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Error code reference

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

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

U-Line codesU-Line ice maker codes

Left zone temperature is -10° under 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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What L Temp Lo 12H+ means on a U-Line ice maker

The L Temp Lo 12H+ error code on a U-Line ice maker indicates that the left zone temperature has fallen and remained at least 10 degrees Fahrenheit below the configured set point for a continuous period exceeding 12 hours. This is a sustained thermal fault, meaning the unit has been unable to maintain the target temperature in the left zone for an extended duration. The 12-hour threshold distinguishes this from a transient temperature drop and signals that a persistent mechanical or electrical failure is preventing proper temperature regulation.

The primary systems involved in this fault are the refrigeration circuit and the airflow system. The compressor is responsible for circulating refrigerant and maintaining the cooling cycle, while the evaporator fan moves conditioned air across the evaporator coil and into the left zone. If either of these components fails, or if the relays and DC outputs controlling them malfunction, the zone will lose its ability to hold temperature at the set point. A failed relay may prevent the compressor or fan motor from receiving the voltage needed to operate, even if the components themselves are mechanically intact.

Diagnosis should begin by checking the compressor for operation, verifying that the evaporator fan is spinning at the correct speed, and inspecting the associated relays and DC control outputs. A compressor that is running but not pumping effectively, a fan motor drawing abnormal current, or a relay that is stuck open or closed can all produce this sustained temperature deviation. Wiring connections, control board outputs, and component resistance values should be measured to isolate the specific point of failure.

Source: manufacturer service documentation.

Common causes of L Temp Lo 12H+

  1. 01

    Compressor failure or reduced output

    Part replacement

    A compressor that has failed mechanically or is not pumping refrigerant efficiently can cause uncontrolled temperature drops in the zone. Listen for unusual sounds and verify the compressor is cycling on and drawing proper current.

  2. 02

    Faulty relay controlling the compressor or fan

    Part replacement

    A failed relay can send incorrect signals to the compressor or evaporator fan, causing them to run continuously or at incorrect intervals. Inspect and test each relay associated with the left zone cooling circuit for proper switching behavior.

  3. 03

    Evaporator fan motor failure

    Part replacement

    If the evaporator fan motor stops operating or runs at reduced speed, airflow across the evaporator coil is disrupted and the zone temperature can drop well below the set point. Check that the fan is spinning freely and receiving correct DC voltage from the control board.

  4. 04

    DC output failure on the control board

    Part replacement

    A failed DC output on the main control board may prevent proper voltage from reaching the compressor or fan motor, causing the refrigeration system to operate outside normal parameters. Measure the DC outputs at the board to confirm they are within specification.

  5. 05

    Temperature sensor misreading

    Part replacement

    A defective or out-of-calibration temperature sensor in the left zone may report incorrect readings to the control board, triggering this fault even if actual temperatures are closer to normal. Verify sensor resistance values match expected specifications for the measured temperature.

See the test procedure for each cause

Frequently asked questions about L Temp Lo 12H+

What does L Temp Lo 12H+ mean on a U-Line ice_maker?
This code means the left zone temperature has been at least 10 degrees below the set point for more than 12 consecutive hours. It indicates a sustained failure in the refrigeration or airflow system rather than a brief temperature swing. The most common causes involve the compressor, evaporator fan, or the relays and DC outputs that control them. A technician should inspect these components to determine the root cause.
Can I fix the L Temp Lo 12H+ error myself on a U-Line ice maker?
Some basic checks, such as verifying the evaporator fan is spinning and listening for compressor operation, can be done by a knowledgeable homeowner. However, testing relays, measuring DC control board outputs, and diagnosing compressor performance requires electrical testing equipment and refrigeration knowledge. Most repairs that resolve this code will involve replacing a component and should be performed by a qualified appliance technician.
Will resetting the U-Line ice maker clear the L Temp Lo 12H+ error?
A reset may temporarily clear the error code from the display, but it will not resolve the underlying mechanical or electrical fault causing the temperature deviation. If the compressor, fan, or relay responsible for the problem is not repaired or replaced, the error will return once the unit monitors temperatures for another 12-hour period. Resetting without fixing the root cause is not a recommended solution.
Is it safe to continue using my U-Line ice maker while the L Temp Lo 12H+ code is active?
Continuing to run the unit while this fault is active is not advisable. A sustained temperature 10 degrees or more below the set point can indicate a refrigeration system problem that may worsen over time and could affect ice quality or lead to further component damage. The ice produced during this fault condition may not meet normal standards, and the unit should be inspected before continued use.
How much does it cost to repair a U-Line ice maker showing the L Temp Lo 12H+ error?
Repair costs vary depending on which component has failed. Relay replacements are typically on the lower end of the cost range, while evaporator fan motor or control board repairs fall in a mid-range cost category. Compressor replacement is generally the most expensive repair, potentially ranging from several hundred dollars to over a thousand dollars including labor. A technician diagnosis will be needed to determine the specific failed component and provide an accurate estimate.

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