Miele KT 4353 SD ed Operating And Installation Manual page 28

Remember that the noise of the compressor and the coolant circulating in the
system is unavoidable.
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Humming noise made by the motor (compressor). This noise can
get louder for brief periods when the motor is switching on.
A gurgling noise can be heard when coolant is circulating
through the pipes.
Clicking sounds are made when the thermostat switches the
motor on and off.
On multi-zone and frost free appliances you can sometimes just
hear the movement of air circulating inside the appliance.
level, by raising or lowering the screw feet underneath the
appliance.
Move it away.
all removable items and refit them correctly.
Separate them.
Remove the clips.
Realign the appliance using a spirit
Check