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Cooling Start-Up
IMPORTANT-The crankcase heater must be energized
for 24 hours before attempting to start compressor. Set
thermostat so there is no demand to prevent
compressors from cycling. Apply power to unit.
A-Start-Up
1- Initiate full load cooling operation using the following
mobile service app menu path:
RTU MENU > SERVICE > COMPONENT TEST > COOLING
> COOL 4
2- Refer to Cooling Operation section for cooling
start-up.
3- Units have two refrigerant circuits. See figure 22.
4- Each refrigerant circuit is charged with R410A
refrigerant. See unit rating plate for correct
amount of charge.
5- Refer to Refrigerant Check and Charge section for
proper method to check refrigerant charge.
B-R410A Refrigerant
Units charged with R410A refrigerant operate at much
higher pressures than R22. The expansion valve and
liquid line drier provided with the unit are approved for use
with R410A. Do not replace them with components
designed for use with R22.
R410A refrigerant is stored in a pink cylinder.
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0-800 on the high side and a low
side of 30” vacuum to 250 psi with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psi of pressure with a 4000 psi burst rating.
IMPORTANT
Mineral oils are not compatible with R410A. If oil
must be added, it must be a polyol ester oil.
C-Refrigerant Charge and Check
WARNING-Do not exceed nameplate charge under
any condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge,
evacuate the system,
and
add
required nameplate charge.
NOTE - System charging is not recommended below
60°F (15°C). In temperatures below 60°F (15°C) ,
the
charge
must
be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
FIGURE 22
REFRIGERANT STAGES
TRADITIONAL FIN/TUBE COIL
1
2
(BOTH FANS ARE ENERGIZED
WITH A Y1 DEMAND)
CONDENSER COIL
STAGES 1 & 2
EVAPORATOR
COIL STAGE 1
EVAPORATOR
COIL STAGE 2
B4
B5
1-
Attach gauge manifolds to discharge and suction lines.
With the economizer disabled, operate the unit in
cooling mode at high speed
using the following mobile
service app menu path:
SERVICE > COMPONENT TEST > COOLING > COOL 4
2- Use a thermometer to accurately measure the
outdoor ambient temperature.
3- Apply the outdoor temperature to tables 4 through 11
to determine normal operating pressures.
Pressures are listed for sea level applications at
80
5
F dry bulb and 67
5
F wet bulb return air.
4- Compare the normal operating pressures to the
pressures obtained from the gauges. Minor
variations in these pressures may be expected due to
differences in installations. Significant differences
could mean that the system is not properly charged
or that a problem exists with some component in the
system.
Correct any system problems before
proceeding.
5- If discharge pressure is high, remove refrigerant from
the system. If discharge pressure is low, add
refrigerant to the system.
Add or remove charge in increments.
Allow the system to stabilize each time
refrigerant is added or removed.
6- Use the following subcooling method along with the
normal operating pressures to confirm readings.
