Compact Refrigerators and Freezers Service and Installation Manual
For customer service, call (888) 732-2446 Fax (800) 669-0619, www.mccallrefrigeration.com
6
Freezer Models MCCSTF27 & MCCF27 Temperature Control Operation
After the unit is connected to power it will automatically
begin operating. With the doors closed, the temperature of
the cabinet should reach 0°F (-18°C) on freezers in about
one hour. Continuous opening and closing of the doors will
hamper the unit’s ability to maintain optimum temperature.
The electronic temperature control constantly monitors box
temperature as well as evaporator coil temperature to maintain
consistent product temperatures. As an added energy-saving
feature, the electronic controller will switch the evaporator
fan motor on and off with the compressor and condenser fan
motor.
At initial start-up or anytime power is disconnected, then
reconnected to the unit, the control will delay all operations for
a short time (up to 10 minutes.) While in this delay period, the
control initializes the control parameters and confirms that the
temperature sensors and circuits are operational.
Service Alert: During normal operation the evaporator fan
may cycle and/or pulse independently of the compressor.
Consult the service manual or contact Technical Support at
1-888-732-2446 if you are unsure of the proper function.
IMPORTANT NOTE REGARDING FREEZERS:
After initializing, the control will immediately enter a DEFROST
mode. The compressor and condenser fan as well as the
evaporator fan will remain off until initial defrost is complete.
This initial defrost cycle may take up to 15 minutes to
complete, at which time the freezing cycle will begin.
Whenever the freezer is plugged in, and the control has
completed initializing including the initial defrost cycle (see
above), the electronic temperature control will cycle the
compressor, evaporator fan motor, and condenser fan motor
to maintain box temperature at the control setting.
Freezer Automatic Defrost
The control also monitors compressor total running time
and will enter a defrost cycle after total compressor running
time is greater than 5-hours since the last defrost cycle OR
if evaporator coil temperature drops below -34°F (indicating
excessive frost on the coil).
Freezer Manual Defrost
If a manual defrost is desired, simply unplug the unit for
several seconds, then plug unit back in. This will cause the
control to re-initialize and then enter a defrost cycle.
When the control enters the defrost mode, whether manual
or automatic, it switches off the evaporator fan motor,
compressor and condenser fan motor, and switches on the
defrost heater to warm the evaporator coil and melt all frost
accumulated during the previous refrigeration cycle. The
control will continue the defrost cycle for a MINIMUM of 8
minutes and a MAXIMUM of 30 minutes depending on the
amount of frost accumulated on the evaporator coil.
After the defrost cycle is complete, the control returns to a
normal refrigeration cycle, however the evaporator fan motor
will not switch on for 2 minutes AFTER the compressor and
condenser fan motor have begun operating.
Electronic Temperature Control Location & Adjustment
Never turn the knob more than 1 dial number and always
allow 8 hours for temperature stabilization before making
any additional adjustments.
The control is located in the
control box at the rear of the unit (see photo). It is factory set
at mid-range to maintain about -3°F (-18°C) box temperature.
To adjust for colder temperatures, turn the knob clockwise.
For warmer temperatures, turn the knob counter-clockwise.
Turn the knob fully counter-clockwise to turn the refrigeration
system off.
Freezer Models MCCF48 & MCCSTF48 Temperature Control Operation
After the unit is connected to power it will automatically begin
operating. With the doors closed, the temperature of the
cabinet should reach 0°F (-18°C) on freezers in about one
hour.
A thermostat located in the evaporator housing on interior rear
of the unit, controls the temperature in the box. The factory
setting for the control is “4” and maintains about -3°F (-18°C)
in the box. Set toward “1” for higher temperatures and toward
“7” for lower temperatures.
Continuous opening and closing of the doors will hamper the
unit’s ability to maintain optimum refrigeration temperature.
When the mechanical timer initiates a defrost cycle, power to
the condensing unit and evaporator fans is interrupted and
the defrost heater is energized. The defrost heater warms the
evaporator coil thereby melting all frost accumulated during
the previous refrigeration cycle. Once all frost is eliminated,
the temperature of the coil continues to rise until it reaches 27
minutes. The defrost control switches to refrigeration mode.
Defrost will initiate every six hours.
Turn the defrost timer screw ONLY in a clockwise
direction, turning the screw counter-clockwise
will break the cam motor.
Service Alert
During normal operation the evaporator fan may cycle
and/or pulse independently of the compressor. Consult
the service manual or contact Technical Support at
1-888-733-2446 if you are unsure of the proper function.
