Something stoped these Tranes
February 12, 2011 8:15 AM   Subscribe

I have 2 Trane XV 90 furnaces in my house the upstairs one has been unused for the season and is now not igniting. The downstairs unit has been running fine but it appears the blower motor is not coming on.

The downstairs unit is giving me an open limit switch error (4 blinks) I've found that it is the limit switch that is below the burner NOT the one with the little red reset button that is closest to the "flame window" the other one that is mounted against the wall of what I assume is heat exchanger. The burners ignite the exhaust fan runs like it should then after awhile the limit switch opens and the blower has not turned on.

The upstairs furnace is mainly used in the summertime for AC I went to turn it on and it will not ignite and comes back after a few try's with a 2 blink error code (system lock out) then the blower will come on and it will just run with no heat. I bled the gas line as it had been unconnected for a while with no luck. looking in the flame window I don't see anything that makes me believe that it is actually trying to ignite no glow before it lights like on the other furnace. Any help getting either of these furnaces at least blowing some heat to day would be appreciated.
posted by jmsta to Home & Garden (2 answers total)
Response by poster: Ok I confirmed the problem and was able to get the upstairs furnace lit and running. The ignitor appears to be bad. lighting it with a match got it up and running until it kicks off at least.
posted by jmsta at 8:48 AM on February 12, 2011

Wow, the silence is deafening!

I don't know the unit you mentioned, but do troubleshoot a lot of things.

You have a big advantage in that you have two units of the same type that fail in different fashions. You should be able to mix and match parts to get one working, provided you are comfortable with moving parts around, etc.

General warnings and observations:

Power off (via breaker panel!) when you are hosing around moving parts.
Generally, don't screw with gas. Prevent explosions where possible!
The BEST way to tshoot is to verify the problem, make it vanish, then return, then vanish.
At that point, you'll know you have conclusively identified it.
Connectors are 90% of electronic problems.

Trane is quality hardware. I'm surprised you have two failures and a little surprised you have one.
posted by FauxScot at 4:45 AM on February 13, 2011

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