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Error code reference

Frigidaire Air Conditioner Error Code ES

Evaporator thermistor sensor has failed.

Frigidaire codesFrigidaire air conditioner codes

Evaporator thermistor sensor has failed.

First step from the service manual

Check/replace the evaporator thermistor.

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

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What ES means on a Frigidaire air conditioner

The ES error code on a Frigidaire air conditioner indicates that the control board has detected a failure in one or more of the unit's temperature sensors. These sensors, typically thermistors, send resistance-based readings to the control board so it can regulate cooling cycles, fan speed, and compressor operation. When a sensor falls outside its expected resistance range or sends no signal at all, the board flags ES and halts normal operation to prevent running the system blind without accurate temperature data.

For homeowners, this means the air conditioner's internal monitoring system has lost its ability to accurately read temperatures inside the unit or in the room. Think of the sensor as the AC's thermometer. Without a working sensor, the unit cannot make smart decisions about when to cool, when to stop, or whether the system is overheating. This is why the unit may stop cooling or display the code instead of operating normally.

Because sensor failures can involve the sensor itself, the wiring connecting it to the control board, or the control board's sensor input circuit, diagnosis requires a technician with the proper tools to measure thermistor resistance and trace the circuit. Frigidaire directs users to contact an Authorized Frigidaire Service Center as the first step.

Source: manufacturer service documentation.

Common causes of ES

  1. 01

    Failed thermistor (temperature sensor)

    Part replacement

    The thermistor itself has degraded or shorted internally, sending a resistance value outside the acceptable range or no signal at all. This is the most common trigger for the ES code and requires replacing the sensor.

  2. 02

    Damaged or disconnected sensor wiring harness

    Part replacement

    The wiring between the thermistor and the control board can become corroded, pinched, or disconnected, interrupting the signal. The sensor may still be functional but the control board reads an open or short circuit.

  3. 03

    Moisture or corrosion at the sensor connector

    Wiring / connection

    Condensation inside the unit can reach the sensor connector pins, causing corrosion that increases resistance or breaks continuity. In some cases cleaning the connector resolves the fault, but corroded connectors often need replacement.

  4. 04

    Control board sensor input circuit failure

    Part replacement

    If the thermistor and its wiring test within spec but the ES code persists, the sensor input circuit on the control board itself may have failed. This is the least common cause but requires control board replacement.

See the test procedure for each cause

Frequently asked questions about ES

What does the ES error code mean on a Frigidaire air conditioner?
ES means the control board has detected a sensor failure. The sensor involved is typically a thermistor, a small component that measures temperature and sends that data to the control board. When the sensor fails or its circuit is broken, the board displays ES and interrupts normal operation because it can no longer regulate the cooling cycle accurately.
Can I still use my Frigidaire air conditioner when ES is showing?
Running the unit while ES is active is not recommended. Without a functioning temperature sensor, the control board cannot monitor conditions accurately, which means the compressor and fan may not cycle correctly. Continued operation could lead to inadequate cooling, potential overheating of internal components, or compressor damage. Power the unit off and schedule a service call.
How do I fix the ES error code on my Frigidaire air conditioner?
Frigidaire's specified first step is to contact an Authorized Frigidaire Service Center. A technician will use a multimeter to test the thermistor's resistance against the manufacturer's spec, inspect the wiring harness for damage or corrosion, and confirm whether the fault is in the sensor, its wiring, or the control board's input circuit. This is not a repair that can be resolved by resetting the unit alone.
How much does it cost to repair the ES error code on a Frigidaire air conditioner?
If the fix is a thermistor replacement, parts are typically inexpensive, often under thirty dollars, but labor and a service call fee will make up most of the cost. If the control board needs replacement, expect higher parts costs depending on the model. Getting a diagnosis from an Authorized Frigidaire Service Center first will clarify which component has failed before committing to a repair cost.
Will resetting my Frigidaire air conditioner clear the ES code?
A power reset may temporarily clear the display, but if the sensor or its wiring has physically failed, the ES code will return as soon as the unit restarts and the control board runs its sensor check. A reset does not fix the underlying hardware fault. If the code comes back after a reset, the unit needs professional diagnosis.

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