START UP AND MAKE ADJUSTMENTS
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 compres-
sor 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, outdoor fan, and indoor blower
motors start. Observe that compressor and outdoor fan shut
down when control setting is satisfied and that indoor blower
shuts down after fan time delay expires.
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).
CHECKING HEATING 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 HEAT position and FAN switch in
AUTO position. Set cooling control above room temperature.
Observe that compressor, outdoor fan, and indoor blower
motors start. Observe that compressor and outdoor fan shut
down when control setting is satisfied and that indoor blower
shuts down after fan time delay expires.
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).
4. If system is equipped with supplemental or emergency heat
(resistance heaters), observe that when thermostat is placed in
EMERGENCY HEAT mode and temperature control is set
above room temperature that heaters and indoor blower come
on. Observe that heaters shut off when control setting is
satisfied and that the indoor blower shuts off after fan time
delay expires.
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
compressor access panel. The chart includes the required suction
line temperature at given suction line pressures and outdoor
ambient temperatures (See Table 13A-H and Fig. 30).
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.
NOTE:
Allow system to operate in the cooling mode for a
minimum of 10 minutes before checking or adjusting refrigerant
charge.
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. Failure to
adjust charge properly or correct the abnormal conditions will
cause damage to the unit.
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. Indoor coil 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 Charts” compare outdoor-air tem-
perature (°F db) with the Indoor coil air inlet temperature (°F
wb) to determine desired system operating superheat tempera-
ture. See Table 13A–H and Fig. 30.
6. Using ’’Required Suction-Tube Temperature (F)’’ table, com-
pare desired superheat temperature with suction (low-side)
operating pressure (psig) to determine proper suction-tube
temperature. See Fig. 30.
Fig. 25—Fan Blade Clearance
C95027
1/2 IN. MAX
FR OM FAN DECK
MOTOR SHAFT
MOTOR
20
