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C-Cooling Start up
Operation
1- Initiate first and second stage cooling demands ac
cording to instructions provided with thermostat.
2- KGB024/090 No Economizer Installed in Unit -A
first-stage cooling demand (Y1) will energize com
pressor 1 and the condenser fan. An increased cool
ing demand (Y2) will not change operation.
Units Equipped With Economizer -
When outdoor air is acceptable, a first-stage cooling
demand (Y1) will energize the economizer. An in
creased cooling demand (Y2) will energize com
pressor 1 and the condenser fan. When outdoor air
is not acceptable unit will operate as though no
economizer is installed.
3- KGB074 No Economizer Installed in Unit -
A first-stage cooling demand (Y1) will energize com
pressor 1 on low speed and the condenser fan. An
increased cooling demand (Y2) will energize com
pressor 1 on high speed.
Units Equipped With Economizer -
When outdoor air is acceptable, a first-stage cooling
demand (Y1) will energize the economizer. An in
creased cooling demand (Y2) will energize com
pressor 1 on low speed and the condenser fan.
When outdoor air is not acceptable unit will operate
as though no economizer is installed.
4- Units contain one refrigerant circuit or stage.
5- Unit is charged with R-410A refrigerant. See unit rating
plate for correct amount of charge.
6- Refer to Cooling Operation and Adjustment section for
proper method to check refrigerant charge.
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se
quentially to ensure correct compressor and blower rota
tion and operation. Compressor and blower are wired in
phase at the factory.
1- Observe suction and discharge pressures and blower
rotation on unit start-up.
2- Suction pressure must drop, discharge pressure must
rise, and blower rotation must match rotation marking.
If pressure differential is not observed or blower rotation is
not correct:
3- Disconnect all remote electrical power supplies.
4- Reverse any two field-installed wires connected to the
line side of K1 contactor. Do not reverse wires at blower
contactor.
5- Make sure the connections are tight.
Discharge and suction pressures should operate at their
normal start‐up ranges.
D-Safety or Emergency Shutdown
Turn off power to unit. Close manual and main gas valves.
IV-CHARGING
A-Refrigerant Charge and Check - All-Aluminum Coil
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, re
claim 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:
IMPORTANT - Charge unit in standard cooling mode
high compressor stage only.
1- Make sure outdoor coil is clean. Attach gauge manifolds
and operate unit at full CFM in cooling mode with econo
mizer disabled until system stabilizes (approximately five
minutes). Make sure all outdoor air dampers are closed.
2- Compare the normal operating pressures (see table 7
through 14) to the pressures obtained from the gauges.
Check unit components if there are significant differ
ences.
3- Measure the outdoor ambient temperature and the
suction pressure. Refer to the appropriate circuit
charging curve to determine a target liquid tempera
ture.
Note - Pressures are listed for sea level applications.
4- Use the same thermometer to accurately measure the
liquid temperature (in the outdoor section).
D If measured liquid temperature is higher than the
target liquid temperature, add refrigerant to the
system.
D If measured liquid temperature is lower than the
target liquid temperature, recover some refrigerant
from the system.
5- Add or remove charge in increments. Allow the system
to stabilize each time refrigerant is added or removed.
6- Continue the process until measured liquid tempera
ture agrees with the target liquid temperature. Do not
go below the target liquid temperature when adjusting
charge. Note that suction pressure can change as
charge is adjusted.
7- Example KG/KC 090: At 95°F outdoor ambient and a
measured suction pressure of 130psig, the target liq
uid temperature is 99°F. For a measured liquid tem
perature of 106°F, add charge in increments until
measured liquid temperature agrees with the target
liquid temperature.
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