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3. Coolers
Air Defrost Sequence of Operation
for Coolers
Air defrost units are preprogrammed for three defrost periods
daily. These periods are not reprogrammable. After 71/2
hours, the temperature control will turn the compressor off.
When the coil temperature reaches 38°F, the control will
terminate the defrost cycle.
Room Thermostat Settings:
• Approximate dial settings of control
0 = Unit off (not an electrical disconnect)
1 = 52°F (11°C)
2 = 49°F (9°C)
3 = 45°F (7°C)
4 = 41°F (5°C)
5 = 38°F (3°C)
6 = 34°F (1°C)
Cooler units utilize an electronic temperature control. The
temperature may be adjusted by setting the dial. This control
is preset to provide three off cycle defrosts daily. Defrosts are
temperature terminated and can not be reprogrammed. The
temperature control is programmed for minimum on cycle of
one minute and minimum off cycle of four minutes.
Maintenance
The evaporator section of a system should be checked
at least once for proper defrosting because the amount and
pattern of frosting can vary greatly. The frost build-up is
dependent on the temperature of the room, the type of product
being stored, how often new product is brought into the room
and percentage of time the door to the room is open.
System Standard Maintenance Guidelines
After first year of operation and under normal usage,
maintenance should cover the following items at least once
every six months:
1. Check and Tighten
ALL electrical connections.
2. Check all wiring and insulators.
3. Check contactors for proper operation and for worn
contact points.
4. Check all fan motors. Tighten motor mount bolts/
nuts and tighten fan set screws.
5. Clean the condenser coil surface.
6. Check the operation of the control system. Make
certain all safety controls are operating properly.
7. Check that all defrost controls are functioning
properly.
8. Clean the evaporator coil surface.
9. Clean the drain pan and check the drain pan and
drain line for proper drainage.
All Cooler Models
Cooler Defrost Control
Note: If power is interrupted to the unit during the
refrigeration off-cycle (system at temperature setpoint,
compressor off), the thermostat will initiate an extra defrost
period approximately one hour after power is restored.