03
Fujitsu Split AC
Severity: ModerateWhat Does This Error Mean?
Error 03 on a Fujitsu AC is a communication error — the indoor unit and outdoor unit have lost the signal connection between them. This signal wire carries control data between the two units. A broken wire, loose terminal, outdoor unit power issue, or PCB fault on either unit can cause Error 03.
Affected Models
- Fujitsu ASTG Series
- Fujitsu ASYG Series
- Fujitsu AOTG Series
- Fujitsu Inverter Split AC (all models)
- Fujitsu General Split AC
Common Causes
- Communication wire (signal wire in the interconnecting cable) damaged or disconnected
- Outdoor unit not receiving power — tripped breaker or blown fuse
- Outdoor PCB fault preventing communication
- Indoor PCB communication circuit fault
- Terminal block connections loose at either the indoor or outdoor unit
- Power surge corrupting the communication protocol
How to Fix It
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Confirm the outdoor unit has power.
Check the electrical panel for a tripped breaker dedicated to the outdoor unit or the AC circuit generally. Also check for an isolator switch near the outdoor unit.
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Turn off both units at the circuit breaker, wait 60 seconds, and restore power.
A complete simultaneous reset of both PCBs can clear a communication error caused by a power glitch or temporary fault.
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Listen for the outdoor unit starting after restart.
A completely silent outdoor unit after restart points to a power or PCB fault on the outdoor side rather than a wiring fault.
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If Error 03 persists, call a Fujitsu service technician.
The technician will test the signal wire continuity and voltage at both ends to pinpoint where the communication is breaking down.
When to Call a Professional
If a full power cycle does not clear Error 03, contact a Fujitsu authorised technician. Wiring between units may run through walls and require specialist tools to trace and test.
Frequently Asked Questions
Why did Error 03 appear after a power cut?
Power interruptions and voltage spikes when power is restored can disrupt the communication handshake between the indoor and outdoor PCBs. A full power cycle (breaker off for 60 seconds) usually resolves this. If it happens frequently after power events, a voltage stabiliser on the AC circuit can help.
Can Error 03 be caused by installation wiring errors?
Yes — if the signal wire terminals were connected incorrectly or swapped during installation, Error 03 will appear immediately on first startup. An installer returning to correct a wiring error should not charge for this visit.