Polar King Walk-In Cooler Alarm LOW SUPERHEAT: Below Lower Limit
LOW SUPERHEAT is an alarm on the KE2 evaporator control: superheat is below the lower limit. The document gives no repair steps. It can mean liquid refrigerant reaching the compressor, so have a technician check promptly if it repeats.
High: low superheat can send liquid refrigerant to the compressor.
- Code
- LOW SUPERHEAT
- Maker
- Polar King
- Equipment
- Walk-in coolers & freezers
- Applies to
- Polar King walk-in coolers/freezers with KE2 Evaporator Efficiency Evap OEM board (Basic Display / Combo Display)
What does Polar King LOW SUPERHEAT mean?
The KE2 Evaporator Efficiency board compares the temperature of the refrigerant leaving the evaporator with the boiling temperature at the measured suction pressure, and the difference is superheat. When superheat drops below the lower limit, the Alarms Status Menu lists LOW SUPERHEAT. On the Combo Display you see the name; on the Basic Display only a red or yellow light. The installation instructions give the trigger and note that alarms can be cleared with the CLEAR ALARMS menu item. They give no causes and no actions. In general, too little superheat means the coil is overfeeding, so refrigerant can leave it as liquid. That is hard on a compressor, which is meant to pump vapor. The document does not say this directly, so treat it as background for why the alarm should be checked rather than ignored.
Affected models and control systems
Polar King walk-in coolers and freezers fitted with the KE2 Evaporator Efficiency Evap OEM board, with either the Basic Display or the Combo Display. The alarm is listed in the Alarms Status Menu, which is view only, on page 14 of the KE2 installation instructions.
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
- Red or yellow light on the Basic Display
- LOW SUPERHEAT on the Combo Display
- Frost or ice running back along the suction line
- Compressor sounding rough
Possible causes
Likely causes — what usually sits behind LOW SUPERHEAT on this control. A technician confirms which one it is before any part is replaced.
- An expansion device that is feeding too much refrigerant
- A coil sensor or suction sensor reading higher than real
- Refrigerant overcharge in the system
- A fan on the evaporator that is not moving enough air
Safe checks before calling for service
- Look at the suction line near the compressor, from outside, for heavy frost or sweat.
- Check the box temperature with a thermometer.
- Clear the alarm with CLEAR ALARMS and see whether it comes back.
- If it returns, write down the frost you saw and the box temperature and arrange service quickly.
How a technician diagnoses LOW SUPERHEAT
- Read the alarm and the superheat value.
- Measure suction pressure and line temperature with gauges and thermometers.
- Check the evaporator fans and coil for ice.
- Verify the sensors against reference readings.
- Adjust or correct the feed to restore superheat within limits, then confirm.
- Liquid refrigerant returning to a compressor can damage it, so the diagnosis cannot be delayed or guessed at. Gauges and certification are needed to measure and adjust a refrigerant circuit. The suction sensors and the board carry live control wiring.
How LOW SUPERHEAT differs from similar codes
LOW SUPERHEAT is the lower-limit alarm, the mirror of HIGH SUPERHEAT. The two need opposite corrections.
Technical reference
- Document
- KE2 Evaporator Efficiency Installation Instructions N.1.1 (posted on polarking.com Downloads as ke2-installation.pdf; authored by KE2 Therm Solutions)
- Edition
- N.1.1 July 2015
- Models / control
- Polar King walk-in coolers/freezers with KE2 Evaporator Efficiency Evap OEM board (Basic Display / Combo Display)
- Section
- Alarms Status Menu (view only), p. 14 (Alarm Status Menu listed p. 13)
- 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 Polar King walk-in cooler & freezer error codes
Why is low superheat a concern?
Too little superheat can let liquid refrigerant reach the compressor, which it is not built to handle.
Can I keep running the walk-in?
Check the box temperature, but if the alarm repeats, arrange service soon.
Does CLEAR ALARMS stop it?
It clears the stored alarm only.
Need help with Polar King LOW SUPERHEAT?
A technician confirms the cause on site and gives you the price in writing before any work starts.