E422/C422 will basically be displayed if the indoor unit evaporator inlet sensors detects no temperature change or, an abnormal temperature change, after 5 minutes of the system running in cooling mode. The fault points mainly to an issue with the EEV (electronic expansion valve) or a refrigerant charge issue. That being said, the indoor unit sensor can play a big part in triggering this error code. First thing to check in regard to an E422 error is that the evaporator sensor hasn’t come loose from the evaporator and that its resistance value is correct. The evaporator sensor should read 10Kohm at 25 degrees Celsius. An out of range evaporator sensor may not be out of range enough to through a sensor error (E122), but it may be able to confuse the system into thinking there is an refrigeration issue. When a Samsung system is power cycled, the EEV will drive fully closed, then fully open again. A ticking sound will come from the valve during this period. If no ticking can be herd, an issue may be present with the EEV. Please see below for further information in regard to diagnosing an E422/C422 error.