3-PHASE
CONNECTIONS
TO DISCONNECT
PER NEC
GROUND
LEAD
SINGLE-PHASE I_-
CONNECTIONS 4-
TO DISCONNECT[ L-
PER NEC L_ .....
L ......
UNIT GROUND
4333
_ Z_ BLK-
Fig. 13--Line Power Connections
C00012
4. Evacuate refrigerant system and reclaim refrigerant if no
additional leaks are lound.
5. Charge unit with R-22 refrigerant, using a volumetric-
charging cylinder or accurate scale. R@,r to nnit rating plate
.fi)r reqtlired charge. Be stare to add extra refi'igerant to
compensate flw internal volume of field-installed filter drier.
Step 2--Start-Up Cooling Section and Make Adjustments
Complete the required procedures given in the Pre-Start- Up
section this page belore starting the unit. Do not jumper any
salL'ty devices whelk operating the unit.
Do not operate the compressor when the outdoor temperature
is below 40 ° F.
Do not rapid-cycle the compressor. Allow 5 minutes between
"on" cycles to prevent conapressor damage.
CHECKING COOLING CONTROL OPERATION
Start and check the unit lkw proper cooling control operation as
Rfllows:
I. Place room thermostat SYSTEM switch ilk OFF position.
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 ilkCOOL position and FAN switch ilk
AUTO position. Set cooling control below room temperature.
Observe thai compressor, condenser fan, and evaporator
blower motors start. Observe that cooling cycle shuts down
when control setting is satisfied.
3. When using an automatic changeover room thermostat, place
both SYSTEM and FAN switches ilk AUTO. positions.
Observe that unit operates in Cooling mode when temperature
control is set to "call lk)rcooling" (below room temperature).
Step a--Refrigerant Charge
Amount of refi'igerant charge is listed on unit nameplate (also l'eler
to Table 1). Relk_l: to Carrier Refi'igerant Service Techniques
Manual, Refi'igerant section.
Unit panels nmst be in place when unit is operating during
charging procedure.
NO CHARGE
Use standard evacuating techniques. After evacuating system,
weigh in the specified amount of refi'igerant. (Relk_rto Table 1.)
LOW CHARGE COOLING
Use Cooling Charging Charts, Fig. 17 20. Vary refi'igerant until
the conditions of the appropriate chart are met. Note that charging
charts are different from the type normally used. Charts are based
10
<b
@
THERMOSTAT
AND SUBBASE
L_RED--4
_YEL---_
UNIT CONTROL BOX
Fig. 14--Control Connections
C00013
on charging the units to the correct superheat lot the various
operating conditions. Accurate pressure gauge and temperature
sensing device are required.
To measure suction pressure, perl_wm the flfllowing:
1. Connect the pressure gauge to the service port on the suction
line.
2. Mount the temperature sensing device on the suction line and
insulate it so that outdoor ambient temperature does not al]bct
the reading. Indoor-air cfin nmst be within the normal oper-
ating range of the unit.
TO USE COOLING CHARGING CHARTS
1. Take the outdoor ambient temperature and read the suction
pressure gauge.
2. RelL'r to appropriate chart to determine what the suction
tenq)erature should be.
3. If suction temperature is high, add refrigerant. If suction
temperature is low, carefully recover some of the charge.
4. Recheck the suction pressure as charge is adjusted.
EXAMPLE: (Fig. 17)
Outdoor Temperature ................. 85° F
Suction Pressure ................. 80 psig
Suction Temperature should be ........70 ° F
(Suction Temperature may vary +5°F.)
If Chargemaster® charging device is used, temperature and
pressure readings must be accomplished using the charging chart.
Step 4--Indoor Airflow and Airflow Adjustments
For cooling operation, the recommended airflow is 350 to 450
cfm ])el"each 12,000 Btnh o["rated cooling capacily.
Table 4 shows dry coil air delivery lot horizontal discharge units.
Tables 5-7 show pressure drops.
NOTE: Be sure that all supply- and return-air grilles are open,
free fi'om obstructions, and a_[justed properly.
Disconnect electrical power to the unit belk)re changing
blower speed. Elech'ical shock can cause injury or death.
Airflow can be changed by changing the lead connections of the
blower motor.
Units 50ZP036, 048, and 060 blower motors are factory wired lbr
low speed operation. Units 50ZP042 are lhctory wired flw medium
speed operation.
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