Error code
live-operation-lamp-off-timer-lamp-4-blinks Serial signal fault at start-up (forward)
How it shows on the unit Funktion (OPERATION) LED off, Timer LED 4 blinks
Applies to 4 models
ASYB09LDC, AOYS09LDC, ASYB12LDC, AOYS12LDC
What this means
Serial-signal fault (forward direction) at start of operation.
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.
See the Fujitsu manual (hosted by an authorized distributor)Hosted by an authorized distributor rather than by the manufacturer. We link to manuals, we never host them.