6
Three Phase Compressor Rotation
Use care when handling scroll compressors. Dome temperatures
could be hot.
CAUTION
Three phase scrolls are power phase dependent and can com-
press in more than one direction.
Verify proper rotation for three phase compressors by ensuring
the suction pressure drops and discharge pressure rises when
the compressor is energized. NOTE: When operated in reverse, a
three phase scroll compressors is noisier and its current draw
substantially reduced compared to marked values.
To correct, disconnect power and switch any two leads at the unit
contactor and re-observe.
High Voltage Connections
Route power supply and ground wires through the high voltage
port and terminate in accordance with the wiring diagram pro-
vided inside the control panel cover.
Low Voltage Connections
Condensing unit control wiring requires a two-conductor low volt-
age circuit from the room thermostat. The wiring should be no
smaller than 18 AWG and the field connection for this circuit
must be made in the unit control box using solderless connectors
(i.e. wire nuts). See the following diagram for a typical low volt-
age hook-up.
SINGLE STATE LOW VOLTAGE HOOK-UP
YELLOW
BLACK
WHITE
BLUE
BLUE
THERMOSTAT CHT18-60
CONDENSING
UNIT
CKL090/120
Y1
W1
R
G
AIR
HANDLER
AH090/120
RED
NOTES:
1). THERMOSTAT TO AIR HANDLER CABLE
MUST HAVE A MINIMUM OF (4) CONDUCTORS
2). AIR HANDLER TO CONDENSING UNIT CABLE
MUST HAVE A MINIMUM OF (2) CONDUCTORS
WIRE NUT
GREEN
System Start Up
Never operate the compressor with the suction valve closed to
test the compressor’s pumping efficiency. In some cases, this can
result in serious compressor damage and loss of warranty cover-
age.
For the 7-1/2 ton unit starting charge should be 15 lbs. of R-410A and
18 lbs. for the 10 ton unit. The length of line set, indoor unit
airflow, condensing unit location and number of tubing fittings
will have an impact on final unit charge amount. Turn the electri-
cal power on, and let the system run. Wait for the refrigerant
pressures to stabilize.
Charge Verification
CAUTION
NOTICE
Violation of EPA regulations may result in fines or other penalties.
Operating the compressor with the suction valve closed will void
the warranty and cause serious compressor damage.
CAUTION
Final Charge Adjustment
The outdoor temperature must be 60°F or higher. Set the room
thermostat to COOL, fan switch to AUTO, and set the temperature
control well below room temperature.
After system has stabilized per startup instructions, check sub-
cooling and superheat as detailed in the following section.
Expansion Valve System
NOTE: EXPANSION VALVE BULB MUST BE IN PLACE ON SUCTION LINE
& INSULATED.
Expansion Valve Indoors
At stabilized cooling conditions and with an outdoor temperature
of 60°F or higher, the system should have from 9°F to 13°F
subcooling. For a proper subcooling reading, measure the refrig-
erant pressure and temperature at the outdoor unit’s liquid line
service valve. If you have less than 9°F subcooling, slowly adjust
the charge by adding refrigerant. If you have more than 13°F
subcooling, slowly adjust the charge by removing refrigerant.
While reaching the proper subcooling level, it is important to
know the discharge line temperature. This temperature should be
at least 80ºF over ambient or refrigerant could flood back to com-
pressor.
Troubleshooting
Qualified Installer/Servicer Only
When troubleshooting, the first step should always be to check
for clean coils, clean filter(s), and proper airflow. Indoor airflow
should be 375 to 425 CFM per ton of cooling based on the size of
the outdoor unit. The most common way of establishing indoor
airflow is heating temperature rise. Indoor airflow will then be
(Heating output of equipment) / (1.1 x temp. rise). In other cases,
measurement of external static pressure is helpful. For details,
see the Installation Instructions for your indoor unit.
