Thesuctionanddischargepressurelevelsshouldnowmove
totheirnormalstart-uplevels.
NOTE:Whenthecompressorisrotatinginthewrongdirec-
tion,theunitwillmakeanelevatedlevelofnoiseandwillnot
providecooling.
Evaporator Fan -- Fan belt and variable pitch pulleys
am factoly-installed. See Tables 5-30 for fan performance cktta.
Be sum that fans rotate in the proper direction. See Table 31 for
air quantity limits. See Table 32 for evaporator fan motor
specifications. See Table 33 for fan rpm at various motor
pulley settings. To alter fan performance, see Evaporator Fan
Performance Adjustment section on page 39.
Cooling -- Set space thermostat to OFF position. To staff
unit, turn on main power supply. Set system selector switch at
COOL position and fan switch at AUTO. position. Adjust ther-
mostat to a setting below room temperature. Compressor starts
on closure of contactor
Check unit charge. Refer to Refrigerant Chmge section on
page 40.
Reset thermostat at a position above room temperature.
Compressor will shut off. Evaporator fan will shut off after a
30-second delay.
TO SHUT OFF UNIT -- Set system selector switch at OFF
position. Resetting thermostat at a position above room tem-
perature shuts unit off temporarily until space temperature ex-
ceeds thermostat setting. Units me equipped with Cycle-
LOC TM protection device. Unit shuts down on any safety trip,
and indicator light on thermostat comes on. Check reason for
all safety trips.
Compressor restart is accomplished by manu_d reset at the
thermostat by turning the selector switch to OFF and then to
ON position.
Main Burners -- Main burners ale factory set and should
require no adjustment.
TO CHECK ignition of main burners and heating controls,
move thermostat set point above room temperature and verily
that the burners light and evaporator fan is energized. Check
heating effect, then lower the themlostat setting below the
room temperature and verify that the burners and evaporator
fan turn off.
Heating
1. Purge gas supply line of air by opening union ahead of
the gas valve. If gas odor is detected, tighten union and
wait 5 minutes before proceeding.
2. Turn on electrical supply and manual gas valve.
3. Set system switch selector at HEAT position and fan
switch at AUTO. or ON position. Set heating temperature
lever above room temperature.
4. The induced-draft motor will start.
5. After a call for heating, the main burners should light
within 5 seconds. If the burner does not light, then there is
a 22-second delay before another 5-second try. If the
burner still does not light, the time delay is repeated. If the
burner does not light within 15 minutes, there is a lock-
out. To reset the control, break the 24 v power to WI.
6. The evaporator-fan motor will turn on 45 seconds after
burner ignition.
7. The evaporator-fan motor will turn off in 45 seconds after
the thermostat temperature is satisfied.
8. Adjust airflow to obtain a temperature rise within the
range specified on the unit nameplate.
NOTE: The default value for the evaporator-fan motor on/off
delay is 45 seconds. The Integrated Gas Unit Controller (IGC)
modifies this value when abnormal limit switch cycles occur
Based upon unit operating conditions, the on delay can be
reduced to 0 seconds and the off delay can be extended to
180 seconds. When one flash of the LED (light-emitting diode)
is observed, the evaporator-fan on/off delay has been modified.
If the limit switch trips at the stmt of the heating cycle dur-
ing the evaporator on delay, the time period of the on delay for
the next cycle will be 5 seconds less than the time at which the
switch tripped. (Example: If the limit switch trips at 30 sec-
onds, the evaporator-fan on delay for the next cycle will occur
at 25 seconds.) To prevent short-cycling, a 5-second reduction
will only occur if a minimum of 10 minutes has elapsed since
the last call for heating.
The evaporator-fan off delay can also be modified. Once the
call for heating has ended, there is a 10-minute period during
which the modification can occm: If the limit switch trips dur-
ing this period, the evaporator-fan off delay will increase by
15 seconds. A maximum of 9 trips can occur, extending the
evaporator-fan off delay to 180 seconds.
To restore the original default value, reset the power to the
unit.
TO SHUT OFF UNIT-- Set system selector switch at off
position. Resetting heating selector lever below room tempera-
ture will temporarily shut unit off until space temperature ftdls
below thermostat setting.
Safety Relief -- A soil-solder joint at the suction service
Schmder port provides pressure relief under abnormal tempera-
ture and pressure conditions.
Ventilation (Continuous Fan)- Set fan and system
selector switches at ON and OFF positions, respectively.
Evaporator fan operates continuously to provide constant air
circulation. When the evaporator-fan selector switch is turned
to the OFF position, there is a 30-second delay before the fan
turns off.
Operating Sequence
COOLING. UNITS WITHOUT ECONOMIZER -- When
thermostat calls for cooling, temfinals G and YI are energized.
The indoor-fan contactor (IFC) and compressor contactor
(CA.I) are energized and indoor-fan motol: compressor, and
outdoor fan staris. The outdoor-fan motor runs continuously
while unit is cooling.
When the thermostat is satisfied, YI and G deenergize. The
compressor stops immediately and the indoor fan will continue
to operate for 30 to 45 seconds.
HEATING, UNITS WITHOUT ECONOMIZER -- When the
thermostat calls for heating, termimfl WI is energized. To pre-
vent thermostat short-cycling, the unit is locked into the
Heating mode for at least 1 minute when WI is energized. The
induced-draft motor is energized and the burner ignition
sequence begins. The indoor (evaporator) fan motor (IFM) is
energized 45 seconds after a flame is ignited. On units
equipped for two stages of heat, when additional heat is need-
ed, W2 (if equipped) is energized and the high-fire solenoid on
the m_fin gas valve (MGV) is energized. When the thermostat
is satisfied and WI is deenergized, the IFM stops after a
45-second time-off delay.
COOLING. UNITS WITH ECONOMISER IV -- When free
cooling is not available, the compressors will be controlled by
the zone thermostat. When free cooling is av_filable, the
outdoor-air damper is modulated by the EconoMiSer IV con-
trol to provide a 50 to 55 F mixed-air temperature into the zone.
As the mixed-air temperature fluctuates above 55 or below
50 K the dampers will be modulated (open or close) to bring
the mixed-air temperature back within control.
If the load is high trod Y2 is energized, then the first stage of
mechanical cooling will be used to supplement the free cooling
provided by the economizel: If mechanic_fl cooling is utilized
with free cooling, the outdoor-air damper will maintain its
current position at the time the compressor is st_uted. If the
21
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