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Error code reference

Frigidaire Air Conditioner Error Code F1

Indoor ambient temperature sensor is open or short-circuited.

Frigidaire codesFrigidaire air conditioner codes

Indoor ambient temperature sensor is open or short-circuited.

First step from the service manual

Check if the wiring terminal between indoor ambient temperature sensor and controller is loosened or poorly contacted.

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

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What F1 means on a Frigidaire air conditioner

The F1 error code on a Frigidaire air conditioner indicates a fault with the indoor ambient temperature sensor, specifically that the sensor circuit is either open (broken or disconnected) or short-circuited. This sensor is a thermistor, a resistive component whose electrical resistance changes predictably with temperature. The control board reads this resistance to determine the room temperature and regulate cooling cycles accordingly. When the circuit is open, the board receives no signal, and when it is short-circuited, it receives an out-of-range or erroneous reading. Either condition causes the controller to flag an F1 fault and may prevent normal operation.

The most common entry point for diagnosing this fault is the wiring terminal connecting the sensor to the control board. Vibration during shipping or normal operation can loosen these connectors, and corrosion or moisture intrusion can cause poor contact even when connections appear intact. A loose or corroded terminal will produce an intermittent or absent signal that the board interprets as an open or shorted circuit.

If the wiring connections check out, the thermistor itself may have failed. A failed thermistor will show either infinite resistance (open circuit) or near-zero resistance (short circuit) when measured with a multimeter, rather than the expected resistance value for ambient temperature. Damage to the wiring harness between the sensor and the board, such as pinched or frayed insulation causing a short to ground, is another possible cause. In less common cases, the control board input circuit itself may be faulty, though this is typically diagnosed after ruling out the sensor and wiring.

Source: manufacturer service documentation.

Common causes of F1

  1. 01

    Loose or poorly seated wiring terminal

    Wiring / connection

    The connector between the ambient temperature sensor and the control board may have worked loose over time. Inspect the terminal for any visible gaps, corrosion, or pins that are not fully seated, and firmly reseat the connector.

  2. 02

    Failed indoor ambient temperature sensor (thermistor)

    Part replacement

    The thermistor itself may have failed in an open or shorted state. Testing with a multimeter should show a resistance value consistent with room temperature. Infinite or near-zero resistance confirms the sensor has failed and needs replacement.

  3. 03

    Damaged wiring harness

    Part replacement

    The wiring between the sensor and the control board may be pinched, frayed, or have damaged insulation causing an unintended short or open circuit. Visually inspect the full length of the wire for obvious damage.

  4. 04

    Corrosion at the sensor connector

    Wiring / connection

    Moisture exposure can corrode the terminal pins at the sensor connector, increasing resistance to the point where the board cannot read a valid signal. Check for green or white oxidation on the connector pins.

  5. 05

    Faulty control board input circuit

    Part replacement

    If the sensor and all wiring test correctly, the input circuit on the control board that reads the sensor signal may be damaged. This is the least likely cause and should be investigated only after the sensor and harness are confirmed good.

See the test procedure for each cause

Frequently asked questions about F1

What does F1 mean on a Frigidaire air conditioner?
The F1 code means the indoor ambient temperature sensor circuit has been detected as open or short-circuited. This sensor is a thermistor that tells the control board the current room temperature. The fault prevents the unit from receiving a valid temperature reading, which can disrupt normal cooling operation. The issue may be in the sensor itself, its wiring, or the connector terminal.
Can I fix the F1 error on my Frigidaire air conditioner myself?
In many cases, yes. Start by unplugging the unit and checking that the wiring connector between the temperature sensor and the control board is fully seated and free of corrosion. If reconnecting the terminal clears the fault, no further repair may be needed. If the sensor itself has failed, replacing a thermistor is a straightforward repair for someone comfortable working with small electrical components.
Will resetting my Frigidaire air conditioner clear the F1 error?
A power reset may temporarily clear the F1 code, but the error will return if the underlying fault is not corrected. If the sensor circuit is still open or shorted after the reset, the control board will detect the problem again and redisplay the code. A reset is useful for confirming whether the fault is intermittent, but it does not substitute for diagnosing and repairing the root cause.
Is it safe to run my Frigidaire air conditioner with an F1 error?
Running the unit with an active F1 fault is not recommended. Without a valid ambient temperature reading, the control board cannot regulate the cooling cycle properly, which may result in the unit not cooling, short-cycling, or potentially running without the normal temperature-based shutoff controls. It is best to address the fault before resuming regular use.
How much does it cost to repair the F1 error on a Frigidaire air conditioner?
If the fix is simply reseating a loose connector, there is no parts cost involved. Replacing a failed ambient temperature sensor thermistor is generally an inexpensive repair, with parts typically ranging from a few dollars to around twenty dollars depending on the model. If the control board itself needs replacement, costs increase significantly, often ranging from fifty to over one hundred fifty dollars for the part alone, plus any labor if a technician is involved.

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