didn't find any leaks and it leaks pretty bad, about 10 pounds a year. Do you think you can help please?
-Thanks S-fahan

hvactechfw's Avatar

Join Date: Jan 2011
Posts: 6,245

02-19-12, 11:11 AM   #4 (permalink)  

We can not help you find a leak on a refrigerant system, this must be done by a EPA certified technician.

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