Electrical Service; Air Cooled Condensers - Model Drcu; Fan Speed Control; Charging - DA Data Cool Series Installation, Operation And Maintanance Manual

4.3

Electrical Service

Refer to Sections 3.1 to 3.5 for information regarding line voltage and control voltage wiring details.
4.4 Air Cooled Condensing Unit - Model DRCU

4.4.1 Fan Speed Control

Standard outdoor air cooled condensing units have a fan speed controller on the first fan. On single-fan
condensing unit this is the only means of control. A variable speed controller modulates the motor
speed based on system head pressure. The fan speed controller will normally not require field adjustment.

5.0 CHARGING

5.1

Voltage Phase Check

5.1.1 Evaporator

Prior to charging, the correct voltage phasing should be checked on the indoor evaporator. Check
blower direction on the evaporator by momentarily energizing the fan motor. Reverse any two of the
three line voltage wires at the line voltage field connection point to change the blower rotation.
Although the scroll compressor is phase dependent, units shipped from the factory are run tested,
ensuring the compressor rotation is consistent with the evaporator fan motor. However, a field change-
out the compressor may require checking proper phase. An out-of-phase compressor will draw relatively
low amps and both suction and discharge pressures will remain nearly equal.

5.1.2 Secondary Heat Exchanger

The secondary heat exchanger may be ordered as three phase but the individual fan motors are
single phase and will only run in one direction.
5.2

Air Cooled Systems

Before starting a compressor, the crankcase heater should be energized for a minimum of
12 hours to reduce the possibility of liquid slugging on start-up. Failure to energize the
crankcase heater could result in compressor damage.

5.2.1 Split Indoor Air Cooled Systems Charging

After the field refrigerant piping is properly completed, connect the refrigerant drum to the low side and
charge with vapor. Charge with approximately three lbs. per nominal ton.
For example, a model DACU 0334-AO is a nominal 3 ton unit. Charge with about 9 lbs. of refrigerant to
begin. It is likely that more refrigerant will be required to complete the charging procedure. Make sure
all hoses are properly purged.
Before starting a compressor, the crankcase heater should be energized for a minimum of
12 hours to reduce the possibility of liquid slugging on start-up. Failure to energize the
crankcase heater could result in compressor damage.
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