U-Line Refrigerator Error Code Temp Lo 12H+

The Temp Lo 12H+ code means the temperature in one of the refrigerator zones has been more than 10°F below the set point for over 12 hours. The unit is overcooling in that zone, not failing to cool. The most common causes are a faulty thermistor sending an incorrect reading or a zone valve that is stuck in the open position.

A reset may temporarily clear the error code, but it will return if the underlying cause is not corrected. Because the fault requires 12 hours of sustained overcooling to trigger, simply resetting the unit without addressing the thermistor, connections, or zone valve will likely result in the code reappearing. Fix the root cause before relying on a reset.

Repair costs vary depending on the faulty component. Thermistor replacement is typically the least expensive fix, with parts generally ranging from around $20 to $60 and labor adding to that total. Zone valve replacement tends to cost more, with parts ranging from roughly $50 to $150 depending on the model, plus labor. A control board replacement, if required, is usually the most expensive outcome and can run several hundred dollars including installation.

Start by inspecting the thermistor connections for moisture, corrosion, or looseness, and clean or reseat them as needed. Then check the thermistor resistance to confirm it matches expected values for the current temperature. Next, verify that the zone valve opens and closes correctly during operation. If either the thermistor or zone valve is defective, replacing the faulty component should resolve the overcooling condition.

Because this error indicates the zone is running colder than the set point rather than warmer, food spoilage is not the primary concern. However, temperatures that are too low can damage certain foods, freeze beverages, or harm wine stored in that zone. Check the actual temperature of the compartment and remove any items that could be harmed by freezing temperatures while you diagnose the problem.