In split air conditioning systems, various types of motors are used in fans, both in indoor and outdoor units. Below are the most common types, their characteristics, and common failures.
1. Constant Speed AC Induction Motor
This is the most common motor used in fans located in the outdoor unit of traditional air conditioners. It operates through a rotating magnetic field that induces a current in the rotor, causing it to spin.
Characteristics:
- Reliable and relatively inexpensive.
- Lower energy efficiency compared to other motor types.
- Requires a capacitor for starting and operation.
- Basic control is performed using relays.
Connections:
- Uses three wires of the same thickness:
- One connects to the common pin of the internal windings.
- Another connects to one of the windings.
- The third connects to the capacitor.
Common Failures:
- Capacitor.
- Relay.
- Bearings.
2. Multi-Speed AC Induction Motor
These motors are most commonly used in fans of older split air conditioners’ indoor units. They operate through a rotating magnetic field that induces a current in the rotor, causing it to spin.
Characteristics:
- Reliable and relatively inexpensive.
- Lower energy efficiency compared to other motor types.
- Requires a capacitor for starting and operation.
- The control of power and each speed is performed using relays.
Connections:
- Uses three basic wires plus one additional wire for each extra speed, which connects to the motor’s common terminal.
Common Failures:
- Capacitor.
- Relay.
- Bearings.
- Loss of one speed.
3. Electronically Controlled AC Induction Motor with Triac
This type of motor also operates through a rotating magnetic field that induces a current in the rotor, causing it to spin.
Characteristics:
- Requires a capacitor for starting and operation.
- Control is performed through an electronic circuit mainly composed of a triac and an optocoupler circuit, allowing it to turn on, off, and control speed.
Connections:
- Uses three wires of the same thickness:
- One connects to the common pin of the internal windings.
- Another connects to one of the windings.
- The third connects to the capacitor.
- Speed variation is achieved by manipulating the voltage curve.
- Requires a speed sensor called a Hall effect sensor, which connects to the electronic board via three very thin wires, independent of the motor’s power supply wires.
Common Failures:
- Capacitor.
- Triac.
- Bearings.
- Hall effect sensor.
4. Brushless DC Motors (BLDC)
BLDC motors are increasingly popular in modern split air conditioning systems due to their high efficiency, lower energy consumption, quiet operation, and durability.
Characteristics:
- Speed variation is achieved electronically with high precision.
- Operates similarly to a DC motor but without brushes.
Connections in the Indoor Unit:
- Typically have five connection wires to the electronic board:
- Red wire: High voltage power supply (usually 300 V).
- Black wire: Ground (0 V).
- White wire: Power supply to the electronic controller inside the fan (usually 15 V).
- Yellow wire: Signal from the electronic controller of the outdoor unit’s board to the electronic board inside the fan.
- Blue wire: Indicates the motor shaft’s speed and position to the outdoor unit’s electronic board controller.
Connections in the Outdoor Unit:
- The BLDC motors used in the outdoor unit generally have three wires since their electronic board is located inside the outdoor unit’s main board:
- Power supply wire (high voltage).
- Ground wire.
- Speed signal wire from the outdoor unit.
Common Failures:
- Integrated circuit or IPM module that supplies power to the fan motor.
