Kolpak Walk-In Cooler Error Code EXTERNAL ALARM 3: Main AUX3 Input Active
EXTERNAL ALARM 3 means the Main AUX3 input is set to EXT ALARM and the digital input is active. The alarm comes from whatever is wired to AUX3, not from the controller. Press ENTER to silence it for an hour and identify the device.
Medium: an outside input is signaling a condition the controller cannot explain.
- Code
- EXTERNAL ALARM 3
- Maker
- Kolpak
- Equipment
- Walk-in coolers & freezers
- Applies to
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
What does Kolpak EXTERNAL ALARM 3 mean?
The third auxiliary input on the Main board of an ArcticFox controller is configured through AUX3 IN MODE. When that mode is EXT ALARM, the controller is told to treat a closed or open contact on AUX3 as an alarm condition. The controller reads the digital input and nothing more. If the input is active, the text alarm EXTERNAL ALARM 3 is placed in the Alarms menu and the display sounds. Because the device is chosen at installation, only the wiring records or a look at the terminal tell you what it is. The alarm remains as long as the input stays active, so an operator cannot clear it from the display. ENTER only quiets it for one hour. Once the connected device is corrected or the input is changed to a different mode, the alarm can end.
Affected models and control systems
ArcticFox OEM Controller with Deluxe Display on Kolpak walk-ins. This is the Main AUX3 input alarm, listed in the Alarms menu on page 16.
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 3 text in the Alarms menu
- Audible alarm from the display
- Connected equipment showing a tripped or alarm state
- Alarm back an hour after silencing
Possible causes
Likely causes — what usually sits behind EXTERNAL ALARM 3 on this control. A technician confirms which one it is before any part is replaced.
- Equipment on AUX3 reporting a real condition that needs attention
- AUX3 contact welded or stuck, holding the input active
- Mode left on EXT ALARM after an input was reassigned or removed
- Corroded or loosened terminal on the AUX3 wiring
Safe checks before calling for service
- Press ENTER to silence the alarm. It stays quiet for 1 hour and returns if AUX3 is still active.
- Find what is connected to AUX3 using any wiring label or the installation notes.
- Check that device from outside its cover for a warning lamp or tripped switch.
- Note the alarm text, the connected device, and how long the alarm has been active for the service call.
How a technician diagnoses EXTERNAL ALARM 3
- Check the AUX3 IN MODE setting on the Main controller.
- Locate the device on AUX3 and read its state.
- Measure the AUX3 input with a meter and compare with the device's contact position.
- Isolate the field wire to see whether the alarm clears.
- Repair or replace the failed device, or reset the mode to match the real wiring.
- Terminals on the Main board are inside the controller enclosure and carry power while the unit is running.
- Silencing a real safety input without understanding it can hide a condition the room depends on.
- Reassigning an input mode is a controller programming change and should be made against the installation record.
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
Is EXTERNAL ALARM 3 about the walk-in temperature?
Not directly. It reports a signal on AUX3. The device might be related to temperature, or to something else entirely.
Why does it come back after I press ENTER?
ENTER only silences it for one hour. If the AUX3 input is still active the alarm sounds again.
Should I disconnect the AUX3 wire?
No. The wire may belong to a monitoring device. Leave that to a technician.
Need help with Kolpak EXTERNAL ALARM 3?
A technician confirms the cause on site and gives you the price in writing before any work starts.