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Error code reference

Haier Air Conditioner Error Code F25

Discharge temperature sensor failure (outdoor)

Haier codesHaier air conditioner codes

Discharge temperature sensor failure (outdoor). Outdoor LED1 flashes 13 times.

First step from the service manual

Check connector connection; if normal, check thermistor resistance; if normal, replace PCB.

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

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What F25 means on a Haier air conditioner

The F25 error code on a Haier air conditioner indicates a failure in the discharge temperature sensor located on the outdoor unit. This sensor, also called a discharge thermistor, monitors the temperature of the refrigerant leaving the compressor. Accurate discharge temperature readings are critical for protecting the compressor from overheating and for allowing the control board to regulate system operation safely. When the outdoor PCB detects a signal from this sensor that falls outside the expected resistance range, it triggers the F25 fault and signals the condition by flashing LED1 on the outdoor unit 13 times.

The discharge thermistor is a negative temperature coefficient (NTC) resistor, meaning its resistance decreases as temperature rises. If the sensor circuit reads an open circuit, a short, or a resistance value that does not correspond to any valid temperature, the control board interprets this as a sensor failure. The fault can originate from three distinct locations: the physical connector between the sensor wiring harness and the outdoor PCB, the thermistor itself, or the outdoor PCB.

Diagnosis follows a clear sequence. First, inspect the connector at the outdoor PCB for corrosion, looseness, or damaged pins and reseat it firmly. If the connection is intact, measure the thermistor resistance with a multimeter and compare the reading against the temperature-resistance chart for the sensor. A reading that is open, shorted, or inconsistent with ambient temperature indicates a failed thermistor. If both the connector and thermistor check out as normal, the outdoor PCB is the likely cause and will need replacement.

Source: manufacturer service documentation.

Common causes of F25

  1. 01

    Loose or corroded sensor connector

    Wiring / connection

    The wiring harness connector linking the discharge thermistor to the outdoor PCB can work loose over time or develop corrosion, causing an intermittent or open circuit. Inspect the connector visually and reseat it firmly to see if the fault clears.

  2. 02

    Failed discharge thermistor

    Part replacement

    The NTC thermistor itself can fail open or short internally, producing a resistance reading that is outside the valid range for any temperature. Measure resistance with a multimeter and compare against the sensor specification to confirm a failed thermistor.

  3. 03

    Damaged sensor wiring

    Part replacement

    The wiring between the thermistor and the outdoor PCB can suffer physical damage from vibration, rodents, or UV exposure, resulting in an open or shorted circuit. Inspect the full length of the sensor wire for visible damage or pinching.

  4. 04

    Faulty outdoor PCB

    Part replacement

    If the connector and thermistor both test as normal, the outdoor control board may be misreading the sensor signal due to a failed input circuit. Board replacement is indicated only after the sensor and wiring have been ruled out.

See the test procedure for each cause

Frequently asked questions about F25

What does F25 mean on a Haier air_conditioner?
F25 indicates a discharge temperature sensor failure on the outdoor unit. The outdoor control board is not receiving a valid signal from the thermistor that monitors refrigerant temperature leaving the compressor. The outdoor LED1 will flash 13 times to signal this specific fault. The system will not operate normally until the fault is resolved.
Can I fix the F25 error myself?
A homeowner can safely inspect and reseat the sensor connector on the outdoor unit, which is the first recommended diagnostic step. However, measuring thermistor resistance and replacing the thermistor or outdoor PCB requires basic electrical knowledge and a multimeter. If you are not comfortable working with electrical components, a qualified HVAC technician should perform the diagnosis and repair.
Is it safe to keep running the air conditioner with an F25 error?
No, you should not attempt to bypass or ignore the F25 fault. The discharge temperature sensor protects the compressor from running under dangerously high refrigerant temperatures. Operating without a functioning sensor removes that protection and can result in compressor damage, which is a costly repair.
How much does it cost to repair an F25 error on a Haier air conditioner?
Cost depends on the failed component. Reseating a loose connector costs nothing beyond a service call fee. A replacement discharge thermistor is generally an inexpensive part, with total repair costs typically in the range of $75 to $200 including labor. If the outdoor PCB requires replacement, costs can range from $200 to $600 or more depending on the unit model and local labor rates.
Will resetting the air conditioner clear the F25 error?
A power reset may temporarily clear the fault display, but the F25 code will return if the underlying problem with the sensor, connector, or PCB has not been corrected. A reset is not a repair. The connector, thermistor resistance, and board should be checked in sequence before assuming the issue is resolved.

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