Kolpak Walk-In Cooler Error Code COMP SEQ COMM ERROR: Sequencer Link Lost
COMP SEQ COMM ERROR means the controller is set to communicate with a Compressor Sequencer but no communication is detected. The link between the two is not working. Press ENTER to silence the alarm for one hour and have a technician check the connection.
Medium: the sequencer link is down and compressor staging may not work as intended.
- Code
- COMP SEQ COMM ERROR
- Maker
- Kolpak
- Equipment
- Walk-in coolers & freezers
- Applies to
- ArcticFox OEM Controller with Deluxe Display (Kolpak walk-ins)
What does Kolpak COMP SEQ COMM ERROR mean?
Some installations use a Compressor Sequencer to stage compressors on a rack or group, and the ArcticFox controller can be set to talk to it. When that setting is on, the controller expects to hear from the sequencer. If it detects no communication, it posts the text alarm COMP SEQ COMM ERROR in the Alarms menu. Two things have to be true for the alarm: the controller has to be set up for a sequencer, and the link has to be silent. The manual does not list causes or give a time, so the exact timing is not known. The alarm is about the link, not the compressors' pressure or temperature. If the link is down, the staging that the sequencer provides may not work as intended. It sounds again after the one-hour silence unless communication is restored or the setting is corrected.
Affected models and control systems
ArcticFox OEM Controller with Deluxe Display on Kolpak walk-ins set to communicate with a Compressor Sequencer. The manual lists this alarm 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
- COMP SEQ COMM ERROR text in the Alarms menu
- Audible alarm from the display
- Compressors not staging as expected
- Alarm sounding again after silencing
Possible causes
Likely causes — what usually sits behind COMP SEQ COMM ERROR on this control. A technician confirms which one it is before any part is replaced.
- Communication cable to the Compressor Sequencer loose, damaged, or disconnected
- Compressor Sequencer powered off or tripped
- Controller set to use a sequencer on a system that does not have one
- Communication wiring picking up noise from nearby power wiring
Safe checks before calling for service
- Press ENTER to silence the alarm. It stays quiet for 1 hour and sounds again if the link is not restored.
- Check whether the equipment that holds the sequencer has power and shows its normal indicator lights.
- Do not open panels or touch communication wiring.
- Tell the technician if a sequencer was ever installed and whether the alarm appeared after power work.
How a technician diagnoses COMP SEQ COMM ERROR
- Confirm the controller setting that enables sequencer communication.
- Verify the Compressor Sequencer is powered and operating.
- Check the communication cable and terminations at both ends with power off.
- Test the supply voltage on both devices.
- Restore the link, or correct the setting if there is no sequencer, and confirm the alarm stays clear.
- Checking communication terminals means opening enclosures that carry line voltage.
- Whether a sequencer should be connected is a question for the installation records.
- Changing the communication setting changes how compressors are controlled.
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 is a Compressor Sequencer?
It is a device that stages compressors. The manual lists this alarm for controllers set to talk to one.
My system has no sequencer. Why the alarm?
The controller may be set to expect one. A technician can check and correct the setting.
Is this the same as COMMUNICATION ERROR?
No. COMMUNICATION ERROR is for bonded controllers. This one is for the Compressor Sequencer link.
Need help with Kolpak COMP SEQ COMM ERROR?
A technician confirms the cause on site and gives you the price in writing before any work starts.