Ako AL3 Error Code

What does Ako AL3 mean?

AL3 is the minimum temperature alarm on AKO controllers that support multiple alarm thresholds (AL1 through AL6 series). It indicates the temperature measured by the control probe has dropped below the minimum limit set in parameter A2. This alarm is used to detect over-cooling or freezing conditions in applications where the setpoint has a defined lower bound.

Symptoms

• AL3 appears on the display alternating with the current temperature.
• Alarm relay activates and audible alarm sounds.
• Temperature reading confirms the space is below the A2 minimum alarm threshold.
• Product may be at risk of freeze damage if the condition persists.
• Compressor continues to run unless a separate low-temperature cut-out is fitted.

Common causes

• Setpoint (SP) configured too low, allowing the compressor to pull the space below the minimum alarm threshold.
• Compressor running continuously due to a stuck contactor or failed thermostatic control.
• Expansion valve opening too wide causing excessive cooling.
• Ambient temperature is very low in an uncontrolled environment, causing the space to cool below minimum.
• A2 minimum alarm parameter set too close to the setpoint, generating nuisance alarms.

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Diagnostic steps

1. Confirm the reading is genuine with an independent thermometer

   Verify the displayed temperature against a calibrated reference thermometer placed in the cold room. Rule out a probe fault before assuming the space is genuinely below minimum.

2. Check compressor run status

   Determine whether the compressor is running continuously. If it is, check the control setpoint (SP) and differential (dIF) against the A2 minimum alarm value to confirm the setpoint allows temperatures below the minimum alarm limit.

3. Review A2 and A3 parameter settings

   Enter the parameter menu and confirm A2 (minimum temperature alarm) and A3 (alarm activation delay) are set correctly for the application. Adjust if the alarm threshold is incorrectly configured.

4. Inspect the compressor contactor and expansion valve

   Check that the compressor contactor opens correctly on demand and that the expansion valve is not stuck open. A continuously running compressor or over-feeding expansion valve drives temperatures below minimum.

5. Reset the alarm and monitor

   After correcting the root cause, reset the alarm and observe the temperature trend to confirm it stabilizes within the acceptable range.

When to call a professional

Call a licensed refrigeration technician if AL3 is caused by a stuck expansion valve, failed compressor contactor, or refrigerant overcharge — all of which require refrigerant system expertise. If product has frozen and food safety compliance needs to be assessed, involve a qualified inspector in addition to the technician.