Troubleshooting Broken AC Motor House Fan: Tips and Tricks

[Chevy65]

Hi, my brother asked me to troubleshoot his electrical house fan. He tripped over it and then stepped on the fan blade which then caused one of the fan blade rivets to break off. A closer inspection revealed that the rivet did break off, however, the bracket that is attached to the electrical motor housing, which holds the fan assembly to the stand foundation has also broke off. I believe I made a mistake and did not check to see if the fan motor was working or not before I took it apart. Anyway, I decided to fabricate my own bracket to replace the broken one. I do have pictures of the broken bracket before the repaires where made, and of the new bracket installed after the repairs were made. I can provide these pictures to who ever can provide me with an email address. I have no idea if pictures can be uploaded to this site. So, after I reassembled the fan assembly and applied voltage to the fan motor, it spun for a second then froze up, and I can hear the motor humming. With no voltage applied, the armature spins freely, and it appears to me that I don't have a misalignment problem, not absolutely sure though. With the voltage applied and the motor humming, I tried to spin the armature to help it get started, it responded as if it was locked, would not spin. Can anyone support me with this problem? How can I troubleshoot this problem to see what is wrong? If anyone prefers to email me privately, my email address is: Chevy66@hawaii.rr.com. Thank you for your support, Tommy.

 

[Chevy65]

Update! I tried troubleshooting the fan to see if I could find the problem. First of all, the fan is the Holmes Model: Hasf 1710 Pedestal Oscillating type used in the house. I tried switching the fan speed selector to see if the fan would spin in anyone of the speeds. It appears to be a 3 speed fan. For whatever reason, the armature would spin in the second speed mode intermittently. Sometimes it would spin for approximately half a minute then it would freeze up. Sometimes it would spin for a little longer than freeze up again. And then again, sometimes it would not spin in any speed. I'm wondering if the switch got damaged when the fan feel to the floor. There are four wires: black, red, blue and brown. Can anyone identify what each wire is for? Does anyone have the schematics for this fan? There is also a small black box inside the fan assembly. Is that a capacitor? Could that be the problem? Any suggestions? Thank you, Tommy.

 

[MATLABdude]

By "locks up", do you mean that it brakes, and goes from (full?) speed to a halt near instantaneously, or does it more coast to a stop?

If it brakes (and always does so at the same position), some of the connections to your motor coils may have been jarred loose, such that the coils are no longer energizing (or, energize until the fan reaches a certain level of vibration, at which point, it stops energizing). If it's a brushed motor, the brushes may also have been jarred loose.

Conversely, you may have some shorts in the coil contacts (or worse yet, intermittent shorts).

To (maybe) fix the above two, you'd have to touch up the electrical connections (with the fan disconnected from the wall, of course) with a soldering iron. Or reposition the brushes (if applicable).

Not quite sure of how the speed control works on there (probably a triac, and possibly a rheostat, a.k.a. big power potentiometer), but these may be cracked or may have come loose (or are making intermittent electrical connection).

In any case, isn't this fan $35 at Amazon?

 

[berkeman]

In any case, isn't this fan $35 at Amazon?

Exactly. I'd strongly suggest not putting that damaged fan back into service, even if you think you've fixed it. Fans are left on and unattended for long periods of time, so it's a real risk for starting a fire if it has loose parts or other damage inside of it. If you're experienced with AC Mains devices and are just looking to figure out and fix the problems before throwing away the fan, you may be okay. But please don't try to fix that fan and put it back into regular service. Just mark it up as an accident, and replace it.

 

[dlgoff]

"...it responded as if it was locked, would not spin."
Your brother probably broke one of the motors bearings causing the armature to jam into the fields. So I agree with berkeman that you should not use it. It's much easier and cheaper to just buy a new one.

 

[Chevy65]

Hi Guy's, yes these fans are very inexpensive. They run anywhere from $35 to $60 dollars. I think when my brother dropped it, the bearing clearances got thrown out of alignment, which is causing the armature to lock up. When I say lock up, I mean it stops instantly, it does not rotate to a slow stop. That's my thought anyway. There may be other problems as well, like the ones mentioned by MATLUBdude. So yes, I will tell my brother that he has to shop for a new fan. It is surely not worth trying to fix it at this time. I remember seeing a fan like this in a department store catch on fire. Once it starts to burn, it goes quickly. I thank you all for your outstanding support, Tommy.