Nor-Lake Walk-In Error Code CoA: Bonded Controllers Not Talking
CoA appears on Nor-Lake LogiTemp walk-ins when bonded controllers have had no communication for one minute or more. Each controller keeps working on its own settings, but the shared control stops. Check that every controller has power, keep a thermometer in the box and call us if CoA does not clear.
Medium: shared control is lost while each controller keeps cooling on its own.
- Code
- CoA
- Maker
- Nor-Lake
- Equipment
- Walk-in coolers & freezers
- Applies to
- LogiTemp / KE2 Evap OEM (Split-Pak systems, A1 refrigerants)
What does Nor-Lake error code CoA mean?
On Nor-Lake Split-Pak systems, KE2 Evap OEM controllers can be bonded so that they share information about the box. A bonded group acts like one controller with several faces, which keeps defrosts and fans in step. The controllers check the link all the time. When there has been no communication for one minute or more, the display shows CoA on the Basic Display. Each controller carries on with its own settings, so the walk-in may keep cooling, but the coordinated functions are lost and the units may behave differently from each other. The alarm describes a broken link, not a failed unit. It points at the communication wiring between the controllers, the connectors and terminals at each controller, power to each controller, or the bond settings on both. Because the group needs matching settings, a controller that was swapped or reset can break the bond even when the wiring is fine, and that is worth telling the technician.
Affected models and control systems
This applies to bonded LogiTemp / KE2 Evap OEM controllers on Nor-Lake Split-Pak systems with A1 refrigerants, in walk-in coolers and freezers.
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
- CoA on the Basic Display
- Evaporators defrosting at different times
- One controller display dark
- Box temperature still in range
Possible causes
Listed in Nor-Lake's documentation
- Communication wiring between the controllers
- Connectors and terminals at each controller
- Power to each controller
- The bond settings on both controllers
Other likely causes — what usually sits behind error code CoA on this control. A technician confirms which one it is before any part is replaced.
- Controller replaced or reset so the bond no longer matches
- Communication wire disturbed during other electrical work in the box
- Moisture in a terminal block in a cold, wet area
Safe checks before calling for service
- Write down the code and which walk-in shows it.
- Check that each controller display is lit and has power.
- Keep a thermometer in the box and note the reading twice a shift.
- Call us to schedule service if CoA does not clear on its own.
How a technician diagnoses error code CoA
- Read CoA on each controller and see which are powered.
- Confirm the box temperature and the defrost state.
- Inspect the communication wiring and terminals.
- Compare the bond settings on both controllers.
- Rebuild the bond or replace the wire or controller after testing.
- Each controller is fed from line voltage and must be opened with power off.
- Bond settings need to match on both controllers, which takes system data.
- Communication wiring is often routed through walls and ceilings.
How error code CoA differs from similar codes
CoA is a one-minute loss between bonded controllers, while CLL concerns lead and lag units. The two are set up differently.
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.
Related Nor-Lake walk-in cooler & freezer error codes
Will the walk-in keep cooling with CoA?
Usually yes, since each controller keeps its own settings. Still, watch the temperature.
Why does CoA wait a minute?
The controller allows short gaps in communication before it raises the alarm.
Can I rebond the controllers myself?
Please do not. Bond settings must match, and a wrong change can make it worse.
Need help with Nor-Lake error code CoA?
A technician confirms the cause on site and gives you the price in writing before any work starts.