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Error code reference

Fisher & Paykel Refrigerator Error Code INV-18

Inverter PCB over temperature.

Fisher & Paykel codesFisher & Paykel refrigerator codes

Inverter PCB over temperature.

First step from the service manual

Replace inverter module.

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

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What INV-18 means on a Fisher & Paykel refrigerator

INV-18 is an inverter PCB over temperature fault on Fisher & Paykel refrigerators. The inverter module is responsible for controlling the variable-speed compressor, converting DC voltage to the precise AC waveform needed to drive the compressor motor at different speeds. When the inverter PCB itself reaches an unsafe operating temperature, the control system triggers this fault code to protect the board and compressor from heat-related damage.

Overheating of the inverter PCB can result from several conditions. Restricted airflow around the inverter module is a common contributor, particularly if the refrigerator has been installed in a confined space or if condenser components are clogged with dust and debris. A failing or seized condenser fan motor can also reduce airflow across the inverter, causing heat to build up on the board. In some cases, internal component degradation on the inverter PCB itself causes it to generate excessive heat during normal operation.

Because the inverter module integrates power switching components that operate at elevated temperatures under normal load, any condition that reduces heat dissipation can push the board beyond its thermal limits. The recommended first diagnostic step is replacement of the inverter module, which reflects that by the time this fault is logged, the board may already have sustained thermal stress sufficient to compromise its reliability even if the root cause is addressed separately.

Source: manufacturer service documentation.

Common causes of INV-18

  1. 01

    Failed inverter PCB

    Part replacement

    The inverter board itself may have degraded internal components that cause it to overheat during operation. Since replacement of the inverter module is the primary diagnostic step, a faulty board is the most direct cause to address.

  2. 02

    Restricted airflow around the inverter module

    Wiring / connection

    Inadequate ventilation in the installation space can prevent the inverter from dissipating heat properly. Check that clearance requirements around the refrigerator are met and that no objects are blocking airflow to the inverter area.

  3. 03

    Condenser fan motor failure

    Part replacement

    A failing or seized condenser fan motor reduces airflow across the inverter and condenser, allowing heat to accumulate on the board. Check that the condenser fan spins freely and runs when the compressor is commanded on.

  4. 04

    Clogged condenser coils or vents

    Wiring / connection

    Dust and debris buildup on the condenser coils restricts heat dissipation and raises ambient temperature around the inverter module. Inspect and clean the condenser area if significant debris is present.

  5. 05

    High ambient temperature at installation location

    Wiring / connection

    If the refrigerator is located in a hot environment such as a garage or utility room with poor ventilation, the inverter may operate outside its thermal limits. Verify the installation environment is within the appliance's rated ambient temperature range.

See the test procedure for each cause

Frequently asked questions about INV-18

What does INV-18 mean on a Fisher & Paykel refrigerator?
INV-18 indicates that the inverter PCB has exceeded its safe operating temperature. The inverter module controls the variable-speed compressor, and this fault is triggered to protect the board and compressor from heat damage. The refrigerator will not run normally while this fault is active. Replacement of the inverter module is the recommended first step.
Can I fix INV-18 myself or do I need a technician?
Some contributing factors, such as cleaning condenser coils or improving ventilation around the unit, can be addressed without professional help. However, replacing the inverter PCB involves working with high-voltage components and is best handled by a qualified appliance technician. Attempting inverter replacement without proper training and safety precautions carries a serious risk of electric shock.
Is it safe to keep using my refrigerator when INV-18 is showing?
No, you should not continue operating the refrigerator normally while this fault is active. The inverter has detected an over-temperature condition and the compressor will not run reliably, meaning food safety could be compromised. Continued operation without addressing the fault risks further damage to the inverter and compressor.
Will resetting the refrigerator clear the INV-18 error?
A power reset may temporarily clear the fault code, but if the underlying cause of the overheating has not been resolved, the fault will return once the inverter reaches its temperature threshold again. Resetting without repairing the root cause is not a lasting solution and could allow further thermal damage to occur.
How much does it cost to repair an INV-18 error on a Fisher & Paykel refrigerator?
Repair costs vary depending on the specific cause and whether the inverter module needs replacement. Parts and labor for an inverter module replacement typically fall in the range of $200 to $500 or more, depending on your location and the technician's rates. If the fault is caused only by a blocked condenser or ventilation issue, the cost can be significantly lower.

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