Blower will spin freely and smoothly when there is no power applied to it. I can watch the blower and it does want to spin in the correct direction but it is only crawling, like one degree every few seconds. Trying to push it by wooden stick shows lots of resistance as if there is a giant magnet holding it back. Start capacitor was replaced but that had no difference in the symptoms.
I checked the motor stator windings and they all checked out (4 - 6 ohms). I checked the voltage coming out of the controller when it commands the motor to spin. No load voltage is 120VAC and when the motor is making the noise, it is at 118VAC. I also tried all four leads and they all noises, some more some less.
When the motor spins freely without power, there is NO axial or lateral play. When the power is applied, I do not see any shift. This tells me that motor is mechanically sound. I am at a loss as to what can electrically go wrong with rotor on this type of motor. I am under impression that they are pretty much bulletproof.
I am concluding that I need new motor and motor only i.e. the fan assembly is fine (because it spins freely without power) and controller is fine (because it is providing 120VAC to the motor).
I would like to apply direct 120VAC to the motor but I do not like the unsafe aspect of it. Given that I have already measured the live voltage to the motor coming out of the controller at the junction and it is showing 120V, there is no logical reason to think applying direct wall power would make any difference. Can you come up with a scenario under which this assumption would be wrong?
As you can imagine, the house is very cold. I already had a technician come in and the motor is on the order. But I definitely want to make sure putting the new motor is going to fix it. I just can not take "oops, we need more parts and they need to be ordered" saga anymore.
Trane XE90 forced hot air, installed YR2000