Unox AF39

What does Unox AF39 mean?

AF39 means the cooking chamber ceiling temperature is too high. The top temperature probe, which monitors overheating of the ceiling, has read a value above the allowed limit, so the oven raises this alarm to protect the chamber and components from excessive heat at the top of the cavity.

Symptoms

• AF39 shown on the control panel
• Oven stops or limits heating
• Top of the chamber running hotter than expected
• Alarm recurs at high set temperatures

Common causes

• Genuine overheating of the chamber ceiling
• Top temperature probe fault or out-of-range reading
• Cooling fan not activating to cool the structure
• Heating control fault driving the chamber too hot

Diagnostic steps

1. 01

   Let the oven cool

   Allow the cooking chamber to cool before investigating, then retry to see if the alarm clears.

2. 02

   Check the top probe

   Verify the top (ceiling) temperature probe is connected and reading correctly, as it monitors ceiling overheating.

3. 03

   Confirm cooling operation

   Check that the cooling fan activates as designed when the oven gets hot.

4. 04

   Investigate heating control

   If the chamber genuinely overheats, have the heating control and contactors checked for uncontrolled heating.

When to call a professional

AF39 signals an over-temperature condition at the chamber ceiling. Confirming the top probe and ruling out a heating-control fault requires accessing the oven internals and testing. If letting the oven cool does not clear a recurring AF39, have a qualified Unox technician investigate before further use.