Trane Blower Motor will not shut off

[tbrinegar]

I have a Trane Heat Pump set up the Air handler Model number is 2TWR3042A100AA 3.5 ton. It has a variable speed motor ECM 2.3. About a month ago I noticed that the Blower will continue to run on a low speed all the time. I have a Pretty much identical unit for upstairs. In the process of trying to isolate the problem I have swapped parts to try to replicate the problem on the upstairs unit. I have swapped the Module, Electronic fan control, the ECM 2.3 that is on the end of the motor and I have swapped the indoor thermostat. I have not been able to get the problem to move in order to isolate. Is there anything else I can try. Thanks

[nomadpeo]

good shot duke. are the thermostats the same * did you swap them *