Carrier 50ZP024 Installation Instructions Manual page 10

START- - UP
Use the Start- -Up Checklist supplied at the end of this book, and
proceed as follows:
Step 1 — Check for Refrigerant Leaks
LOCATE AND REPAIR REFRIGERANT LEAKS AND
CHARGE THE UNIT AS FOLLOWS:
1. Using both high- - and low- -pressure ports, locate leaks and
reclaim remaining refrigerant to relieve system pressure.
2. Repair leak following accepted practices.
NOTE: Install a filter drier whenever the system has been opened
for repair.
3. Check system for leaks using an approved method.
4. Evacuate refrigerant system and reclaim refrigerant if no
additional leaks are found.
5. Charge unit with
volumetric- -charging cylinder or accurate scale. Refer to
unit rating plate for required charge. Be sure to add extra
refrigerant to compensate
field- -installed filter drier.
Step 2 — Start- -Up Cooling Section and Make
Adjustments
CHECKING COOLING CONTROL OPERATION — Start and
check the unit for proper cooling control operation as follows:
1. Place room thermostat SYSTEM switch in 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 in COOL position and FAN switch
in AUTO position. Set cooling control below room
temperature. Observe that 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 in AUTO.
positions. Observe that unit operates in Cooling mode when
temperature control is set to "call for cooling" (below room
temperature).
Step 3 — Refrigerant Charge
Amount of refrigerant charge is listed on unit nameplate (also refer
to Table 1). Refer to Carrier Refrigerant Service Techniques
Manual, Refrigerants section.
Unit panels must 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 refrigerant
(refer to Table 1).
LOW CHARGE COOLING — Use Cooling Charging Charts, Fig.
14- -19. Vary refrigerant until the conditions of the appropriate chart
are met. Note that charging charts are different from the type
normally used. Charts are based on charging the units to the correct
superheat for the various operating conditions. Accurate pressure
gage and temperature sensing device are required.
To measure suction pressure, perform the following:
R- -22 refrigerant, using
for internal volume of
1. Connect the pressure gage 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
affect the reading. Indoor- -air cfm must be within the
normal operating range of the unit.
TO USE COOLING CHARGING CHARTS
1. Take the outdoor ambient temperature and read the suction
pressure gage.
2. Refer to appropriate chart to determine what the suction
temperature 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. 14)
Outdoor Temperature .....................85_F (29_C)
a
Suction Pressure .......................80 psig
Suction Temperature should be .............70_F (21_C)
(Suction Temperature may vary ±5_ F. [2.8_C])
If Chargemasterr charging device is used, temperature and
pressure readings must be accomplished using the charging
chart.
Step 4 — Indoor Airflow and Airflow Adjust-
ments
NOTE: For cooling operation, the recommended airflow is 350
to 450 CFM for each 12,000 Btuh of rated cooling capacity.
Table 2 shows dry coil air delivery for horizontal discharge units.
Tables 3- -NO TAG show pressure drops.
NOTE: Be sure that all supply- - and return- -air grilles are open,
free from obstructions, and adjusted properly.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Disconnect electrical power to the unit and install lockout
tag before changing blower speed.
Airflow can be changed by changing the lead connections of the
blower motor.
Units 50ZP024,036,048, and 060 blower motors are factory wired
for low speed operation. Units 50ZP030 and 042 are factory wired
for medium speed operation.
FOR 208/230- -V — The motor leads are color- -coded as follows:
3- - SPEED
black = high speed
blue = medium speed
red = low speed
To change the speed of the blower motor (BM), remove the fan
motor speed leg lead from the indoor (evaporator) fan relay (IFR)
and replace with lead for desired blower motor speed. Insulate the
removed lead to avoid contact with chassis parts.
10
2- - SPEED
black = high speed
red = low speed