START-UP
Use the Start-Up Checklist supplied at the end of this book,
and proceed as follows:
Check for Refrigerant Leaks —
Locate and repair
refrigerant leaks and charge the unit as follows:
1. Using both high- and low-pressure ports, locate leaks and
reclaim remaining refrigerant to relieve system pressure.
2. Repair leak following accepted practices.
NOTE: Install a filter drier whenever the system has been
opened for repair.
3. Check system for leaks using an approved method.
4. Evacuate refrigerant system and reclaim refrigerant if no
additional leaks are found.
5. Charge unit with R-22 refrigerant, using a volumetric-
charging cylinder or accurate scale. Refer to unit rating
plate for required charge. Be sure to add extra refrigerant
to compensate for internal volume of filter drier.
Unit Start-Up Adjustments
Complete the required procedures given in the Pre-
Start-Up section page 17 before starting the unit.
Do not jumper any safety devices when operating the
unit.
Do not operate the unit in Cooling mode when the
outdoor temperature is below 40 F (unless accessory low-
ambient kit is installed).
Do not rapid-cycle the compressor. Allow 5 minutes
between ‘‘on’’ cycles to prevent compressor damage.
CHECKING COOLING AND HEATING CONTROL OP-
ERATION — Start and check the unit for proper control op-
eration as follows:
1. Place room thermostat SYSTEM switch in OFF position.
Observe that blower motor starts when FAN switch is placed
in ON position and shuts down within 30 seconds when
FAN switch is placed in AUTO. position.
2. Place SYSTEM switch in COOL position and FAN switch
in AUTO. position. Set control below room temperature.
Observe that compressor, outdoor fan, and indoor blower
motors start. Observe that cooling cycle shuts down when
control setting is satisfied.
3. Place system switch in HEAT position. Set control above
room temperature. Observe that heating cycle shuts down
when control setting is satisfied.
4. When using an automatic changeover room thermostat,
place both SYSTEM and FAN switches in AUTO. posi-
tions. Observe that unit operates in Cooling mode when
temperature control is set to ‘‘call for Cooling’’ (below
room temperature), and unit operates in Heating mode
when temperature control is set to ‘‘call for heating’’ (above
room temperature).
IMPORTANT: Scroll compressors in the 048 and
060 size units are direction-oriented. Three-phase
units must be checked to ensure proper compressor
3-phase power lead orientation. If not corrected within
5 minutes, the internal protector will shut off the
compressor. The 3-phase power leads to the unit must
be reversed to correct rotation. When turning back-
wards, scroll compressors emit elevated noise lev-
els, and the difference between compressor suction
and discharge pressures may be dramatically lower
than normal.
CHECKING AND ADJUSTING REFRIGERANT CHARGE
— The refrigerant system is fully charged with R-22 refrig-
erant, and is tested and factory sealed.
NOTE: Adjustment of the refrigerant charge is not required
unless the unit is suspected of not having the proper R-22
charge. The charging label and the tables shown refer to sys-
tem temperatures and pressures in Cooling mode only. If charge
level is suspect in Heating mode, reclaim all refrigerant and
charge to nameplate amount.
A superheat charging label is attached to the inside of the
compressor access door. The label includes a ‘‘Superheat Charg-
ing Table’’ and a ‘‘Required Suction-Tube Temperature (F)’’
chart.
An accurate superheat, thermocouple-, or thermistor-type
thermometer, a sling psychrometer, and a gage manifold are
required when using the superheat charging method for evalu-
ating the unit charge. Do not use mercury or small dial-type
thermometers because they are not adequate for this type of
measurement.
When evaluating the refrigerant charge, an indicated ad-
justment to the specified factory charge must always be
very minimal. If a substantial adjustment is indicated,
an abnormal condition exists somewhere in the cooling
system, such as insufficient airflow across either coil or
both coils.
Proceed as follows:
1. Remove caps from low- and high-pressure service
fittings.
2. Using hoses with valve core depressors, attach low- and
high-pressure gage hoses to low- and high-pressure serv-
ice fittings, respectively.
3. Start unit in Cooling mode and let unit run until system
pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient-air temperature (F db).
b. Indoor inlet-air temperature (F wb).
c. Suction-tube temperature (F) at low-side service
fitting.
d. Suction (low-side) pressure (psig).
5. Using Superheat Charging Tables 4A-4G, compare outdoor-
air temperature (F db) with indoor-air temperature (F wb)
to
determine
desired
system
operating
superheat
temperature.
6. Using Required Suction-Tube Temperature (F) Table 5,
compare desired superheat temperature with suction (low-
side) operating pressure (psig) to determine proper suction-
tube temperature.
7. Compare actual suction-tube temperature with proper
suction-tube temperature. Using a tolerance of ±3° F, add
refrigerant if actual temperature is more than 3° F higher
than proper suction-tube temperature, or remove refrig-
erant if actual temperature is more than 3° F lower than
required suction-tube temperature.
NOTE: If the problem causing the inaccurate readings is a
refrigerant leak, refer to Check for Refrigerant Leaks sec-
tion on this page.
18
