Overview
The 3-Wire Remote Signal Test verifies communication integrity between the wall-mounted remote controller and the indoor unit.
This test confirms DC supply voltage and signal pulse transmission to ensure correct system control operation.
Safety Warning
⚠️ Low Voltage Circuit – Handle with Care
Always use insulated multimeter probes and avoid shorting terminals.
Testing is conducted on live DC circuits (approx. 12V DC).
Testing Conditions
Ensure the wall controller and indoor unit are connected and powered.
Use a digital multimeter capable of measuring DC voltage.
Test points: Y1 (12V), Y2 (Signal), and Y3 (Common) terminals located on the rear of the remote controller.
Terminal Identification
| Terminal | Wire Colour | Function |
|---|---|---|
| Y1 | Red | +12V DC Power |
| Y2 | White | Signal Line |
| Y3 | Black | Common (GND) |
Procedure
1. Verify DC Power Supply
Measure voltage between Y1 (Red) and Y3 (Black).
Expected reading: 12V DC (no less than 11.4V DC).
If no voltage is present, the controller PCB or power supply may be faulty.
2. Verify Signal Output from Remote
Disconnect the Y2 (White) signal wire from the terminal.
Measure between Y2 (White) and Y3 (Black) at the controller.
Expected reading: Fluctuating 7–12V DC (pulsed) — indicating active data transmission.
3. Verify Signal from Indoor Unit
With Y2 disconnected, measure between the Y3 (Black) terminal and the Y2 wire leading to the indoor unit.
Expected reading: Fluctuating 7–12V DC (pulsed).
This confirms signal communication between the remote and indoor PCB.
4. Confirm Indoor–Outdoor Communication
If all remote signal readings are correct, verify data transmission between indoor and outdoor units using the service communication test procedure.
Diagnosis and Interpretation
| Observation | Diagnosis | Recommended Action |
|---|---|---|
| 12V DC present between Y1–Y3 | Power supply normal | Proceed with signal test |
| No voltage between Y1–Y3 | Faulty controller or missing DC supply | Replace controller PCB |
| 7–12V fluctuating signal between Y2–Y3 | Signal circuit normal | No fault detected |
| No fluctuation on Y2–Y3 | Signal transmission fault | Replace controller or indoor PCB |
| Signal correct but no operation | Indoor–Outdoor comms fault | Perform communication check |
Technical Notes
The 3-wire communication uses a 12V DC power and data pulse system.
A fluctuating signal (7–12V DC) confirms active digital communication.
Stable voltage (no fluctuation) indicates a stuck signal or controller fault.
Always test continuity of the Y2 communication line if faults persist.
