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Outdoor-Air Inlet Screens
Outdoor-air inlet screen must be in place before operating unit.
Compressor Mounting
Compressors are internally spring mounted. Do not loosen or re-
move compressor hold down bolts.
Internal Wiring
Check all electrical connections in unit control boxes. Tighten as
required.
Refrigerant Service Ports
Each unit system has two 1/4-in. SAE flare (with check valves)
service ports: one on the suction line, and one on the compressor
discharge line. Be sure that caps on the ports are tight.
Compressor Rotation
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution can result in premature wear and
damage to equipment.
Scroll compressors can only compress refrigerant if rotat-
ing in the right direction. Reverse rotation for extended
times can result in internal damage to the compressor.
Scroll compressors are sealed units and cannot be repaired
on site location.
On 3-phase units with scroll compressors, it is important to be
certain compressor is rotating in the proper direction. To deter-
mine whether or not compressor is rotating in the proper
direction:
1.
Connect service gauges to suction and discharge pressure
fittings.
2.
Energize the compressor.
3.
The suction pressure should drop and the discharge
pressure should rise, as is normal on any start-up.
If the suction pressure does not drop and the discharge pressure
does not rise to normal levels:
1.
Note that the evaporator fan is probably also rotating in
the wrong direction.
2.
Turn off power to the unit and install lockout tag.
3.
Reverse any two of the unit power leads.
4.
Re-energize to the compressor. Check pressures.
The suction and discharge pressure levels should now move to
their normal start-up levels.
NOTE: When the compressor is rotating in the wrong direction,
the unit will make an elevated level of noise and will not provide
cooling.
Cooling
Set space thermostat to OFF position. To start unit, turn on main
power supply. Set system selector switch at COOL position and
fan switch at AUTO. position. Adjust thermostat to a setting be-
low room temperature. Compressor starts on closure of contactor.
Check unit charge. Refer to Refrigerant Charge section on
page 17.
Reset thermostat at a position above room temperature. Com-
pressor will shut off. Evaporator fan will shut off after a 30-
second delay.
To shut off unit, set system selector switch at OFF position. Reset-
ting thermostat at a position above room temperature shuts unit off
temporarily until space temperature exceeds thermostat setting.
Main Burner
Main burners are factory set and should require no adjustment.
To check ignition of main burners and heating controls, move
thermostat setpoint above room temperature and verify that the
burners light and evaporator fan is energized. Check heating ef-
fect, then lower the thermostat setting below the room temperature
and verify that the burners and evaporator fan turn off.
When replacing unit orifices, order the necessary parts through
RCD. See the "High Altitude Gas Conversion Kit Gas Heat-
ing/Electric Cooling 3-15 Ton Small Rooftop Units Accessory LP
(Liquid Propane) Installation Instructions" for details.
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 lockout.
To reset the control, break the 24 v power to W1.
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 de-
lay is 45 seconds. The Integrated Gas Unit Controller (IGC) modi-
fies 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 is observed, the evaporator-fan on/off delay
has been modified.
If the limit switch trips at the start of the heating cycle during 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 seconds, the evap-
orator-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 occur. If the limit switch trips during this pe-
riod, 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 temperature will
temporarily shut unit off until space temperature falls below
thermostat setting.
Ventilation (Continuous Fan)
Set fan and system selector switches at ON and OFF positions, re-
spectively. Evaporator fan operates continuously to provide con-
stant 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.
68
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Table of Contents
Troubleshooting
