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Error code reference

LG Hvac Error Code 23

Inverter DC link voltage too low.

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Inverter DC link voltage too low.

First step from the service manual

Verify proper 208/240V AC feeding unit; voltage must be 193-253V AC. Use appropriate service manual to verify if PCB has failed.

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

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What 23 means on a LG hvac

Error code 23 on an LG HVAC system indicates that the DC link voltage within the inverter circuit has dropped below the acceptable operating threshold. The inverter converts incoming AC power into DC, then modulates that DC voltage to drive the variable-speed compressor motor. When the DC bus voltage falls too low, the control board detects the condition and shuts the system down to prevent damage to the inverter components, compressor drive circuitry, and the compressor itself.

The most common root cause is insufficient AC supply voltage reaching the unit. LG specifies that the incoming supply must remain within 193 to 253 volts AC during operation. Voltage at the low end of this range or below can result from undersized wiring, a weak utility feed, high-resistance connections at breakers or disconnect blocks, or shared circuits with heavy loads. Measuring true supply voltage at the unit's terminal block under load conditions is the critical first diagnostic step, as voltage can appear adequate at idle but sag significantly when the compressor attempts to start.

If the supply voltage measures within the 193 to 253 volt AC specification and the fault persists, attention shifts to the inverter PCB itself. The PCB contains the rectifier bridge, capacitor bank, and IGBT modules that comprise the DC link circuit. A failure in any of these components can cause the DC bus to read low even with proper AC input. Capacitor degradation is a common internal PCB failure mode that reduces the DC link's ability to hold voltage under load. In this scenario, PCB replacement is typically required.

Source: manufacturer service documentation.

Common causes of 23

  1. 01

    Low or unstable AC supply voltage

    Wiring / connection

    The incoming supply voltage is below the required 193V AC minimum. This can result from a weak utility feed, voltage sag during compressor startup, or problems at the utility transformer serving the property.

  2. 02

    High-resistance wiring or connection issues

    Wiring / connection

    Loose terminals at the breaker, disconnect block, or unit terminal strip cause a voltage drop under load. Check all connections for tightness, corrosion, or heat damage and measure voltage directly at the unit's terminals while the system is attempting to operate.

  3. 03

    Undersized or degraded supply wiring

    Wiring / connection

    Wire gauge that is too small for the circuit run length creates excessive resistance and voltage drop, particularly when the compressor loads the circuit. Verify wire gauge against the unit's nameplate amperage and the total circuit length.

  4. 04

    Failed or tripped main disconnect or breaker

    Part replacement

    A breaker that has partially tripped or a disconnect fuse that has blown on one leg can reduce the supply to the unit, resulting in low DC link voltage. Check both legs of the supply with a voltmeter and confirm the breaker is fully seated.

  5. 05

    Faulty inverter PCB

    Part replacement

    If supply voltage is confirmed within the 193 to 253V AC range and the fault persists, the inverter PCB itself may have failed internally, often due to degraded DC link capacitors or a damaged rectifier or IGBT module that prevents the DC bus from reaching proper voltage.

See the test procedure for each cause

Frequently asked questions about 23

What does 23 mean on a LG hvac?
Error code 23 means the inverter's DC link voltage has dropped below the minimum acceptable level. The system monitors the internal DC bus voltage that powers the variable-speed compressor drive, and it shuts down when that voltage is too low. The required AC supply to the unit must be between 193 and 253 volts AC. The fault can be caused by a low supply voltage or a failed inverter PCB.
Can I fix error code 23 on my LG HVAC myself?
Some basic checks are within reach of a knowledgeable homeowner, such as confirming the circuit breaker is fully seated and not tripped. However, measuring voltages at the unit's terminal block and diagnosing the inverter PCB require a multimeter, electrical safety knowledge, and familiarity with HVAC systems. Most repairs beyond the breaker check should be handled by a licensed HVAC technician.
Is it safe to keep running my LG HVAC when error code 23 appears?
No. Error code 23 causes the system to shut down as a protective measure, and the unit will not operate normally while this fault is active. Attempting to force operation with low DC link voltage risks damaging the inverter components and compressor, which are expensive to replace. Leave the system off until the root cause is diagnosed and corrected.
How much does it cost to repair error code 23 on an LG HVAC?
Repair cost depends on the cause. If the issue is a loose connection or a tripped breaker, the cost may be limited to a service call fee, typically in the range of $75 to $150. If the inverter PCB has failed and requires replacement, parts and labor combined can range from $400 to over $1,000 depending on the specific unit model and local labor rates.
Will resetting the LG HVAC clear error code 23?
Resetting the unit by cycling power may temporarily clear the fault display, but the error will return if the underlying cause is not corrected. If the supply voltage is consistently below 193V AC or the inverter PCB is faulty, the system will detect the low DC link voltage again and re-enter the fault state. A reset is useful for confirming the fault is repeatable, but it is not a fix.

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