NEFF Microwave Oven Instruction Manual page 12

Cooking
compartment
Cooling fan
12
The appliance is equipped with a cooling fan. The fan
may run on even if the oven has been switched off.
Notes
The cooking compartment remains cold during
microwave operation. The cooling fan will still switch
on. The fan may run on even when microwave
operation has ended.
Condensation may appear on the door panel, interior
walls and floor. This is normal and does not affect
microwave operation. Wipe away the condensation
after cooking.