This error code indicates a communication fault. Please the DC as follows:
- Near the isolation switch, turn the power off.
- Disconnect the Signal Wire off the indoor terminal block.
- Turn the unit on and let it operate in the standby mode.
- Test the DC output from the signal wire, which connects to the indoor unit and ground, using a multimeter.
- If it shows low stable voltage, the indoor PCB is operating properly.
- Test the output signal on the terminal block of the outdoor unit’s PCB and grounding using the same method.
- If the voltage is pulsing near the low 50’s, the outdoor PCB is operating properly.
- If it is 0 DC volts, the PCB is bad.
Using the isolation switch, disconnect the main power supply to the indoor unit. Turn it back on after a minute or so and run the Auto mode. Set the temperature at two degrees above or below the current room air temperature.