Polar King Walk-In Cooler Alarm T1 SUCTION SENSOR: Shorted or Open
T1 SUCTION SENSOR is an alarm on the KE2 evaporator control: the suction temperature sensor is shorted or open. The document lists it with no repair steps. Check that the box is holding temperature, clear the alarm once, and call for service if it comes back.
Medium: a sensor reading is lost, but the document describes no shutdown.
- Code
- T1 SUCTION SENSOR
- 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 T1 SUCTION SENSOR mean?
On the suction line of a walk-in's evaporator there is a temperature sensor that the KE2 Evaporator Efficiency board labels T1. The board checks that its signal looks like a real temperature. When the sensor wire is shorted, or the circuit is open, the board can no longer read it and records T1 SUCTION SENSOR in the Alarms Status Menu. The Combo Display shows the name; the Basic Display shows a red or yellow alarm light. The installation instructions list the alarm and its trigger, which is a shorted or open sensor, and nothing else: no cause, no reset other than the CLEAR ALARMS menu item, no effect on cooling. Suction temperature is normally one of the two readings used to work out superheat, so a lost T1 reading may make it hard for the board to judge how the evaporator is feeding.
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
- Alarm light on the Basic Display
- T1 SUCTION SENSOR in the Combo Display alarm list
- Superheat related alarms appearing at the same time
Possible causes
Likely causes — what usually sits behind T1 SUCTION SENSOR on this control. A technician confirms which one it is before any part is replaced.
- A sensor lead crushed under the suction line insulation
- A bulb that has slipped off the suction pipe
- A sensor plug corroded in the cold, damp evaporator area
Safe checks before calling for service
- Note the alarm color on the Basic Display or read the name on the Combo Display.
- Check the walk-in temperature with a thermometer.
- Use the CLEAR ALARMS menu item to clear it and see whether T1 SUCTION SENSOR returns.
- If it returns, write down when and the box temperature, and arrange service.
How a technician diagnoses T1 SUCTION SENSOR
- Read the alarm and note whether other alarms appear with it.
- Check the sensor mounting and insulation on the suction line.
- Measure the sensor resistance with the board disconnected and compare it with the temperature chart.
- Check the cable for a short or break between the sensor and the board.
- Replace the sensor if it reads open or shorted, then clear the alarm and confirm.
- Measuring the sensor means disconnecting the evaporator board, which has live control wiring. The suction line is part of the refrigerant circuit, and the sensor must be mounted and insulated correctly on it. Judging how the loss of T1 affects superheat control takes refrigeration knowledge.
How T1 SUCTION SENSOR differs from similar codes
T1 is the suction temperature sensor. T2, T3 and T4 are the return air, coil and auxiliary sensors on the same board.
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
What does T1 mean?
The document names it the suction temperature sensor.
Will clearing the alarm repair the sensor?
No. It only clears the stored alarm.
Could T1 SUCTION SENSOR cause other alarms?
Possibly, since the board uses suction temperature for superheat. The document does not say.
Need help with Polar King T1 SUCTION SENSOR?
A technician confirms the cause on site and gives you the price in writing before any work starts.