Irinox A16 Error Code

What does Irinox A16 mean?

The MULTIFRESH NEXT control has detected that the defrost termination probe RV5 (NTC-type) is faulty, out of range, or open-circuit. RV5 monitors evaporator temperature to signal when defrost is complete. If this probe is unavailable the controller cannot reliably terminate the defrost cycle, potentially leading to incomplete defrosting or flooding of the evaporator. The alarm auto-resets when a valid signal is detected.

Symptoms

• A16 alarm code shown on the MULTIFRESH NEXT control panel
• Defrost cycle may not terminate correctly or may run excessively long
• Ice accumulation on the evaporator if defrost is not completing properly
• RV5 temperature reading absent, erratic, or showing an out-of-range value on the display
• Possible water overflow near the evaporator drain if defrost overruns

Common causes

• Defrost end probe RV5 (NTC-type) faulty, open-circuit, or reading outside the expected range
• RV5 probe physically damaged by excessive ice formation on the evaporator encasing or stressing the probe
• PU power board analogue input for RV5 faulty
• Precarious or corroded connection of RV5 probe wires to M5 terminal block poles 3 and 4
• Oxide build-up on M5 terminal block poles 3 and 4

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Diagnostic steps

1. Inspect the evaporator and RV5 probe for ice damage

   Before touching any electrical connections, inspect the evaporator compartment for excessive ice formation. If the probe is encased in ice, perform a manual defrost cycle first, then inspect RV5 for mechanical damage caused by ice pressure.

2. Inspect and clean M5 terminal block poles 3 and 4

   Access the M5 terminal block and examine poles 3 and 4 where RV5 connects. Clean any oxide from the terminals, retighten the screw clamps, and confirm the probe wires are fully inserted and secure.

3. Measure RV5 NTC resistance

   Disconnect RV5 from M5 poles 3 and 4 and measure resistance at a known ambient temperature, comparing the result against the NTC curve in the MULTIFRESH NEXT service manual. An open circuit or far out-of-range reading confirms probe failure.

4. Replace RV5 probe if faulty

   Replace the defrost end probe with the correct Irinox-specified NTC sensor, positioning it on the evaporator per the service manual guidance and securing it so future ice formation cannot exert mechanical stress on the probe body.

5. Reconnect to M5 and verify alarm clearance

   Reconnect the replacement probe wires to M5 poles 3 and 4, restore power, and confirm A16 clears. Run through a defrost cycle and verify the controller correctly terminates defrost based on RV5 readings.

6. Assess PU power board analogue input if alarm persists

   If a verified good probe and clean terminals do not resolve A16, document probe measurements and escalate to board-level diagnosis of the PU power board analogue input for RV5.

When to call a professional

Escalate to an Irinox-authorised technician if A16 persists after probe replacement and terminal cleaning, or if significant ice build-up on the evaporator suggests a deeper refrigeration or drain system fault. PU power board replacement and refrigeration-system diagnosis must be performed by a qualified refrigeration engineer or Irinox service technician.