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Error code reference

LG Hvac Error Code 89

Flex Multi LMUxxxHV units DIP Switch 3 configuration error on outdoor PCB.

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Flex Multi LMUxxxHV units DIP Switch 3 configuration error on outdoor PCB.

First step from the service manual

DIP Switch 3 on outdoor PCB needs to be in OFF position.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What 89 means on a LG hvac

Error code 89 on LG Flex Multi LMUxxxHV outdoor units indicates a DIP switch configuration fault on the outdoor printed circuit board (PCB). Specifically, DIP Switch 3 on the outdoor PCB has been detected in the wrong position, triggering this error and preventing normal system operation. The Flex Multi platform relies on DIP switch settings to define how the outdoor unit is configured within a multi-zone system, and an incorrect setting on Switch 3 causes the control board to flag a configuration mismatch.

The root cause is almost always a physical switch position error rather than a component failure. DIP Switch 3 must be set to the OFF position on the outdoor PCB for the LMUxxxHV series to operate correctly. This misconfiguration can occur during initial installation if the technician does not verify the factory default switch positions, or after a PCB replacement if the replacement board was previously programmed for a different unit type or application. In some cases, vibration over time can cause a switch to shift position, though this is less common.

Diagnosing this error begins with locating the DIP switch bank on the outdoor unit PCB and confirming the state of Switch 3. If it is in the ON position, switching it to OFF and cycling power to the unit should clear the fault. No parts are typically required to resolve this error unless the PCB itself is damaged or the switch mechanism is physically broken and cannot be toggled reliably.

Source: manufacturer service documentation.

Common causes of 89

  1. 01

    DIP Switch 3 left in ON position during installation

    Wiring / connection

    The most frequent cause is that DIP Switch 3 on the outdoor PCB was not set to OFF during initial installation. A technician should visually inspect the DIP switch bank on the outdoor board and confirm Switch 3 is in the OFF position.

  2. 02

    Incorrect switch position after PCB replacement

    Wiring / connection

    If the outdoor PCB was recently replaced, the replacement board may have come pre-set for a different unit configuration, leaving DIP Switch 3 in the ON position. Always verify all DIP switch positions against the unit requirements after installing a new board.

  3. 03

    Switch position shifted due to vibration

    Wiring / connection

    Prolonged vibration from compressor operation can occasionally cause a DIP switch to move from its intended position. Check whether any other switches have also shifted position while inspecting Switch 3.

  4. 04

    Damaged or faulty DIP switch mechanism

    Part replacement

    In rare cases, the physical DIP switch on the PCB may be damaged and unable to maintain the correct OFF position. If the switch will not stay in the OFF position or appears physically broken, PCB replacement may be required.

See the test procedure for each cause

Frequently asked questions about 89

What does 89 mean on a LG hvac?
Error code 89 on an LG Flex Multi LMUxxxHV outdoor unit indicates a DIP switch configuration error on the outdoor PCB. Specifically, DIP Switch 3 has been detected in the wrong position and needs to be set to OFF. The system will not operate normally until this switch is corrected. This is a configuration fault, not a component failure in most cases.
How do I fix error code 89 on my LG Flex Multi outdoor unit?
Locate the DIP switch bank on the outdoor unit PCB and confirm that DIP Switch 3 is in the OFF position. If it is ON, switch it to OFF and then cycle power to the outdoor unit. The error should clear once the board reads the correct switch configuration. If the error persists after correcting the switch position, the PCB itself may need further inspection.
Is error code 89 on an LG multi-zone system a safety concern?
Error code 89 is a configuration fault rather than a safety-critical electrical or refrigerant issue. The system is designed to prevent operation when it detects a DIP switch mismatch, which protects the unit from running in an unsupported configuration. However, since accessing the outdoor PCB requires opening the unit cabinet, this work should be performed by a qualified HVAC technician.
Will resetting the unit clear error code 89 on an LG hvac?
A simple power reset will not permanently clear error code 89 because the fault is tied to the physical position of DIP Switch 3 on the outdoor PCB. Each time the unit powers on, it reads the switch position, and the error will return if Switch 3 remains in the ON position. The switch must be physically moved to OFF before the error will clear on restart.
How much does it cost to fix error code 89 on an LG Flex Multi unit?
If the fix requires only repositioning DIP Switch 3, the cost is limited to a service call fee, typically in the range of $75 to $150 depending on your location and technician. If the DIP switch or PCB is physically damaged and the board requires replacement, parts and labor costs can range from $300 to $700 or more. In most cases, this error is resolved quickly without any parts needed.

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