Specifications

6
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
coverage.
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 fit-
tings will have an impact on final unit charge amount. Turn the
electrical power on, and let the system run. Wait for the refrig-
erant pressures to stabilize.
Charge Verification
REFRIGERANT UNDER PRESSURE!
• Do not overcharge system with refrigerant.
• Do not operate unit in a vacuum or at negative pres-
sure.
Failure to follow proper procedures may cause
property damage, personal injury or death.
WARNING
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 tem-
perature control well below room temperature.
After system has stabilized per startup instructions, check
subcooling 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 IN-
DOORS: 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, mea-
sure the refrigerant 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 re-
frigerant could flood back to compressor. If flooding (i.e. low
discharge line temperature) occurs, adjust valve stem on ex-
pansion valve inward (clockwise viewing end of expansion valve).
This will increase the super heat. After achieving the proper
subcooling and a sufficient discharge temperature, make small
adjustment to expansion valve stem to reach 8º to 10ºF of
super heat. Adjust the valve stem clockwise to increase the
superheat and adjust the valve stem counter clockwise to de-
crease the super heat. If the system is performing properly,
reinstall the service port caps and the valve bonnets. With the
valve opened, the valve bonnet is the primary seal against re-
frigerant leaks. Apply two drops of clean oil to the cap threads,
allowing the oil to run down to the inner cap seal surface. Close
caps finger-tight. Then tighten cap additional two to three hex
flats.
NOTE: Subsequent opening and replace of the cap will require
only 1/2 to 1 hex flat. See the table below for the torque required
for an effective seal on the valve bonnet (1/6 turn past finger
tight.
TUBING SIZE
TORQUE
(ft-lbs)
5/8 14
1 3/8 16
After closing the valve bonnet, perform a final refrigerant leak
test on the valves and sweat connections. Return the room
thermostat to the desired settings.
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 help-
ful. For details, see the Installation Instructions for your indoor
unit.