The air conditioner fan speed sensor, based on the Hall effect, sends a digital pulse signal to the electronic board. The frequency of these pulses reflects the rotational speed of the fan motor shaft, enabling the controller to manage its operation precisely.
Principle of Operation
The sensor operates using the Hall effect principle, where a magnetic field passing through a conductor generates a voltage proportional to the speed of the field. This mechanism allows accurate determination of the fan’s speed and communicates it to the unit’s controller.
Typically, the sensor uses three wires:
- Power Supply (5V or 12V)
- Ground
- Output Signal
Identifying the Wires:
- Power the electronic board.
- Use a multimeter set to DC voltage.
- The pin showing 5V is the power supply.
- The pin where the black probe detects continuity is the ground.
- The remaining pin is the output signal.
Diagnosing the Hall Effect Sensor
1. Connection Verification
- Ensure there are no loose, damaged, or improperly connected wires.
2. Power Voltage Measurement
- Use a multimeter to check the sensor’s voltage (5V or 12V per specifications).
- If the voltage is incorrect, inspect the power source and connections.
3. Signal Testing
- Place the black probe of the multimeter on ground and the red probe on the signal pin.
- Manually rotate the fan.
- Observe voltage changes corresponding to sensor pulses. Lack of variations may indicate a faulty sensor.
4. Oscilloscope Testing
- An oscilloscope can measure the output signal as a square waveform.
- A functional sensor should produce a uniform wave reflecting the fan’s speed.
5. Sensor Replacement
- If the sensor fails to respond, replace it according to the equipment’s specifications.
Further Checks
1. Fan Motor Inspection
- If the sensor is working, inspect the fan motor for obstructions, wear, or mechanical issues.
2. Controller Verification
- If the signal is not interpreted correctly, the electronic controller may need replacement.
Common Error Codes
- H6: Indicates internal fan malfunctions in various brands.
- E6/E7 (TCL): Points to issues with the internal fan motor.
- E8 (Midea, Akai, Carrier): Relates to faults in the internal or external fan, depending on the model.
- F5:
- In Carrier and other brands, signifies external fan failure.
- In Midea, can be linked to the condenser fan.
