Introduction: Repair a Fan That Won't Turn
In this Instructable, I will show how I repaired an oscillating pedestal fan of the type that is normally thrown away when it stops turning. You can usually get them working by applying lubricant to the ends of the motor but this only works for a while until the bearing get seized again. I always figured that the construction of them didn't allow for easy repairs. When the weather warmed up this May, I was sweltering one day and realizing that I still had this fan in the basement, I thought I would see if I could fix it. Upon taking it apart, I saw that it had metal bearings and lends itself very well to repair by anyone with a basic mechanical aptitude. The same applies to desk fans although some might have cheaper construction than others, but they all are built with similar construction.
1) Multi-purpose lubricating grease. (hardware store)
2) Long nosed pliers (hardware store)
3) Multi-bit screwdriver (hardware store)
4) Electrical solder and soldering iron. (hardware store)
5) Electrical tape. (hardware store)
6) Rags or paper towels
8) Container of Methyl Hydrate
9) Hose clamp pliers or something similar
Step 1: Start to Dismantle
Take off the front guard of the fan cage and remove the fan blade by turning the hand nut clockwise to loosen it. Behind the fan blade you will find another plastic nut the can be removed by turning it counter clockwise. You might need to use a pair of hose clamp pliers if it's too tight. Once the nut is removed, you can remove the rear guard.
Step 2: Disassemble the Plastic Motor Covers.
Once the rear guard is off you are just left with the plastic motor covers. It comes apart in two halves. There is a screw that holds the rear piece to the motor and there are two screws that hold the front piece to the motor. These need to be removed. Pull off the on/off speed control assembly knob. The other pull-out knob is the stationary or side to side control. It will require putting a flat blade screwdriver under it while gently pulling up with your fingers to remove it. Once these control knobs are removed, the motor assembly can be seen while still connected to the stand.
Step 3: Taking Apart the Motor and Checking the Capacitor
This motor is called a single phase, capacitor start, induction motor. The capacitor is the small black box with the two wires coming out of it. The purpose of this is to create a phase difference between the stator voltage and the rotor voltage. This voltage phase difference is called "slip" and creates the torque in the motor. If there was no capacitor, the motor would not turn. If you want to check this capacitor, you can check it with a capacitance meter or use the ohms setting on your multimeter. Remove one of the wires. For 30 seconds put a short across the capacitor with a wire or alligator lead to remove any residual voltage to protect your meter and put your meter on at least the 1K setting and watch the capacitor slowly charge up. If it doesn't, you know your capacitor is bad. Replace with another non polarized capacitor or create your own with two electrolytics with the two positive leads connected together. The voltage rating should be at least 250 volts or higher and the capacitor should be at least 4uF. If you are making one yourself, make sure the two electrolytics are at least 8 uF each because capacitance halves in series. The motor case consists of four pieces, the rotating piece called the rotor, the middle piece with the coils on it which is called the stator and the two end pieces with hold the bearings for the rotor. These all are held together with four screws. Before you take the motor apart you need to remove the pivoting arm which is held on by a screw that connects to the nylon eccentric and also take the green wire off of its screw connecting it to the case. Take these out and the motor comes apart like the picture. Take care to do this because the wires in the coils break easily especially where the power comes in from the outside of the motor.
Step 4: Take Out Rotor and Clean Bearings
Gently take out the rotor and clean both ends with methyl hydrate. Do the same to the bearing that they fit into. Once clean and dry, coat both bearings with a layer of grease. Also clean inside of coils and make sure there is no debris in there. Also clean areas around bearings. Put assembly very carefully together examining wires for any breaks. One of the coil wires was broken near where it connects to the incoming insulated wires. I soldered in a new wire and connected. As you are bringing wires together you might want to put a bit of electrical tape around them to hold them together and insulate them. Put the rotor gently in the coil assembly and connect the two bearing pieces to it with the four screws. Reconnect the pivoting piece to the nylon eccentric with the screw and also do this to the green wire connected to the metal chassis by a screw. Check to see that the rotor spins easily in its bearings.
Step 5: Reconnect Capacitor and Re-fit in Plastic Covers
Re-solder any wires that have been removed from the capacitor and if it was necessary to re-spice any wires, do this now. take the plastic assemblies and attach them with the one screw on the big piece and two screws on the big plastic piece. Once everything is together, the fan assembly can be mounted on the pedestal. Gently remount the two control knobs. Now plug the fan in and make sure it works. Try the different speeds and pull out the oscillating control to make sure it works. If the oscillating mechanism is sticking, gently help it along while running the fan on the lowest speed. Chances are it will work after being helped along for a while. leave the fan on for 30 minutes and then check for no burning smell or unusual heat coming from the motor.
Step 6: Re-attach Rear Fan Guard, Fan Blade and Front Guard
Re-attach the rear fan guard with the finger nut making sure to not over tighten. The fan blade should now be attached with the backwards hand nut. Now re-install the front guard carefully. The repaired fan is now complete.