Freezer Models 403 & 407 Temperature Control Operation; Evaporator Fan Operation - Delfield 400 series Service And Installation Manual

Freezer Models 403 & 407 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
1-800-733-8829 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.

Evaporator Fan Operation

400 Refrigerator
400 Freezer
4000 Refrigerator
4000 Freezer
Cooling Cycle
Compressor On
Evap Fan Evap Fan Evap Fan
On Off
X
X
X
X
For customer service, call (800) 733-8829, (800) 773-8821, Fax (989) 773-3210, www.delfield.com
Compact Refrigerators and Freezers Service and Installation Manual
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.
Compressor Off Compressor Off
Evap Fan Evap Fan
On Off On
X
X
X
X
Defrost Cycle
Evap Fan
Off
X
X
X
X
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