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Fan not turning on...

2K views 10 replies 7 participants last post by  beenthere 
#1 ·
I have a approx 12 yr old Trane furnace that the blower motor will not kick on. When it tries to come on, I just get a hum. What are some potential causes for this? The only part numbers I can see are on the Integrated Ignition module, which are a White-Rodgers 50A50-571. The diagnostic light blinks non-stop at about 1 sec intervals, which I believe means there is no fault. Any ideas?
 
#2 ·
Open the filter area and see if the blower cage is spinning. Do not put your hands in there with the power on. If it is not spinning, turn the power off to the furnace and see if you can spin the blower cage by hand. If it feels tight or doesn't move at all, more than likely the bearings are going or have seized on the motor and you need another one.
 
#8 · (Edited)
won't be the capacitor if it runs fine on heating and you said it started right up again on cooling. most likely the fan relay to turn the ac fan speed on is sticking off intermittently and usually is built into that integrated control which may now need replacing. if the capacitor fails then it runs slowly as it gives the motor torque to get up to speed. on the outdoor unit it can get bulged and fail completely and won't run but on the indoor fan it just slows down and overheats the motor. 10-12 yrs is average life expectancy for those boards.

put a piece of strong tape over the switch behind the fan door. next time the fan won't start remove the door and tap that control a few times. if the relay is sticking and it starts the Voila, case solved. otherwise you need to remove the wire to the fan stamped Cool speed and see if it is getting 120 volts to ground. if it is then the motor may have a bad winding and need replacing which is rare.
 
#10 ·
Hello,
I have a similar issue with my Trane XE 80. The outdoor compressor is working fine and the feeder duct is cool but the fan will not blow. I reached in and the fan moves freely. When the black switch is pressed simulating the cover being on, there is a click and humming but no fan turning. Is this behavior of a bad capacitor? Any help would be greatly appreciated!
 
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