enter image description hereHave a used microwave oven exhaust fan which I plan to use as a stand alone fan. The wiring on the fan is the enclosed picture. The question is how do I wire this to work as a stand alone fan? enter image description here

Update: ThreePhaseEel and others thank you.

Is the T/P symbol on the motor schematic stands for Thermal Protection? Right below the schematic diagram of the motor in big letters it states Thermally Protected.

The external thermal protection is probably for knowing when the fan has to come on for microwave usage, because the microwave needs to cool and NOT for protection of the motor itself. So I think this thermal protection and one of the yellow wires going to this thermal protection can be eliminated if the unit is going to be used for a stand alone fan.

Just to clarify: So a double switch is needed if both speeds are to be used but if only high speed is going to be used then just the blue wire needs to be connected to power and it can be turned on/off by connecting and disconnecting the power cord.

For a double switch the blue wire from the motor to one side of switch for high speed and yellow wire to the other side of the switch for low speed. The other side of the switch gets the black wire from the 3 prong plug.

The black wire from the motor is connected to the white/neutral wire from the 3 prong plug to complete the circuit.

What about the green wire of the 3 prong plug? Where does that goes or is it left out?

The capacitor stays for the initial motor torque. Nothing to do there except to enclose it in the same box as the switch and to insulate the wires going to it


You need to install a switch (toggle, rocker, paddle, etc.). Connect the Black wire from the plug cord to a terminal on the switch. This will be the Hot wire that carries the power to motor. On the other switch terminal you can either wire the Blue (for High speed) or Yellow (for Low speed) that come from the motor of the fan.

You should probably keep the Thermal Fuse as it may be protecting the motor and an integral part of the system. The Thermal Fuse is a safety device that has a bi-metal disc inside that connects the Blue and Yellow wires to complete the circuit. If it senses a higher heat than what it is calibrated for the disc warps and opens the circuit stopping the flow of power until it cools and snaps back and closes the circuit. Always enclose a switch with an UL approved enclosure with a cover plate and wire clamps.

You could probably use a Double Switch [![enter image description here][1]][1]

[1]: https://i.stack.imgur.com/tnIYd.png so that the Dual Speeds will be available.

  • I think the thermal protector needs to stay to provide overload protection to the motor since it seems that the motor doesn't have thermal protection built in Dec 19 '20 at 1:29
  • It would be best. I agree.
    – ojait
    Dec 19 '20 at 1:37
  • Actually, it looks like the motor's internally thermally protected, my bad[ Dec 19 '20 at 2:04

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