Danfoss A11

What does Danfoss A11 mean?

A11 means no refrigerant type has been selected on a Danfoss EKC controller. Pressure-to-temperature conversions and the superheat calculation depend on the refrigerant setting, so the controller cannot regulate correctly until a refrigerant is chosen. On the EKC 313 the manual notes that parameter o30 must be set to define the refrigerant. The alarm relay activates at high priority.

Symptoms

• Display shows A11 when the alarm is recalled.
• Controller will not regulate superheat or pressure correctly.
• Pressure-to-temperature readings are absent or meaningless.
• Alarm relay is active at high priority until a refrigerant is set.

Common causes

• The refrigerant-selection parameter (o30) has not been set.
• Settings were reset to factory defaults, clearing the refrigerant choice.
• A new or replacement controller was installed without commissioning.
• Configuration was cleared during a software update or fault.

Diagnostic steps

1. 01

   Recall the alarm

   Press the top button to display A11, then press again to cancel the active alarm.

2. 02

   Open the refrigerant parameter

   Enter the menu and navigate to parameter o30, the refrigerant-selection setting on the EKC controller.

3. 03

   Select the correct refrigerant

   Choose the refrigerant that matches the system from the controller's numbered list (for example R134a, R404A, R744). If the gas is not listed, define its constants via the AKM tool as described in the manual.

4. 04

   Confirm the alarm clears

   After setting o30, verify A11 disappears and the controller resumes pressure-to-temperature conversion and regulation.

When to call a professional

Selecting the wrong refrigerant produces incorrect superheat and pressure calculations, which can damage the compressor. If you are unsure which refrigerant the system uses, or the gas must be defined manually through its constants, have a refrigeration technician set parameter o30 and verify regulation. Correct refrigerant configuration is a commissioning step that should be confirmed by someone trained on the equipment.