skeatus

The blower on my Trane xe90 is always running I set the the thermostat to off and it still runs. The only way I can get it to turn off is to shut the furnance off at the shutoff. I just replaced the circuit board just over a year ago. I read other forums and they say the the fan relay. I think that is integrated in my circuit board, but I am not sure. Please let me know where to go next.

kok328

Could be the thermostat is bad, thermostat wires are shorted or blower relay is stuck closed.
To narrow down the problem, disconnect the red thermostat wire inside the furnace and then turn the furnace back on w/the cover panels reinstalled.
If the blower comes on then the problem will be the blower relay.

skeatus

Removed red wireand blower did not come on. Does that mean my themostat?

hvactechfw

It means your stat or your wiring. Next step reinstall red wire to control board, then remove green wire from stat. Does blower shut off? If so then stat, if not then wiring is shorted.

skeatus

Ok took off green wire from stat and blower still ran. Where do i start to try and find short. I have wires coming from every where.

kok328

Looks like the thermostat wires may be shorted (red is touch green).
To confirm this disconnect both the green and red wire from each end (thermostat and furnace) and then check for continuity between them.
If continuity is present then you have a short. If not continuity then I'm not sure what the problem is.

skeatus

stat wires are not crossed. Anyone have any other ideas?

kok328

run it by "paul52446m", he's up in Houghton Lake.

How did you determine that the stat wires are not crossed ?

skeatus

I removed the stat from the furnance and the blower still ran

kok328

When you removed the red stat wire from inside the furnace, you reported back that the blower did not come on.
When you disconnected the green wire from the stat, you reported that the blower did come on and stayed on.
You have not performed a continuity test on the red & green wires to determine if the wires are shorted together.
I think you'll find that you do have continuity between the red and green stat wires.
Disconnect the red & green stat wires from inside the furnace and from the stat and perform a continuity test with a meter.
Otherwise, hook the stat up to the furnace using a few feet of new stat wire and you'll find that your problem goes away. In which case all you need to do is replace your existing stat wires.