Nor-Lake LogiTemp Walk-In Error Code A1A: AUX1 Sensor Shorted or Open

What does Nor-Lake error code A1A mean?

The KE2 Evap OEM controller on a Nor-Lake Split-Pak walk-in has several auxiliary sensor inputs, and AUX1 is the first of them. Depending on how the system was set up, such an input carries an extra sensor for a job like a second box probe or a monitored point. The controller keeps checking that the input gives a believable temperature. A sensor that has failed shorted reads far below the possible range, and one that has failed open reads far above it, and in either case the controller shows A1A. Nothing about the main box sensors changes, so the cooler or freezer usually keeps working, but whatever depended on AUX1 is running without it. Which function that is depends on how Aux Input 1 was set up on the controller, and that is a question the installer's setup answers, not the display. The alarm clears when the reading becomes usable again, which can happen if a loose connector is reseated.

Affected models and control systems

This applies to the LogiTemp / KE2 Evap OEM controller on Nor-Lake Split-Pak systems with A1 refrigerants, in walk-in coolers and freezers. Other controller generations number their alarms differently.

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

• A1A on the display along with a colored alarm LED
• The box itself holds temperature normally
• An extra monitored point that no longer reports
• Alarm that comes and goes with door traffic or vibration

Possible causes

Listed in Nor-Lake's documentation

• The sensor wired to the AUX1 input
• Its connector and wire run
• The AUX1 input on the controller
• How Aux Input 1 was set up on the controller

Other likely causes — what usually sits behind error code A1A on this control. A technician confirms which one it is before any part is replaced.

• Sensor cable pinched against the evaporator housing or a door frame
• Ice around the connector in a freezer lifting the contacts
• Sensor left connected after the monitored point was removed, so the input now reads open

Safe checks before calling for service

How a technician diagnoses error code A1A

1. Read A1A and the LED state, and confirm which function Aux Input 1 serves.
2. Check the sensor and its reading against a reference thermometer.
3. With power off, inspect the wire run and connector for pinch, ice or corrosion.
4. Measure the sensor resistance and compare with its temperature.
5. Test the AUX1 input if the sensor tests good, and replace only the part that fails.

How error code A1A differs from similar codes

A2A and A3A are the same alarm for AUX2 and AUX3, so the three codes point at different sensors.

Technical reference

Document

LogiTemp Electronic Controller System Operations Manual (171527 Rev. A), Alarms & Notifications List pp. 47-51

Edition

171527 Rev. A, 2025 (Refrigerated Solutions Group)

Models / control

LogiTemp / KE2 Evap OEM (Split-Pak systems, A1 refrigerants)

Section

Alarms & Notifications List, printed pp. 48-52; Troubleshooting Tables from p. 52

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.