Fehlercodes: L18_ECOi_ME1

Alarm Code L18
Alarm meaning 4-way valve operation failure
Alarm conditions During heating operation (Comp. ON), the highest detected temperature at an outdoor unit heat exchanger (EXG 1, EXG 2, EXL 1, or EXL 2) was 20°C or more above the outdoor air temperature (Air Temp.) continuously for 5 minutes or longer, or the detected suction temperature (SCT) was 20°C or more above the outdoor air temperature continuously for 5 minutes or longer.
Probable cause
  1. A unit that uses R407C refrigerant, or a R22 model unit, was connected by mistake. The 4-way valve connector (20S CN022) has become disconnected from the control PCB. 
  2. The 4-way valve circuit is locked (malfunctioning).
Check
  1. Check the 4-way valve connector (20S CN022).
  2. If the connector is normal, check the 4-way valve wiring and the PCB circuit.
Correction If the connector is normal, correct or replace the problem locations.
Example –
Notes –