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II. HEATING SECTION START-UP AND ADJUSTMENTS
CAUTION: Complete the required procedures given
in Pre-Start-Up section on this page before starting unit.
Do not jumper any safety devices when operating the unit.
A. Checking Heating Control Operation
Start and check the unit for proper heating control operation
as follows:
1. Turn on unit electrical supply.
2. Set system switch selector at HEAT position and fan switch
at AUTO. position. Set heating temperature lever above
room temperature.
3. The evaporator fan will start immediately. The first stage
of thermostat energizes the first-stage electric heater el-
ements; second stage energizes second stage electric heater
elements, if installed.
4. Check for heating operation by verifying that unit sup-
ply outlets are functional. If electric heaters do not en-
ergize, reset limit switch (located on evaporator-fan scroll)
by depressing button located between terminals on the
switch.
5. The evaporator fan and heaters will turn off after ther-
mostat temperature is satisfied.
6. To shut off unit, set system switch selector at OFF po-
sition. Resetting thermostat at a position below room tem-
perature temporarily shuts unit off until space
temperature falls below thermostat setting.
B. Heating Sequence of Operation
For units without economizer, on a call for heating through
terminal W1, IFC and heater contactor no. 1 (HC1) are en-
ergized. On units equipped for 2 stages of heat, when addi-
tional heat is needed HC2 is energized through W2.
For units with economizer or accessory two-position damper,
on a call for heat through W1, the IFC energizes to start the
evaporator fan and the economizer damper blade opens to the
minimum position. If the accessory two-position damper is
used, the outdoor-air damper opens to the minimum position
whenever the evaporator fan runs. If unit is equipped with 2
stages of heat, when additional heat is needed a call is made
through W2.
As space temperature approaches the heating temperature
set point, heating stages cycle off. Economizer or accessory
two-position damper returns to fully closed position.
C. Safety Relief
A soft solder joint at the suction line fitting provides pres-
sure relief under abnormal temperature and pressure
conditions.
D. Ventilation (Continuous Fan)
Set fan and system switch selectors at ON and OFF posi-
tions, respectively. Evaporator fan operates continuously to
provide constant air circulation.
E. Limit Switches
The heating limit switches (LS) are normally closed. If the
leaving-air temperature exceeds the maximum allowable tem-
perature, one of the limit switches will open, breaking the
power circuit to the heater. This causes the heater to shut
down immediately. Check the air quantity to ensure there is
sufficient airflow.
If unit does not energize, reset the normally closed manual
limit switch (LSM). The LSM is located on the fan housing
and will only open in the event of a fan failure. The LSM re-
set button is located between terminals on the switch.
F. Airflow and Temperature Rise
The heating operation airflow must produce a temperature
rise that falls within the approved cfm range (300 to 500 cfm
per 12,000 Btuh cooling).
Refer to Indoor Airflow and Airflow Adjustments section on
page 20 to adjust heating airflow where required.
G. Safety Check of Limit Control
A manual reset limit control is located on the evaporator fan.
The control shuts off the unit in the event of fan failure.
III. COOLING SECTION START-UP AND ADJUSTMENTS
CAUTION: Complete the required procedures given
in the Pre-Start-Up section on page 17 before starting
the unit.
Do not jumper any safety devices when operating the
unit.
Do not operate the compressor when the outdoor tem-
perature is below 25 F (unless accessory low ambient
kit is installed).
Do not rapid-cycle the compressor. Allow 5 minutes be-
tween ''on'' cycles to prevent compressor damage.
A. Checking Cooling Control Operation
Start and check the unit for proper cooling control operation
as follows:
1. Place room thermostat SYSTEM switch in OFF posi-
tion. 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 tem-
perature. Observe that compressor, condenser fan mo-
tor, and evaporator-fan motor start. Observe that cool-
ing cycle shuts down when control setting is satisfied or
reset thermostat at a position above room temperature.
Compressor will shut off.
3. Check unit charge. See section B below.
4. To shut off unit, set system switch selector at OFF po-
sition. Resetting thermostat at a position above room tem-
perature shuts unit off temporarily until space
temperature exceeds thermostat setting. Units are
equipped with Cycle-LOC™ protection device. Unit shuts
down on any safety trip and remains off; an indicator
light on thermostat comes on. Check reason for safety
trip.
5. When using an auto-changeover room thermostat, place
both SYSTEM and FAN switches in AUTO. positions.
Observe that unit operates in Heating mode when tem-
perature control is set to ''call for heating'' (above room
temperature) and operates in Cooling mode when tem-
perature control is set to ''call for cooling'' (below room
temperature).
6. Compressor restart is accomplished by manual reset at
the thermostat by turning the selector switch to OFF
position and then to ON position.
B. Checking and Adjusting Refrigerant Charge
The refrigerant system is fully charged with R-22 refriger-
ant, 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. This unit uses charging charts to determine proper
charge. See Refrigerant Charge section on page 31 for fur-
ther details.
—18—
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