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ECM blower motor issue

charliechicago Member Posts: 130
Hello to all,
I have an ECM motor (not X13) that when in cooling mode blows fine but with just a call for the fan it spins very slow. I spoke with Trane support and they said that since the board is giving 12 flashes to indicate 1200 cfm (it's a three ton) then the board is ok it must be the motor. But doesn't the board get the signal for fan in both cases from G on the tstat? So wouldn't the same thing happen in both cases? Any ideas? Thanks, Michael.


  • heathead
    heathead Member Posts: 234
    Generally with and ECM motor in fan speed it runs slower than in cooling speed.
  • charliechicago
    charliechicago Member Posts: 130
    Thanks for your input.
    The owner says he used to be able to feel the air blowing when he does the dishes and he’s not the type to make things up. Also it blows so little you get almost no air flow from the register.
    HVACNUT Member Posts: 5,832
    edited May 2018
    Not sure about Trane but some manufacturers have dip switches to set fan speed for fan only, dehumidification, etc.
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557
    Typically, G runs the blower at half speed just for air circulation. A call for cooling energizes Y and brings the blower to high speed. The board sends a signal to the ECM control module which in turn runs the motor.

    Conceivably the control module could be the issue, though ecms tend to work or not.