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II−PLACEMENT AND INSTALLATION
Make sure the unit is installed in accordance with the
installation instructions and all applicable codes. See
accessories section for conditions requiring use of the
optional roof mounting frame (LARMF18/36 or
LARMFH18/24).
III−STARTUP − OPERATION
Refer to startup directions and to the unit wiring diagram
when servicing. See unit nameplate for minimum 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 or TB2. Volt-
age must be within the range listed on the nameplate.
If not, consult the power company and have the volt-
age corrected 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
The thermostat specified for use on this unit has three cool-
ing outputs.
1− Remove coil covers before starting unit.
2− Initiate first and second stage cooling demands ac-
cording to instructions provided with thermostat.
3− First−stage thermostat demand will energize com-
pressor 1. Second−stage thermostat demand will en-
ergize compressor 2. Third−stage thermostat de-
mand will energize compressor 3 (and 4 on
4−compressor units only). On units with an econo-
mizer, when outdoor air is acceptable, a first−stage
demand will energize the economizer; a second−
stage demand will energize compressor 1.
4−
180S & H, 210S, 240S,−
Units contain three refrigerant circuits or systems.
Evaporator and condenser coil refrigerant circuit 1
makes up stage 1 cooling. Evaporator and condenser
coil refrigerant circuit 2 makes up stage 2 cooling.
Evaporator and condenser coil refrigerant circuit 3
makes up stage 3 cooling. See figure 16.
210H, 240H, 300S −
Units contain four refrigerant circuits or systems. Evap-
orator and condenser coil refrigerant circuit 1 makes
up stage 1 cooling. Evaporator and condenser refriger-
ant circuit 2 makes up stage 2 cooling. Evaporator and
condenser refrigerant circuit 3 and 4 makes up stage 3
cooling. See figure 17.
FIGURE 16
REFRIGERANT STAGES
THREE−COMPRESSOR UNITS
1
2
3
Circuit 1 = Stage 1
Circuit 2 = Stage 2
Circuit 3 = Stage 3
FIGURE 17
REFRIGERANT STAGES
FOUR−COMPRESSOR UNITS
1
2
3
Circuit 1 = Stage 1
Circuit 2 = Stage 2
Circuit 3 & 4 = Stage 3
4
