Communication error between Main PCB and Inverter PCB
E203 will occur when the main PCB in the outdoor unit cannot communicate with the inverter PCB. While this error may be caused by a fault with the main PCB, or the inverter PCB, it can also be caused by the inverter PCB shutting down due to the detection of a short. The inverter PCB has 3 lights on the side of it, Red, Green and Yellow. If these lights are not on but, power is being supplied to the inverter PCB, then its recommended to check the condenser fan motors. If a short has occurred in the internal driver module of a condenser fan motor, then the inverter PCB will shut down to protect itself from damage. Resistance readings of the fan motors can be checked, but a simple test is to power the system down, wait a few minutes, then unplug the fan motors from the inverter PCB. Re-energize the system and check the lights on the inverter PCB, if the lights come straight on, then chances are high the system has a faulty condenser fan motor. (These tests should only be undertaken by a qualified person).
Fan Motor Resistance Readings.
Pin 1 (Red) – Pin 3 (Black) = Over 1 Meg Ohm
Pin 3 (Black) – Pin 4 (White) = Over 1 K Ohm
Pin 3 (Black) – Pin 5 (Yellow) = Over 1 K Ohm
Pin 3 (Black) – Pin 6 (Blue) = Over 1 K Ohm
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