Nor-Lake LABORATORY REFRIGERATORS AND FREEZERS - Manual (Page 3)

3 08/07 Rev. A 123952
REFRIGERATORS
During the operation of a refrigerator, frost will periodically form on the coil surface. Each time the
compressor cycles "off", the evaporator fans will continue to run, which will keep the internal
temperature uniform and at the same time remove any frost build up on the coil. The water
produced will collect in the unit cooler drain pan and travel down the drain tube to the condensate
vaporizer.
FREEZERS
After shutting the door on freezer models, a short amount of time must be allowed before the door
can be reopened. This is due to the tight seal maintained between the door and the cabinet. Waiting
a few moments for the pressure to equalize permits the door to be opened easily.
A positive defrost is required to remove frost from the coil in freezer models. This is accomplished
by energizing heaters during the defrost cycle that are positioned on the coil surface. The
programmable controller is factory set to allow four defrosts per day.
As the preset defrost time is reached, the controller automatically terminates the refrigeration
process by turning off the condensing unit and unit cooler fan motors, and energizes the defrost
heaters. As the coil temperature increases, the frost begins to melt producing water that runs down
the coil to the unit cooler drain pan and exits through the drain tube to the vaporizer. After all the
frost has been removed and the coil temperature reaches approximately 50°F, the defrost is
terminated through the action of the defrost termination control located on the unit cooler, and the
refrigeration process resumes. In order to insure that any excess water remaining on the coil is not
sprayed into the cabinet interior, and all heat generated by the defrost is removed, the unit cooler
fans will not operate until the coil temperature reaches approximately 25°.
GENERAL MAINTENANCE
PERIODIC CLEANING
Beginning with the initial installation, the interior surfaces of the cabinet should be periodically
wiped down with a solution of warm water and baking soda. This solution will remove any odors
from spillage that has occurred. The exterior of the cabinet should also be cleaned frequently with a
commercial grade glass cleaner.
Monthly cleaning of the condenser will aid the heat transfer characteristics of the refrigeration
system and increase its efficiency. Dust, dirt, and lint will tend to accumulate on the fins of the
condensing unit. This obstruction will affect the flow of air through the condenser, thereby lowering
the efficiency of the system. A wire brush or a brush with stiff bristles can be used to loosen these
particles that are attached to the fins so that they may be removed with a vacuum cleaner. Failure
to keep the condenser coil clean and clear of obstructions could result in temperature loss
and damage to the compressor.
All moving parts have been permanently lubricated and will generally require no maintenance.