AIRSTAGE | Technical Support Procedure

3 Wire Remote Signal Test

Testing the Y1, Y2 and Y3 wired remote-controller circuit
Electrical safety: This procedure must only be completed by a suitably qualified service technician. Isolate power before removing or reconnecting controller wiring. Take care not to short Y1, Y2 or Y3 during live voltage testing.
Purpose: Use this test to determine whether a three-wire wall controller, controller cable or indoor-unit control circuit is producing the correct supply and communication signal.

1. Terminal Identification

TerminalTypical wire colourFunction
Y1RedApproximately 12 V DC supply
Y2WhiteCommunication signal
Y3BlackCommon / 0 V reference
Meter setting: Set the multimeter to DC volts. Carry out all voltage measurements with reference to Y3 unless otherwise stated.

2. Test Procedure

Step 1 — Confirm controller supply voltage
  1. Leave the three controller wires connected.
  2. Measure DC voltage between Y1 and Y3 at the rear of the wall controller.
  3. Expected reading: approximately 12 V DC.
  4. The voltage should generally be no lower than 11.4 V DC.
Expected result: Stable voltage close to 12 V DC.

Step 2 — Test the wall-controller signal output
  1. Isolate power before disconnecting any wiring.
  2. Disconnect the Y2 wire from the wall-controller terminal.
  3. Restore power and measure between the wall controller's Y2 terminal and Y3.
  4. Expected reading: a fluctuating or pulsing signal of approximately 7–11 V DC. Some meters may display fluctuations up to approximately 12 V DC.
Expected result: A changing DC voltage rather than a steady fixed reading.

Step 3 — Test the cable and indoor-unit signal
  1. Keep the Y2 wire disconnected from the wall controller.
  2. Measure between the disconnected Y2 cable conductor going to the indoor unit and Y3.
  3. Expected reading: a fluctuating or pulsing signal of approximately 7–11 V DC. Some meters may display fluctuations up to approximately 12 V DC.
Expected result: A changing DC communication signal from the indoor-unit side of the circuit.
Important: Isolate power before reconnecting Y2. Confirm all three conductors are secured in the correct terminals before restoring normal operation.

3. Result Interpretation

Test resultLikely area to investigate
No voltage, or substantially less than 11.4 V DC, between Y1 and Y3Indoor-unit controller supply, indoor PCB, wiring connection, cable resistance or short circuit.
Correct Y1–Y3 supply, but no pulse between the wall controller's Y2 terminal and Y3Wall controller may be faulty or not transmitting correctly.
Correct pulse at the controller, but no pulse on the disconnected Y2 cable going to the indoor unitOpen circuit, incorrect termination, damaged cable, poor joint or high resistance in the controller wiring.
Pulse is present on both sides, but communication fault remainsCheck polarity, terminal allocation, cable type, cable length, electrical interference, loose connections, controller compatibility and indoor PCB operation.

4. Additional Checks

  • Confirm Y1, Y2 and Y3 have not been crossed at either end.
  • Inspect for loose terminals, damaged conductors or poor joins.
  • Check the controller cable for continuity and insulation resistance with power isolated.
  • Confirm the cable is not run alongside mains wiring where induced electrical noise may affect communication.
  • Check that the installed wall controller is compatible with the indoor unit.
  • After testing, reconnect all wiring and confirm normal controller operation and error-code status.
Technical summary: Y1 to Y3 provides the nominal 12 V DC supply. Y2 is the communication conductor and should display a pulsing voltage when tested against Y3. Separating the Y2 wire allows the technician to compare the wall-controller signal with the indoor-unit side of the circuit.