Ako E5

What does Ako E5 mean?

The controller has received an active signal on a digital input that is configured as a severe external alarm (parameter P10 or P11 set to 3). Unlike a standard external alarm, this condition is classified as severe, halts normal regulation in some configurations, activates the alarm relay and audible buzzer, and requires manual reset after the triggering signal disappears.

Symptoms

• E5 displays on the controller screen.
• Alarm relay and audible alarm activate immediately.
• Regulation or compressor output stops depending on configuration.
• Alarm persists after the digital input signal clears until manually acknowledged.

Common causes

• External device wired to the digital input has signaled a fault (most common: high-pressure switch, door contact, or remote alarm panel).
• Digital input parameter P10 or P11 incorrectly set to 3 when external device is not connected, causing a spurious alarm.
• Broken or shorted wiring on the digital input circuit.
• Power transient or electromagnetic interference triggering a false alarm on the digital input.

Diagnostic steps

1. 01

   Identify the external device wired to the digital input

   Check controller wiring diagrams to determine which external device is connected to the digital input configured as severe alarm (P10 or P11 = 3). Common devices include high-pressure switches, oil pressure switches, or remote alarm contacts.

2. 02

   Inspect the external device status

   Check whether the connected device (e.g., high-pressure switch) has genuinely tripped. Resolve the underlying fault on the external device before expecting the alarm to clear.

3. 03

   Check digital input wiring continuity

   With power off, measure continuity from the external device terminals to the controller digital input terminals. Repair any open or short circuits in the wiring run.

4. 04

   Verify P10/P11 parameter settings

   Enter the parameter menu and confirm that P10 or P11 is intentionally set to 3 (severe external alarm). If no external alarm device is connected, change the parameter to the appropriate value to prevent spurious alarms.

5. 05

   Reset the alarm after resolving the cause

   Once the external fault is cleared, reset the controller alarm manually per the AKO manual procedure. Confirm E5 no longer appears and normal regulation resumes.

When to call a professional

Call a licensed technician if the severe alarm is triggered by a high-pressure or oil-pressure safety switch, as these indicate potential refrigeration system failures requiring refrigerant system diagnosis. If the external device is a fire or gas detection system, follow your facility's emergency protocol and involve qualified safety personnel before resetting the alarm.