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Error code reference

U-Line Freezer Error Code (L) (R) Evap T Open

Left or right evaporator thermistor circuit open.

U-Line codesU-Line freezer codes

Left or right evaporator thermistor circuit open.

First step from the service manual

Inspect evaporator thermistor connection. Replace if necessary.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What (L) (R) Evap T Open means on a U-Line freezer

The (L) (R) Evap T Open error on a U-Line freezer indicates that the thermistor circuit monitoring either the left or right evaporator has gone open. An open circuit means the control board is receiving no signal from that thermistor, which differs from a shorted condition where resistance reads near zero. The evaporator thermistor is a negative temperature coefficient (NTC) sensor whose resistance changes predictably with temperature, allowing the control board to monitor evaporator coil temperature and regulate the refrigeration cycle. When the circuit is open, resistance reads as infinite, and the board cannot determine evaporator temperature.

The most common causes of an open thermistor circuit are a failed thermistor sensor, a disconnected or damaged wiring harness, or a corroded connector at the thermistor plug. Thermistors can crack or fail internally over time, especially in the freeze-thaw cycling environment of an evaporator compartment. Wiring and connectors in that area are also subject to moisture, ice accumulation, and mechanical stress from service access, all of which can interrupt continuity.

Diagnosis should begin at the thermistor connector. Inspect the plug for corrosion, bent pins, or loose seating. If the connection appears intact, use a multimeter to measure thermistor resistance across the sensor leads. An open reading confirms thermistor failure and replacement is required. If resistance reads within the expected NTC range for the ambient temperature, trace the wiring back toward the control board to locate a break or damaged section of the harness.

Source: manufacturer service documentation.

Common causes of (L) (R) Evap T Open

  1. 01

    Failed evaporator thermistor

    Part replacement

    The thermistor sensor itself has failed internally, breaking the circuit and causing an open reading. Confirm with a multimeter by measuring resistance across the sensor leads, an open or infinite reading confirms the sensor needs replacement.

  2. 02

    Disconnected thermistor connector

    Wiring / connection

    The wiring connector at the thermistor plug has come loose, especially after a service visit or due to ice buildup pushing on the harness. Inspect the connector and reseat it firmly to restore the circuit.

  3. 03

    Corroded or damaged connector pins

    Wiring / connection

    Moisture in the evaporator compartment can corrode the thermistor connector pins over time, creating resistance or an open condition at the plug. Inspect the pins visually and clean or replace the connector as needed.

  4. 04

    Broken or pinched wiring harness

    Part replacement

    The wiring between the thermistor and the control board can develop a break due to mechanical stress, ice accumulation, or improper routing after service. Check the harness for any visible damage, cuts, or pinch points.

  5. 05

    Control board input failure

    Part replacement

    In rare cases, the thermistor input circuit on the control board itself may have failed, causing the board to report an open even when the sensor and wiring are intact. This is typically identified only after the sensor and wiring have been confirmed good.

See the test procedure for each cause

Frequently asked questions about (L) (R) Evap T Open

What does (L) (R) Evap T Open mean on a U-Line freezer?
This error means the control board has detected an open circuit on either the left or right evaporator thermistor. The thermistor is a temperature sensor that monitors the evaporator coil, and an open circuit means the board is receiving no signal from it. This can be caused by a failed sensor, a loose connector, or a break in the wiring harness. The freezer may not regulate temperature correctly while this fault is active.
Can I fix the (L) (R) Evap T Open error myself?
A knowledgeable DIYer can start by inspecting and reseating the thermistor connector, which sometimes resolves the error without parts. If the connector is secure, testing the thermistor with a multimeter is the next step to determine whether the sensor needs replacement. Wiring repairs and control board replacement are generally better handled by a qualified technician.
Is it safe to keep using my freezer while this error is displayed?
Continuing to use the freezer with an open evaporator thermistor error is not recommended for food safety. The control board relies on this sensor to regulate the cooling cycle, and without accurate temperature data, the freezer may not maintain proper temperatures. Check the actual compartment temperature with a standalone thermometer and consider moving frozen food if cooling performance is compromised.
How much does it cost to repair the (L) (R) Evap T Open error on a U-Line freezer?
If only the thermistor sensor needs replacement, parts typically range from around $15 to $50 depending on the specific model, plus labor if a technician is involved. If the control board is at fault, board replacement can cost significantly more, generally in the range of $150 to $400 or higher for parts alone. A diagnostic visit from an appliance technician usually adds $75 to $150 to the total cost.
Will resetting my U-Line freezer clear the (L) (R) Evap T Open error?
A power reset may temporarily clear the error display, but the code will return if the underlying fault in the thermistor circuit has not been corrected. The control board detects the open circuit condition each time it polls the sensor, so the error will reappear during normal operation. Resetting should only be done as part of a diagnostic process, not as a standalone fix.

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