Page 35
IV-STARTUP - OPERATION
Refer to startup directions and refer closely to the unit wir-
ing diagram when servicing. See unit nameplate for mini-
mum circuit ampacity and maximum fuse size.
A-Preliminary and Seasonal Checks
1- Make sure the unit is installed in accordance with the
installation instructions and applicable codes.
2- Inspect all electrical wiring, both field and factory installed
for loose connections. Tighten as required. Refer to unit
diagram located on inside of unit control box cover.
3- Check to ensure that refrigerant lines are in good
condition and do not rub against the cabinet or other
refrigerant lines.
4- Check voltage at the disconnect switch. Voltage must
be within the range listed on the nameplate. If not,
consult the power company and have the voltage cor-
rected before starting the unit.
5- Recheck voltage and amp draw with unit running. If
voltage is not within range listed on unit nameplate,
stop unit and consult power company. Refer to unit
nameplate for maximum rated load amps.
6- Inspect and adjust blower belt (see section on Blower
Compartment - Blower Belt Adjustment).
B-Cooling Startup LGA/LCA
NOTE-Crankcase heaters must be energized 24 hours be-
fore attempting to start compressor. Set thermostat so that
there is no demand to prevent compressor from cycling.
Apply power to unit.
1- Initiate cooling demand according to instructions pro-
vided with thermostat.
2- Thermostat demand will energize compressor. On
units with an economizer, when outdoor air is accept-
able, a first-stage demand will energize the economiz-
er; a second-stage demand will energize compressor
1.
3- The unit is charged with HCFC-22 refrigerant. See unit
rating plate for correct amount of charge.
4- Refer to Cooling Operation and Adjustment section for
proper method to check refrigerant charge.
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se-
quentiallyto ensure correct compressor and blower rota-
tion and operation. Compressor and blower are wired in
phase at the factory. Power wires are color-coded as fol-
lows: line 1-red, line 2-yellow, line 3-blue.
1- Observe suction and discharge pressures and blower
rotation on unit start-up.
2- Suction pressure must drop, discharge pressure must
rise, and blower rotation must match rotation marking.
If pressure differential is not observed or blower rotation is
not correct:
3- Disconnect all remote electrical power supplies.
4- Reverse any two field-installed wires connected to the
line side of S48 disconnect or TB2 terminal strip. Do
not reverse wires at blower contactor.
5- Make sure the connections are tight.
Discharge and suction pressures should operate at their
normal start-up ranges.
To Next Page
Loading...
Need help?
General
