Error code
E: 11 Serial communication error
Applies to 6 models
ASUG09LZAS, ASUG12LZAS, ASUG15LZAS, AOUG09LZAH1, AOUG12LZAH1, AOUG15LZAH1
What this means
Communication failure involving serial signaling between the indoor and outdoor units. The combined causes include missing outdoor-to-indoor reverse-transfer communication, missing indoor-to-outdoor forward-transfer communication, connection problems, electrical noise, PCB failure, or an indoor or outdoor fan-motor fault.
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.