Armstrong Air 4SCU 16LS Series, Installation And Maintenance Instructions Manual

Page: 14 / 32

506859-01 Issue 1236 Page 14 of 32
START-UP
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and field-installed wiring for loose
connections.
3. After evacuation is complete, open liquid line and
suction line service valves to release refrigerant charge
(contained in outdoor unit) into system.
4. Replace the stem caps and secure finger tight, then
tighten an additional 1/6 of a turn.
5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit
nameplate. If not, do not start equipment until the power
company has been consulted and the voltage condition
corrected.
6. Set thermostat for cooling demand, turn on power to
indoor blower, and close the outdoor unit disconnect
switch to start the unit.
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
Refrigerant Charging
This system is charged with R-410A refrigerant which
operates at much higher pressures than R-22. The liquid
line drier provided with the unit is approved for use with
R-410A. Do not replace it with one designed for use with
R-22. This unit is NOT approved for use with coils which
use capillary tubes as a refrigerant metering device.
R410A refrigerant cylinders are rose colored. Refrigerant
should be added through the suction valve in the liquid
state.
Certain R-410A cylinders are identified as being
equipped with a dip tube. These allow liquid refrigerant
to be drawn from the bottom of the cylinder without
inverting the cylinder. Do not turn this type of cylinder
upside down to draw refrigerant.
If the system is void of refrigerant, clean the system using
the procedure described below.
1. Use dry nitrogen to pressurized the system and check
for leaks. Repair leaks, if possible.
2. Evacuate the system to remove as much of the moisture
as possible.
3. Use dry nitrogen to break the vacuum.
4. Evacuate the system again.
5. Weigh the appropriate amount of R-410A refrigerant
(listed on unit nameplate) into the system.
6. Monitor the system to determine the amount of moisture
remaining in the oil. Use a test kit to verify that the
moisture content is within the kit’s dry color range. It
may be necessary to replace the filter drier several
times to achieve the required dryness level. If system
dryness is not verified, the compressor will fail in
the future.
The outdoor unit should be charged during warm weather.
However, applications arise in which charging must occur in
the colder months. The method of charging is determined
by the unit’s refrigerant metering device and the outdoor
ambient temperature.
Table 4
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
CAUTION
Mineral oils are not compatible with R-410A. If oil must
be added, it must be a polyolester oil.
IMPORTANT
Units are factory charged with the amount of R410A
refrigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with 15’
line set. For varying lengths of line set, refer to Table 4 for
refrigerant charge adjustment. A blank space is provided
on the unit rating plate to list the actual field charge.
Refrigerant Charge Adjustment
* If line length is greater than 15 ft. , add this amount.
If line length is less than 15 ft., remove this amount.
Liquid Line Set Diameter Oz. Per 5 ft. adjust from
15 ft. line set*
3/8 in. 3 oz. per 5 ft.