Kleenmaid PSA22 - Manual (Page 17)

The new high efficiency compressor runs faster and will have a higher pitch hum or
pulsating sound while operating.
The fan circulating air inside the freezer which keeps the temperatures throughout.
Water dropping on the defrost heater causing a sizzling, hissing or popping sound
during the defrost cycle.
The flow of refrigerant through the freezer cooling coils sounds like boiling water
or a gurgling noise.
Cracking or popping of cooling coils caused by expansion and contraction during
defrost and refrigeration following defrost.
Water dripping as it melts from the evaporator and flows to the drain pan during
the defrost cycle.
Icemaker (on some models)
The icemaker water valve will buzz when the icemaker fills with water. If the power
switch is in the I position it will buzz even if it has not yet been hooked up to water.
Keeping the power switch in the I position before it is hooked up to water can
damage the icemaker. To prevent this, set the power switch to the O position.
This will stop the buzzing.
The sound of cubes dropping into the bin and water running in pipes as
icemaker refills.
These sounds are normal
and are due mostly to highly
efficient operation.
17
Normal operating sounds.