Single-Speed Fan Motor Connection

In this article, we will explore the connection and main characteristics of single-speed fan motors used in single-phase air conditioning units.

Three-Wire Motor

The diagram of a three-wire motor is presented on the screen. This motor is single-speed and its operation is controlled by a relay located on the electronic board.

To identify the wires of any fan and use the diagram, the following procedure should be followed:

1. Resistance Measurement: Using a multimeter set to the ohm scale, measure all electrical resistances between two wires.
2. Capacitor Identification: The pair of wires with the highest resistance is considered the wires for connecting the motor capacitor.
3. Line and Neutral Determination: The pair of wires with the lowest resistance is identified as the line wire and the neutral wire.
4. Neutral Wire Designation: The color of the wire that shows both the highest and lowest resistance measurements between wire pairs is designated as the neutral wire. In this case, the red wire meets this characteristic.
5. Line Wire Determination: The line wire is determined by the lowest resistance measurement, noting that the red wire is neutral. Therefore, by elimination, the black wire will be the line.
6. Capacitor Connection: The wires for connecting the capacitor are the blue wire and the same red wire using a jumper.

Four-Wire Motor

The diagram of a four-wire motor is presented next. This motor is also single-speed and controlled by a relay on the electronic board. The wire identification process is repeated with some variations:

1. Resistance Measurement: Using a multimeter set to the ohm scale, measure all electrical resistances between two wires.
2. Capacitor Identification: The pair of wires with the highest electrical resistance is the pair used to connect the capacitor.
3. Line and Neutral Determination: The pair of wires with the lowest resistance is identified as the line wire and the neutral wire.
4. Interchangeable Wires: If there is a pair of wires that shows a near-zero resistance measurement, it indicates that they come from the same point, meaning they are interchangeable.
5. Neutral Wire Designation: The color that shows both the highest and lowest resistance measurements is assigned as the neutral wire. In this case, the yellow wire meets this characteristic and will be the neutral.
6. Line Wire Determination: With the lowest resistance measurement, the line wire can now be determined. Since the yellow wire is the neutral, by elimination, the black wire will be the line.
7. Connection Similarities: In reality, the connections for both three-wire and four-wire single-speed motors are similar, with the difference that the four-wire motor has two wires that are internally connected.