Operating instructions
AUXILIARY LIMIT SWITCH (ROLLOUT)
The function of the switch is to close the main gas valve in the
event of flame rollout. The switch is located above the main
burners. When the temperature at the auxiliary switch reaches the
maximum allowable temperature, the R control circuit trips,
closing the gas valve and stopping gas flow to the burners. The
indoor (evaporator) fan motor (IFM) and induced draft motor
continue to run until switch is reset. The IGC LED will display
FAULT CODE 7.
Step 3—START-UP COOLING AND MAKE ADJUST-
MENTS
Complete the required procedures given in the Pre-Start-Up
section before starting the unit.
Do not jumper any safety devices when operating the unit.
Do not operate the compressor 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 CONTROL OPERATION
Start and check the unit for proper cooling control operation 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 when FAN switch is placed in
AUTO. position.
2. Place SYSTEM switch in COOL position and FAN switch in
AUTO. position. Set cooling control below room temperature.
Observe that compressor, condenser fan, and evaporator
blower motors start. Observe that cooling cycle shuts down
when control setting is satisfied. The evaporator fan will
continue to run for 30 sec.
3. When using an auto-changeover room thermostat, place both
SYSTEM and FAN switches in AUTO. positions. Observe
that unit operates in Heating mode when temperature control
is set to ‘‘call for heating’’ (above room temperature) and
operates in Cooling mode when temperature control is set to
‘‘call for cooling’’ (below room temperature).
IMPORTANT: Three-phase, scroll compressor units
(48GS048 and 48GX030-060) are direction-oriented.
These units must be checked to ensure proper compressor
3-phase power lead orientation. If not corrected within 5
minutes, the internal protector shuts off the compressor.
The 3-phase power leads to the unit must be reversed to
correct rotation. When turning backwards, scroll compres-
sors emit elevated noise levels, and the difference between
compressor suction and discharge pressures may be dra-
matically lower than normal.
CHECKING AND ADJUSTING REFRIGERANT CHARGE
The refrigerant system is fully charged with R-22 refrigerant,
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.
A superheat charging chart is attached to the outside of the service
access panel. The chart includes the required suction line tempera-
ture at given suction line pressures and outdoor ambient tempera-
tures.
An accurate superheat, thermocouple- or thermistor-type ther-
mometer, a sling psychrometer, and a gauge manifold are required
when using the superheat charging method for evaluating 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 adjust-
ment 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 gauge hoses to low- and high-pressure service
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. Evaporator inlet-air temperature (°F wb).
c. Suction-tube temperature (°F) at low-side service fitting.
d. Suction (low-side) pressure (psig).
5. Using “Cooling Charging Charts,” compare outdoor-air tem-
perature (°F db) with the suction line pressure (psig) to
determine desired system operating suction line temperature
(See Fig. 18–30).
Table 7—Air Delivery (Cfm) at Indicated Temperature Rise and Rated Heating Input
HEATING
INPUT
(BTUH)
TEMPERATURE RISE °F
20 25 30 35 40 45 50 55 60 65 70
40,000 1500 1200 1000 857 750 667 600 545 500 — —
60,000 2250 1800 1500 1286 1125 1000 900 818 750 692 —
90,000 — — 2250 1929 1688 1500 1350 1227 1125 1038 964
115,000 — — — 2464 2156 1917 1725 1568 1438 1327 1232
130,000 — — — 2786 2438 2167 1950 1773 1625 1500 —
NOTE: Dashed areas do not fall within the approved temperature rise range of the unit.
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