Mitsubishi Air Conditioner Error Codes
| Code Text | Description | Cause | Check Procedure |
|---|---|---|---|
| 0403 | Serial Transmission Abnormality. Transmission fault between PCB’s in the outdoor unit. | The fault occurs when there is a communication issue between PCB’s in the outdoor unit.-If the model number is a YMFB, YMFC or YEM-A then the fault is between the main board and inverter board.-If the model number is YGMA, YHMA, YJMA, YKMA or YLMA then the issue can be between the main board and inverter board or main board and fan board. | Check for poor connections and broken wiring between the boards.If the unit is a YGMA, YHMA, YJMA, YKMA or YLMA check the error detail code using the dip-switches section of the app to determine which PCB’s the transmission fault is with. If the detail code is 1, then the issue is between the main board and inverter board. If the detail code is 5 then the issue is between the main board and fan board.Then check for poor connections between the PCB’s. |
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