Error code
E: 99 4-way valve error
Applies to 6 models
ASUG09LZAS, ASUG12LZAS, ASUG15LZAS, AOUG09LZAH1, AOUG12LZAH1, AOUG15LZAH1
What this means
The indoor heat-exchanger temperature differs from room temperature by more than 20 °F (10 °C) in cooling or dry operation, or less than -20 °F (-10 °C) in heating. Connector, thermistor, solenoid coil, 4-way valve, or main-PCB failure may be involved.
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.