Unit installation

SCXF-SVX01K-EN 75
Start-Up
To start the unit, complete the following steps in order.
Review “Preliminary Refrigerant Charging,” p. 35 in if
applicable. Confirm all steps were completed.
Air Cooled Only
• Charging is more accurate at higher outdoor
temperatures. If outdoor temperature is < 80°F,
temporarily disable fan pressure control switches.
See unit wiring diagrams and disconnect the wires
between switches and terminal strip.
• Do not attempt to charge system with low ambient
dampers operating (if applicable). Disable these
dampers in “Open” position before proceeding.
Evaporator load should be at least 70°F return air, 350
CFM/ton.
Work on only one circuit at a time. See section “General
Data,” p. 11 for compressor sequencing.
Note: R-410A compressors have belly band crankcase
heaters that must be energized 24 hours before
starting compressor. Power to the unit will energize
the heaters. Heaters will be energized during the
off-cycle as long as the unit has power. Failure to
perform these pre-start instructions could result in
compressor damage.
1. Verify compressor crank case heaters have been on for
at least 24 hours.
2. Make sure all service valves are open.
3. Attach a thermocouple type temperature sensor on
liquid
line close to liquid line service valve.To ensure
an accurate reading, clean line where sensor is
attached. After securing sensor to line, insulate sensor
and line to isolate it from ambient air.
4. Attach service gauges to suction and discharge ports.
5. Check low side pressure. Low pressure cutout opens
below
, and closes above, values in Table 36, p. 56.If
the low side pressure is less than the open psig,
refrigerant
may need to be added to the suction line
before starting the compressor(s) to close the switch.
SLOWLY meter into the suction line only as much R-
410A as needed to close the low pressure cutout. Use
the VAPOR charging connection. If possible, plan to
use this entire refrigerant bottle on the same unit in
order to minimize fractionalization. Use an accurate
scale to measure and record amount of R-410A added.
6. Switch the field supplied unit disconnect “OFF”.
Open
the unit control box and plug in the reset relay for only
the circuit being started.
7. Turn 115 volt control circuit switch “ON”.
Close control
box and switch field supplied unit disconnect “ON”.
Unit power should be off no longer than 60 minutes to
prevent refrigerant migration to compressor sumps. If
power is off for longer than 60 minutes, allow time for
crankcase heaters to drive refrigerant from
compressor sumps before starting compressors.
8. Adjust setpoints at the HI.
Note: Suf
ficient cooling load must be visible to
refrigerant circuit controls for mechanical
refrigeration to operate. If necessary, temporarily
reduce the discharge air setpoint to verify the
refrigeration cycle operation.
9. Check voltage at all compressor terminals to ensure it
is
within 10% of nameplate voltage.
10. Check voltage imbalance from these three voltage
readings
at each compressor. Maximum allowable
voltage imbalance, phase to phase is 2%.
11. Start the first step compressor only.
12. Check amp draw at compressor terminals. RLA and
LRA
are on the unit nameplate.
13. Measure amp draw at evaporator fan motor terminals.
FLA
data is on the motor nameplate.
WARNING
Live Electrical Components!
During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.
NOTICE:
Compressor Damage!
Never manually or automatically pump down system
below 7 psig.This will cause the compressor to operate
in a vacuum and result in compressor damage.
NOTICE:
Compressor Damage!
Keep crankcase heaters on whenever refrigerant is in
the system. If crankcase heaters have not been on with
refrigerant in the system, turn the crankcase heaters on
for a minimum of 24hours before starting compressors.
Failure to follow the above could result in compressor
failure or reduced compressor life.
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.