Error code
0.5-second continuous flash Miswiring or serial-signal error
Applies to 16 models
MSZ-AP25VG-E1, MSZ-AP25VG-EN1, MSZ-AP35VG-E1, MSZ-AP35VG-EN1, MSZ-AP42VG-E1, MSZ-AP42VG-EN1, MSZ-AP50VG-E1, MSZ-AP50VG-EN1, MSZ-AP25VGK-E1, MSZ-AP25VGK-EN1, MSZ-AP35VGK-E1, MSZ-AP35VGK-EN1, MSZ-AP42VGK-E1, MSZ-AP42VGK-EN1, MSZ-AP50VGK-E1, MSZ-AP50VGK-EN1
What this means
The indoor unit has not received the outdoor-unit serial signal for up to 6 minutes, or its stored outdoor-unit compatibility information is inconsistent.
When to call a technician
This fault involves refrigerant, pressure, or electrical work that must be handled by a certified technician under EU F-gas rules. Do not attempt to open the refrigerant circuit, access mains wiring, or adjust pressure components yourself. Contact a qualified installer or servicer for this one.