LG Multi V VRF Fan Board Issue
LG Multi V VRF Fan Board Communication Error (105 / 105.1) in NYC
A 105 (or 105.1) code on an LG Multi V VRF outdoor unit means the main inverter PCB has lost communication with the outdoor fan PCB inside that outdoor frame -- distinct from CH106 (a fan motor electrical fault the fan board itself detects and reports) and from CH104/CH204 (communication loss between separate outdoor frames or a Heat Recovery box).
What We Check First
105.1 means the main PCB isn't receiving a response from the fan PCB in the Master outdoor frame -- 105.2/105.3 indicate the same fault on a Slave frame in multi-module systems.
A blown fan PCB fuse, loose or corroded wiring between the main and fan PCBs, low control voltage, and a failed fan IPM are the documented common causes.
Quick Answer
An LG Multi V VRF outdoor unit throwing 105 (or 105.1) has lost communication between the main inverter PCB and the outdoor fan PCB within that outdoor frame. Documented common causes include a blown 3.15A fuse on the fan PCB, loose or corroded communication wiring between the two boards, control voltage dropping below 13.5V DC, or a failed fan IPM (intelligent power module) that draws down the board's power supply. A severe fan motor short can also cause this code indirectly, by blowing the fan PCB's fuse -- a more typical direct motor fault instead throws CH106.
Common Causes
Blown fan PCB fuse
The outdoor fan PCB carries a low-current fuse (typically 3.15A/250V). If it blows, the board loses control power and stops communicating entirely, raising 105/105.1.
Loose or corroded communication wiring
The communication harness between the main inverter PCB and the fan PCB can loosen, disconnect, or corrode, breaking the link the main board depends on to poll the fan board.
Failed fan IPM pulling down board power
The fan PCB's intelligent power module drives the outdoor BLDC fan motor. A short circuit or thermal failure in the IPM can pull down the board's internal low-voltage supply or blow its fuse, taking the fan board offline.
LG Error Codes For This Issue
Codes below are informational — a code alone doesn't confirm the fix, and resetting power without addressing the underlying fault often just delays the problem.
105 / 105.1 (105.2, 105.3 on Slave frames)
What it means: Verified: communication failure between the main inverter PCB and the outdoor fan PCB within a single outdoor frame -- the suffix identifies which frame (Master = .1) in a multi-module system.
When service is needed: Service is needed to check the fan PCB fuse, inspect communication wiring between the boards, verify control/DC link voltage, and test the fan IPM.
DIY-Safe Checks vs. Call for Service
DIY-Safe
- Noting whether the outdoor fan is spinning at all before the technician arrives, which helps distinguish a communication-link fault from a motor that's clearly locked or seized.
Professional Required
- Testing continuity on the fan PCB fuse and replacing it if blown, after checking for a shorted component that caused it to blow.
- Inspecting and re-terminating communication wiring between the main and fan PCBs.
- Testing the fan IPM with a diode-mode resistance check and replacing the fan PCB and/or fan motor as diagnosed.
FAQ
What does LG Multi V VRF error code 105 or 105.1 mean?
It means the main inverter PCB has lost communication with the outdoor fan PCB in that outdoor frame. The .1 suffix identifies the Master frame; .2 and .3 identify Slave frames in multi-module systems.
Is a 105.1 error the same as a CH106 fan error?
No -- CH106 means the fan board is communicating normally but has detected an electrical fault in the fan motor itself (overcurrent or a locked rotor). 105.1 means the fan board has stopped communicating entirely, most often from a blown fuse, bad wiring, or a failed power module.
Can a bad fan motor cause a 105.1 error instead of CH106?
Yes, indirectly -- a severe short circuit in the motor windings can draw enough current through the fan board to blow its fuse or destroy its power supply, which knocks the board fully offline and triggers 105.1 instead of the motor-specific CH106 code.
Recent Work
Recent LG Repairs
Real LG jobs documented across New York City.
Reported Issue
It was 105.1 (fan board error )
Technical Resolution
Both the fan board and the inverter board were replaced.
Related
Schedule LG Service
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An LG Multi V VRF outdoor unit throwing 105 (or 105.1) has lost communication between the main inverter PCB and the outdoor fan PCB within that outdoor frame. Documented common causes include a blown 3.15A fuse on the fan PCB, loose or corroded communication wiring between the two boards, control voltage dropping below 13.5V DC, or a failed fan IPM (intelligent power module) that draws down the board's power supply. A severe fan motor short can also cause this code indirectly, by blowing the fan PCB's fuse -- a more typical direct motor fault instead throws CH106.