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Error code reference

U-Line Ice Maker Error Code L Temp Hi 12H+

Left zone temperature is +10° over set point for over 12 hours.

U-Line codesU-Line ice maker codes

Left zone temperature is +10° over set point for over 12 hours.

First step from the service manual

Check compressor, evaporator fan and related relays and DC outputs.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
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What L Temp Hi 12H+ means on a U-Line ice maker

The L Temp Hi 12H+ error code on a U-Line ice maker indicates that the left zone temperature has been running 10 degrees or more above the programmed set point continuously for over 12 hours. This is a sustained thermal fault, meaning the unit has had ample time to self-correct through normal refrigeration cycles and has failed to do so. The 12-hour threshold eliminates false alarms from brief door openings or heavy load conditions, so when this code appears, a genuine mechanical or electrical failure is almost certainly present in the refrigeration or airflow system.

The primary systems involved are the compressor, the evaporator fan, and the relay and DC output circuits that control them. If the compressor is not running or is running inefficiently, refrigerant is not being circulated and the evaporator cannot absorb heat from the cabinet. Similarly, if the evaporator fan is not moving air across the evaporator coil and into the left zone, cooling capacity is severely reduced even if the compressor is operating correctly. Both of these components depend on relay outputs and DC control signals from the main control board to function.

Diagnosis should begin by confirming whether the compressor and evaporator fan are physically running. Check the associated relays for proper switching and verify that DC output voltages from the control board are within expected parameters. A failed relay can cut power to either component even when the board is issuing the correct command. A seized or failed evaporator fan motor, a compressor that hums but does not start, or a control board with a failed output circuit are the most common root causes of this sustained high-temperature condition.

Source: manufacturer service documentation.

Common causes of L Temp Hi 12H+

  1. 01

    Failed or seized evaporator fan motor

    Part replacement

    If the evaporator fan motor is not running, cold air cannot be circulated through the left zone, causing temperatures to rise well above the set point. Listen for fan operation and check for DC voltage at the motor terminals to confirm.

  2. 02

    Compressor not starting or running

    Part replacement

    A compressor that fails to start or runs but does not build pressure will cause the entire refrigeration cycle to fail. Check whether the compressor is receiving power via its relay and whether it hums, runs, or stays silent.

  3. 03

    Faulty relay or failed DC output from control board

    Part replacement

    The compressor and evaporator fan rely on relay switching and DC output signals from the control board. A burned or stuck relay, or a failed board output, can cut power to these components even when the board appears to be functioning otherwise.

  4. 04

    Refrigerant loss or restriction

    Part replacement

    A refrigerant leak or a blockage in the refrigeration circuit can prevent the evaporator from absorbing heat, causing persistent high temperatures in the left zone. This typically shows as a compressor running continuously without the cabinet cooling down.

  5. 05

    Poor airflow or blocked vents

    Wiring / connection

    Ice buildup on the evaporator or debris blocking internal air passages can restrict airflow enough to cause prolonged temperature rise. Inspect the evaporator coil for frost accumulation and verify that all internal vents are unobstructed.

See the test procedure for each cause

Frequently asked questions about L Temp Hi 12H+

What does L Temp Hi 12H+ mean on a U-Line ice_maker?
This code means the left zone temperature has been 10 degrees or more above the set point for over 12 continuous hours. It indicates a sustained cooling failure rather than a brief temperature spike. The compressor, evaporator fan, and their associated relays and DC control outputs are the primary components to inspect. Until the root cause is corrected, the unit will not maintain proper temperature or produce ice reliably.
Can I fix the L Temp Hi 12H+ error myself on a U-Line ice maker?
Some basic checks are within reach of a knowledgeable DIYer, such as verifying the evaporator fan is spinning, checking that the unit is not packed too tightly against a wall restricting airflow, and inspecting for ice buildup on the evaporator. However, diagnosing relay outputs, DC control board signals, and compressor function typically requires a multimeter and familiarity with refrigeration systems. Refrigerant-related issues must be handled by a certified technician.
Will resetting my U-Line ice maker clear the L Temp Hi 12H+ error?
A reset may temporarily clear the error code from the display, but it will not resolve the underlying mechanical or electrical problem causing the temperature fault. If the compressor, evaporator fan, or control relay has failed, the code will return once the unit has run long enough to detect the same high-temperature condition. The root cause must be repaired for the error to stay cleared.
Is it safe to keep using my U-Line ice maker when the L Temp Hi 12H+ error is showing?
Continuing to run the unit with this error is not recommended. A zone that has been overtemperature for 12 or more hours means ice quality and food safety standards are not being met. Ice produced during this condition may be undersized or partially melted. It is best to stop using the ice maker and have it serviced before relying on it again.
How much does it cost to repair a U-Line ice maker showing the L Temp Hi 12H+ error?
Repair costs depend on which component has failed. An evaporator fan motor replacement typically falls in the range of 100 to 250 dollars in parts and labor. Control board or relay repairs can range from 150 to 400 dollars or more depending on the specific board. Compressor replacement is the most expensive scenario, often ranging from 300 to 600 dollars or higher including labor. A diagnostic service call is usually needed first to confirm the exact cause.

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