Trane XE-90 blower makes noise and barely nudges

Discussion in 'HVAC' started by vgs8606, Jan 21, 2012.

  1. Jan 21, 2012 #1





    Jan 21, 2012
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    Interestingly, the noise is exactly what they all make for fraction of a second before the blower starts and picks up the speed. At least that is how it was on mine since new. A youtube video explaining and cleaning the blower exhibit similar noise, once again only for a fraction of second on startup. (Oiling the furnace blower motor - [ame=]Oiling the furnace blower motor - YouTube[/ame] @5:40)

    As of yesterday, my blower only makes that big noise all the time and the cage fan barely attempts to spin. I already had a technician but he did not have a spare fan. While he showed up, the blower ran for few cycles for him but not anymore. The fan cage has no obstruction. I can spin it by hand very easily. However, as soon as controller commands it to spin, it behaves as if a giant magnet is preventing it from spinning. I tried to "assist" in starting but as I said, it "chokes" itself as long as there is power going to it. I had technician swap the starting capacitor but the behavior did not change.

    I have measured voltage at the controller with the blower disconnected (YEL wire) and it shows 110V when controller commands the blower. The two pins on the capacitor shows 140V (?) when the blower is hooked up back to the controller. I would still like to rule out any controller problems by directly starting the blower. What is the best and safe way to do that? My idea of sticking a wire between wall and blower power lead scares me.

    What bothers me most is that doing research on web has not come across this particular type of failure i.e. blower fan spins freely by hand but jams itself when the power is applied. I do not see any lateral movement of the fan. Fan starts "nudging" in the correct direction. Given that and also trying the new capacitor and trying to push it by wooden stick should rule out the bad capacitor.

    Are internal rotor winding burned up? So instead of creating opposing emf, the core of the rotor is being attracted to the stator and preventing it from spinning. Does that explanation makes sense?

    I already have the motor on the order and the technician is going to install it on Monday. I want to make sure it is the motor which is bad and not the controller. The house is getting colder and I would like to see if there is anything that I can do to get the heat starting at least temporarily. Any way to stick a leaf blower somewhere in the system? :)


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