True Refrigerator Error Code uLi: Low Voltage Alarm
ULi on a True commercial refrigerator with a Danfoss ERC control is a low voltage alarm: the supply voltage is too low. The manual lists it as uLi or uLo. Check that the unit is on its own properly rated outlet, and call a technician if the code returns.
Medium: the unit may keep running, but low supply voltage can stress the compressor.
- Code
- ULi
- Maker
- True
- Equipment
- Reach-in refrigerators
- Applies to
- TRUE commercial refrigeration appliances with Carel, Danfoss (ERC, ETC), Dixell and LAE display controls
What does True error code ULi mean?
ULi is the low voltage alarm on the Danfoss ERC control. The control monitors its supply voltage while the refrigerator is plugged in. If the voltage falls below the limit the control accepts, it flags the condition on the display as uLi so the operator can see that the electrical supply, not the refrigeration system, is the problem. The manual's code table lists the display text as Low voltage alarm and notes that the supply voltage is too low, with the code printed as uLi or uLo. It gives no causes, no limit values and no reset steps.
Affected models and control systems
True lists uLi in the Display Code Definitions for the Danfoss ERC and ETC family of controls on its commercial refrigeration units. Carel, Dixell and LAE displays appear in the same section with different codes. The manual prints the code as uLi or uLo, so either spelling can appear.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- ULi or uLo on the display
- Compressor struggling to start or cycling on and off
- Lights or other equipment on the same circuit dimming
Possible causes
Likely causes — what usually sits behind error code ULi on this control. A technician confirms which one it is before any part is replaced.
- Supply voltage reaching the control is too low
- Refrigerator sharing a circuit with a heavy load such as a fryer, dishwasher or space heater
- Extension cord or power strip dropping voltage between the wall and the unit
- Loose or corroded plug or receptacle causing a voltage drop under load
Safe checks before calling for service
- Make sure the refrigerator plugs directly into a wall outlet, not an extension cord or power strip.
- Turn off other large equipment on the same circuit and see whether uLi clears.
- Look at the plug and outlet for heat marks or a loose fit; if the plug is warm, unplug it and stop.
- Do not open electrical panels. If the display returns to a normal temperature reading, watch it through a full compressor cycle.
- Write down which equipment was running when the code appeared and the time of day, for the technician.
How a technician diagnoses error code ULi
- Read the code and history, then measure voltage at the outlet with the unit running and idle.
- Check the branch circuit for load from other equipment and for a voltage drop at the receptacle.
- Inspect the cord and plug for damage or heating.
- Measure voltage at the unit's terminals during compressor start.
- Check start parts and compressor current if low voltage is confirmed at the unit.
- Have the electrical supply corrected before replacing refrigeration parts.
- Measuring voltage under load and tracing a voltage drop means working with live 115 V or 208-230 V circuits.
- A weak circuit may need an electrician to correct wiring or add a dedicated line.
- Repeated low-voltage starts can damage the compressor, so the starting parts and current need testing with a meter.
How error code ULi differs from similar codes
The manual's Low voltage alarm label applies to uLi. A matching high voltage code is not listed for this controller in the entry we hold.
Technical reference
- Document
- Commercial Refrigeration General Control Guide
- Edition
- TEC_TM_001 | REV. C | EN, 09/3/2025, P#811072
- Models / control
- TRUE commercial refrigeration appliances with Carel, Danfoss (ERC, ETC), Dixell and LAE display controls
- Section
- Electronic Control (with Display) - Display Code Definitions: Carel p. 74, Danfoss ERC/ETC p. 87, Dixell p. 96, LAE p. 110
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related True reach-in refrigerator error codes
Can I run the refrigerator with uLi showing?
It is better not to leave it running for long. Low voltage strains the compressor, so move perishable food if the code stays.
Will uLi clear on its own?
It can once the supply returns to normal. If the cause is a shared or overloaded circuit, it will come back whenever the load repeats.
Is uLi the same as uLo?
The manual prints the code as uLi or uLo for the same low voltage alarm, so treat them as one condition.
Need help with True error code ULi?
A technician confirms the cause on site and gives you the price in writing before any work starts.