Kolpak Walk-In Cooler Error Code COMMUNICATION ERROR: Bonded Controllers
COMMUNICATION ERROR appears only on bonded controllers and means they have not communicated with each other for one minute or more. Press ENTER to silence the alarm for one hour. The manual gives no causes, so a technician needs to check the link between the controllers.
Medium: the controllers have lost their shared link, but the manual does not say cooling stops.
- Code
- COMMUNICATION ERROR
- Maker
- Kolpak
- Equipment
- Walk-in coolers & freezers
- Applies to
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
What does Kolpak COMMUNICATION ERROR mean?
Some Kolpak walk-ins use more than one ArcticFox controller bonded together so they can share information. Bonded controllers keep exchanging messages, and each one expects to hear from the other. If that exchange stops for one minute or longer, the controller shows the text alarm COMMUNICATION ERROR in the Alarms menu. The manual limits this alarm to bonded controllers, which means a single, stand-alone controller will not show it. The check runs continuously rather than at a set time. The alarm describes the link, not the temperature: it does not say which controller stopped talking or why. Refrigeration on each controller may carry on working from its own settings, but the shared behavior that bonding provides cannot be relied on while the link is down. The alarm sounds again after the one-hour silence if communication has not come back.
Affected models and control systems
ArcticFox OEM Controller with Deluxe Display on Kolpak walk-ins, in bonded controller setups only. The manual lists this alarm on page 16 and says it does not apply to controllers that are not bonded.
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
- COMMUNICATION ERROR text in the Alarms menu
- Audible alarm from the display
- Two controllers showing different information for the same room
- Alarm returning an hour after silencing
Possible causes
Likely causes — what usually sits behind COMMUNICATION ERROR on this control. A technician confirms which one it is before any part is replaced.
- Communication cable between the bonded controllers loose, cut, or pulled from its terminal
- One of the bonded controllers powered off or on a tripped circuit
- Communication wiring run too close to power wiring and picking up interference
- Bonding settings changed on one controller so the two no longer match
Safe checks before calling for service
- Look at the display on each bonded controller and note whether both are powered and showing normal readings.
- Press ENTER to silence the alarm. It stays quiet for 1 hour and sounds again if communication has not returned.
- Check that the breakers feeding both controllers are on. Do not open any panel or touch wiring.
- Record which controller shows the alarm, whether the other one shows it too, and when it began.
How a technician diagnoses COMMUNICATION ERROR
- Confirm both controllers are powered and read their status and bonding settings.
- Trace the communication cable between the controllers and check connections at both ends with power off.
- Measure voltage supply at each controller to rule out a brownout on one of them.
- Look for a damaged cable or a routing problem near power conductors.
- Restore the link, then watch the alarm for several minutes to confirm communication holds.
- Tracing the communication cable means opening control enclosures that are fed with line voltage.
- Bonding settings are programmed in the controller and a wrong entry can change how both units behave.
- Isolating a single bad controller in a bonded pair needs swap tests that only a trained technician should do.
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
Does this alarm mean my walk-in has stopped cooling?
Not necessarily. The alarm reports that the controllers lost contact for a minute or more. Each unit may still be cooling, so check the room temperature.
Why do I see this on only one controller?
The manual does not say. A technician can tell by checking whether the other controller also lost the link.
I have a single controller. Can I get this alarm?
No. The manual says it applies to bonded controllers only.
Need help with Kolpak COMMUNICATION ERROR?
A technician confirms the cause on site and gives you the price in writing before any work starts.