Kolpak Walk-In Cooler Error Code EXTERNAL ALARM 1: Main AUX1 Input Active
EXTERNAL ALARM 1 means the Main AUX1 input is set to EXT ALARM and the digital input is active. That is an outside device telling the controller something is wrong. Press ENTER to silence it for one hour and find out what is wired to AUX1.
Medium: an outside input is reporting a condition, and the controller cannot say how serious it is.
- Code
- EXTERNAL ALARM 1
- Maker
- Kolpak
- Equipment
- Walk-in coolers & freezers
- Applies to
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
What does Kolpak EXTERNAL ALARM 1 mean?
The Main board has auxiliary inputs. AUX1 IN MODE decides what the input does, and when it is set to EXT ALARM the controller treats the input as an alarm line from some outside device. That device might be a high-temperature switch, a power monitor, or any contact someone chose to wire in. The controller does not know what the device is. It only reads whether the digital input is active. When the input is active, the text alarm EXTERNAL ALARM 1 appears in the Alarms menu. So the alarm tells you about the thing connected to AUX1, not about the controller itself. The check is continuous, and the alarm stays as long as the input stays active. Pressing ENTER silences the sound for one hour, but the cause is on the outside device and has to be dealt with there.
Affected models and control systems
ArcticFox OEM Controller with Deluxe Display on Kolpak walk-ins. This is the Main controller AUX1 input, listed in the Alarms menu on page 16. The Display has its own matching alarm, DISP EXTERNAL ALARM 1.
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
- EXTERNAL ALARM 1 text in the Alarms menu
- Audible alarm until ENTER is pressed
- Whatever device is wired to AUX1 showing its own warning light
- Alarm sounding again after the one-hour silence
Possible causes
Likely causes — what usually sits behind EXTERNAL ALARM 1 on this control. A technician confirms which one it is before any part is replaced.
- Outside device wired to AUX1 has changed state and is reporting a real condition
- Contact on that device stuck closed or open so the input stays active
- AUX1 IN MODE left on EXT ALARM for an input that nothing is meant to use
- Loose or shorted wire on the AUX1 input terminal
Safe checks before calling for service
- Press ENTER to silence the alarm. It is silent for 1 hour and sounds again if the input is still active.
- Find out what the installer wired to AUX1. A label at the controller or in the job paperwork often says.
- Look at that device for a warning light or tripped state, from outside any panel.
- Give the technician the alarm text and the device name, plus whether the device shows a problem.
How a technician diagnoses EXTERNAL ALARM 1
- Read the Main AUX1 IN MODE setting and confirm it is set to EXT ALARM.
- Identify the device connected to AUX1 and check its own status.
- Measure the input at the AUX1 terminals with a meter to see whether it is truly active.
- Disconnect the field wiring briefly and see whether the alarm clears, which separates a wiring problem from a real alarm.
- Fix the outside device or the wiring, or set the input mode correctly if nothing should be connected.
- Measuring AUX1 terminals means working inside the controller enclosure with the unit powered.
- The outside device might be a safety or monitoring switch, and tampering with it can hide a real problem.
- Changing AUX1 IN MODE is a programming change that has to match what the installer wired.
Technical reference
- Document
- ArcticFox Deluxe Display - Original Instructions, Installation, Operation and Maintenance Manual
- Edition
- Part No. 500002385-4, 5/23
- Models / control
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
- Section
- ArcticFox OEM Controller - Alarms Menu, p.16
- 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 Kolpak walk-in cooler & freezer error codes
What does the number 1 mean?
It refers to the Main AUX1 input. The manual lists matching alarms for AUX2 and AUX3.
Can I ignore this alarm?
Only after you know what is connected to AUX1. The alarm may be a warning from a real device.
Is this different from DISP EXTERNAL ALARM 1?
Yes. This one comes from the Main AUX1 input. The DISP version comes from AUX1 on the Display.
Need help with Kolpak EXTERNAL ALARM 1?
A technician confirms the cause on site and gives you the price in writing before any work starts.