Delfield STD4432N, D4464N freEZeR Cabinets, Thermostat Location - Freezer, Operation, Delfield

Delfield

OPERATION

freEZeR Cabinets

The electronic temperature control constantly monitors box temperature as well as evaporator coil temperature to maintain consistent product temperatures.

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.

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 initialization defrost is complete. This initial defrost cycle may take up to 15 minutes to complete, at which time the freezing cycle will begin.

The control is located in the rear of the cabinet (See Figure 6.). Freezers are factory set at mid-range to maintain about -3ºF (-19ºC) 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. Never turn the knob more than 1 dial number and always allow 8 hours for temperature stabilization before making any additional adjustments.

Freezer cabinets with two evaporators have counter-rotating fans to ensure even airflow throughout the cabinet. The left evaporator has a CCW motor and a clear fan blade and the right evaporator has a CW motor and a black fan blade.

The evaporator fan(s) and condenser fan will cycle off and on with the compressor to conserve energy.

Freezer:

Whenever the freezer is plugged in, and the control has completed initializing including the initial defrost cycle. The temperature control will cycle the compressor and condenser fan motor and evaporator 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 4-hours since the last defrost cycle OR if evaporator coil temperature drops below -34ºF (-37ºC) (indicating excessive frost on the coil.)

When the control enters the defrost mode, it switches off the evaporator fan motor, compressor and condenser fan motor, and switches on the defrost heater to warm the evaporator coil. Thereby melting 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.

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.

Figure 6. Thermostat Location - Freezer

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