Trane xe90 Blower Motor Not Kicking in

Discussion in 'HVAC' started by Fitmiss, Nov 3, 2011.

  1. Nov 3, 2011 #1

    Fitmiss

    Fitmiss

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    I though my problem had to do with the new thermostat I installed but have now realized that the thermostat is working fine. Heat is coming out of the vents however I now realized that no hot air is ever being forced out of the vents thus the house is never reaching the setpoint temperature.

    I have made an appt. for someone to do a pre-season tune-up on the furnace and know they will ultimately diagnose the problem. In the interim, are there any suggestions as to what I can do to definitively diagnose and/or fix the problem?

    Heat is coming out of the vents. I've heard the fan work and have seen the flame light.

    I did notice that I have 4 flashing lights which has to do with the high limit. I'm guessing the thermostat is working too hard to reach the setpoint temperature.

    Anyone? Oh - if it is the blower motor, how much should I expect to pay for the repair?
     
  2. Nov 4, 2011 #2

    kok328

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    It just might be the blower motor but, the furnace would only run long enough before it trips the high limit switch. If it is the blower motor, you can expect to pay somewhere in the neighborhood of $250 for the motor, not including labor.
     
  3. Nov 4, 2011 #3

    Fitmiss

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    Is there possibly a fuse or breaker right on the unit that could have tripped? I've checked the main breaker box and the breaker for the unit is fine.
     
  4. Nov 4, 2011 #4

    paul52446m

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    If you lose you 24 volt power at the furnace, there is, on most electronic boards, a small plug in fuse like you use in a car, probably 3 amp. Paul
     
  5. Nov 5, 2011 #5

    Fitmiss

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    Where is this fuse located - anyone know? I'll also have a look on the schema.
     
  6. Nov 5, 2011 #6

    kok328

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    The fuse is located on the green circuit board. It's the blade style fuse used in automotive applications. However, I doubt the fuse is bad because your furnace is able to fire up to the point that heat is not being removed from the heat exchanger which in turn will cause the high-limit switch to shut down the furnace to prevent a melt-down.
     
  7. Nov 6, 2011 #7

    seawood

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    When was the last you replaced the air filters if they are pluged you will not have athe right of return air and will trip high limit and if it trips often it will stay open
     
  8. Nov 6, 2011 #8

    Fitmiss

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    I replaced the filter this week. Is there only 1?

    I had seen the 4 blinking lights and read on line that it was sometimes due to a dirty filter. Sure enough the filter was dirty so replaced it and the 4 flashing lights changed to a normal pattern. Still I did not get the forced air and then the 4 flashing lights started again.

    The worst symptom is no forced air so the house temperature never reaches setpoint.
     
  9. Nov 6, 2011 #9

    seawood

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    when the light is blinking 4 times is the main blower running is there forced air comming from vents if not it could be the control board or the blower motor you would need to test the blower motor by by passing the control board
     
  10. Nov 6, 2011 #10

    Fitmiss

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    The whole problem is there is no forced air coming through the vents. There is heat coming through but not forced air.
     
  11. Nov 6, 2011 #11

    seawood

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    then it is the main blower or the control board theyt some times short outn the contacts and will not let the blower run power the blower with jumper and see if it runs
     
  12. Nov 10, 2011 #12

    thanksagain

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    Hi, I'm new here and don't know how to post but Ive been reading this thread,

    You mentioned the Open High Limit Switch, I think thats whats wrong with my unit, where is it located? There are two wires going to a sensor on the fire chamber but no reset switch, might that be it, do I replace it, just unscrew it and put a new one in? If it's not resettable.
     
  13. Nov 13, 2011 #13

    Fitmiss

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    The blower motor was not running.

    For the benefit of others experiencing the same problem, mine was a bad control board. Hard starting the blower motor proved it was not a fault with the blower motor. The board was not sending enough juice to the blower motor to run. Changing the board fixed the problem.
     
  14. Nov 17, 2011 #14

    twingkey

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    sorry wrong post
     
    Last edited: Nov 17, 2011
  15. Jan 21, 2012 #15

    vgs8606

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    My blower on Trane XE90 is not running. It makes horrible buzzing sound and tries to move but extremely slowly. Trying to push it using wooden stick does not work. It feels as if a strong magnet is preventing it from moving. When the power is off, it spins freely.

    Technician was already here. When he showed up, it worked few times but is not working any more. He found out that even though igniter lights up, the burner only comes on after couple of tries. For some reason, the technician spent lots and lots of time trying to find the cause. Suffices to say, he did not. I really did not call him about the delayed burner because it had been like that as long as I could remember.

    He did not have the motor with him and had to be ordered. I had him check the starting capacitor. He swapped it but the behavior did not change. He has ordered the new motor and he will be here on Monday.

    I am trying to understand the theory behind the blower motor. The motor itself is not seized or jammed and turns fine when spun by hand. What kind of electrical fault would cause it to essentially jam when applied power? I am not sure if he checked the voltage going to the motor from the controller board but given that motor does seem to be getting the power. Unfortunately the motor is using the power to make the noise rather than spinning! From what I remember and also from watching some youtube video, the noise it is making is the characteristic motor starting noise except the motor does not start and the noise keeps on going. When it was working, that noise is there for a fraction of second until the motor comes up to the speed.

    I am now wondering if the circuit board is the culprit and is not sending the full power to the furnace. I also tried the blower in the air conditioning mode and it makes the same noise and the blower does want to spin. I believe heating (Yellow) and cooling (black) have different motor terminals.

    We have snow coming and I really would like to at least temporarily get the heat going. Most blower problems that I have found regarding this furnace on internet are either bad capacitor or jammed squirrel cage. I have neither.

    I would hate to have the technician come in with the new motor and then find out that now he thinks controller needs to replaced :-( I am willing to use the DMM to rule out bad controller. I would also like to get your opinion whether the symptoms are of bad motor or bad controller.

    I appreciate your help!
     

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