Crazy Pete's Projects




May 20th 2012:

Ever had a cheap oscillating fan stop working? I had an HTF3110A tower fan , and figured, "They cost thirty bucks, how hard could it be to fix it?"

Materials:

Part no.
Description
QTY
Price
Source
270-1322
Thermal Fuse
1
$0.75
Radio Shack
n/a
12Ga butt connectors
about 6
n/a
local hardware store
n/a
pop rivets (size may vary)
2
n/a
local hardware store
n/a
Engine builders lube
n/a
n/a
local auto parts store
n/a
WD-40
n/a
n/a
local auto parts store
n/a
Zip ties
about 12
n/a
local hardware store

Tools:

  • Wire Strippers
  • Phillips head #1
  • Flat head for prying
  • Soldering iron
  • Butt connector crimper
  • Multimeter
  • Drill and bits

Repair procedure:

  1.  Remove 9 screws that hold the rear cover on: No
                    rear cover
  2. Remove the fan blades assembly by loosening a locking screw at the base of the fan, connecting it to the motor. Then, lift the fan assembly off the motor shaft. The metal bracket holding the upper bearing on the fan blades may bend abit, no big deal, bend it back if needed:
    Fan
                    blade removed
  3. The motor is held in place by four screws on it's flanges. They can be removed to pull out the motor. Some wire restraints may also need to be removed here:Motor
                    removed
  4. The simple brushless A/C induction motor (similar to a ceiling fan) has a housing of two stamped sheet metal pieces, held together by tabs built into themselves and folded though holes in the other. The easiest way to get inside is to drill them out:
    Drill
                    it
  5. Pry the motor housing apart with a flat head:Pry it
  6. The rotor has seized and will not turn, probably due to poor lubrication from the factory. This, I believe to be the initial fault. I removed it from the upper potion of the motor housing and cleaned it up with some WD-40:
    Rotor
  7. I  used the flat head again to remove the stator from the lower motor housing. Note the wires I clipped at the fan, but left their respective connector on the wire they connected to. Since each wire did not necessarily connect back to the same color wire, leaving a small amount of the original insulation kept me from having to label the wires:
    Stator
    At this point I also used a multimeter to check continuity on all the wires. They grey wire had none. It was connected to the thermal protection fuse in the next step.
  8. After the rotor seized and stopped turning, the coils heated up with no cooling, this caused the thermal fuse to blow. This one appears to be rated at 115 degrees Celsius (239 Fahrenheit). Mine is not exact but a suitable replacement at 129 degrees Celsius (264 Fahrenheit)  At this point I could have just bypassed the fuse to make the motor spin, but I don't like burning down my house. NEVER DEFEAT A SAFETY INTERLOCK OR SYSTEM!
    Thermalfuse
    Bonus Question : Why does Google no longer convert C to F for you? Instead of showing me the result I asked for, Google just searched, found, and directed me to an online converter.
  9. I cut the wax string holding the wires and coils together so I could remove the insulating tube that isolates the colored wires from their coil leads:
    WAXY!
  10. Since the thermal fuse is heat sensitive, you must be very careful when soldering it to the leads. I used long leads and a keyring acted as a good heat sink:It's
                    gonna get HOT!
  11. After soldering the fuse on, I slipped the little insulator tubes back on the leads and used small zip ties to secure everything. I did not have any waxy string. Make sure you keep the new thermal fuse near the coil so that it will blow when it gets hot:
    reassembled
  12. The next steps are all reassembly. It is the reverse of the above, with a few minor differences. Such as better lubricant:
    lube
  13. pop rivets to hold the motor together and butt connectors are aready crimped on this side:A
                    riveting experience
  14. Here the motor is remounted and wires are reconnected. I used this time to clean the dust from all the plastice parts:
    reassebmled
  15. The motor spins freely and the covers are screwed back on after the fan blades are installed. The fan once again works great.


Thanks for making it this far. Be advised I am working on getting a better camera, and that reading this page about what I did in no way makes me qualified to train you to be an expert in electrical, electronics, electricity, or the basic use of tools and not eating grease. This is all informational only so others can see what I did. If you burn down you house or hurt yourself or others in anyway, it's your fault, not mine.

Please send any feedback to me.

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