Pre-Start-Up; Start-Up; Service - Carrier COBRA 48/50HJ004-014 Installation And Service

PRE-START-UP

Failure to observe the following warnings could result in
serious personal injury.
1. Follow recognized safety practices and wear protec-
tive goggles and gloves when checking or servicing
refrigerant system.
2. Do not operate compressor or provide any electric
power to unit unless compressor terminal cover is in
place and secured.
3. Do not remove compressor terminal cover until
all electrical sources are disconnected and tagged
accordingly.
4. Relieve all pressure from system before touching
or disturbing any connections inside compressor ter-
minal box. If refrigerant leak is suspected around
compressor terminals, use accepted methods to recov-
er refrigerant.
5. Never attempt to repair or solder any components
while refrigerant system is under pressure.
6. Do not use torch to remove any component. System
contains oil and refrigerant under pressure. To remove
a component, wear protective goggles and gloves and
proceed as follows:
a. Shut off electrical power to unit and tag
disconnect.
b. Recover refrigerant to relieve all pressure from
system, using both high- and low-pressure
ports.
c. Cut component connection tubing with tubing
cutter, and remove component from unit.
d. Carefully unsweat remaining tubing stubs
when necessary. Oil can ignite when exposed to
torch flame.
Refer to 48/50HJ Installation Instructions for Pre-Start-Up
information for the rooftop unit section. Proceed as follows to
inspect and prepare the unit for initial start-up:
1. Remove filter access panel, blower access panel, and con-
trol panel access cover on the energy recovery section.
2. Read and follow instructions on all WARNING, CAU-
TION, and INFORMATION labels attached to (or
shipped with) unit.
3. Make the following inspections:
a. Inspect for shipping or handling damages such as
broken lines, loose parts, or disconnected wires.
b. Inspect for oil at all refrigerant tubing connections
and on unit base. Detecting oil usually indicates a
refrigerant leak. Leak-test all refrigerant tubing
connections using an electronic leak detector,
halide torch, or liquid-soap solution.
c. Inspect all field and factory wiring connections Be
sure that connections are completed and tight.
d. Inspect upper (supply) and lower (exhaust) coils
for damage and refrigerant leaks. If fin damage is
noted, carefully straighten fins using a fin comb.
4. Tighten compressor holddown bolts to 5.5 to 6.5 ft-lbs of
torque.
5. Verify the following:
a. If installed, ensure optional supply and exhaust
blower wheel set screws are tight and wheels are
centered within the blower housing.
b. Make sure supply and exhaust air filters are in
place.
c. Make sure the condensate drain is of correct
dimensions and primed with water to ensure
proper drainage.
d. Reinstall all access panels.
e. Ensure all tools and miscellaneous parts have been
removed.
Refer to the 48/50HJ Installation Instructions for informa-
tion on Start-Up for the rooftop unit section.
Unit Preparation —
stalled in accordance with installation instructions and applica-
ble codes.
Supply and Exhaust Filters —
correctly installed on unit. Do not operate without filters in
place.
Outdoor-Air Inlet Screens —
must be in place before operating the unit.
Compressor Mounting —
spring-mounted. Ensure wooden shipping block has been
removed from under the compressor and holddown bolts are in
place.
Internal Wiring —
nections for proper locations. Ensure connections are tight.
Cooling —
Set Light Commercial Thermidistat mode selec-
tion to Cooling and fan mode to Auto. Ensure thermostat has
been adjusted to a setting below room temperature. Refer to
Table 2 for correct unit operation.
Heating —
Set Light Commercial Thermidistat mode se-
lection to Heating and fan mode to Auto. Ensure thermostat has
been adjusted to a setting below room temperature. Refer to
Table 2 for correct unit operation.
Operating Sequence —
Light Commercial Thermidistat Start-Up and Checkout on
page 33, and Table 2 for energy recovery section operating
sequence. See Fig. 17.
Refer to base unit installation instructions or 62AQ Installa-
tion Instruction for all service information.
Fuse Box (48HJ012,014 — 208/230-3-60 Units
Only) —
Certain 48HJ units contain a fuses for the power
supply. The fuse box is located in the compressor section in a
single point box. See Fig. 18. Replacement fuses are cartridge
type, non-renewable, time delay FRN type of the appropriate
size and voltage. Refer to existing fuse size and voltage for
replacement.
35

START-UP

Make sure the unit has been in-
Make sure filters are
Outdoor-air inlet screen(s)
Compressors are internally
Check all low and high voltage con-
Refer to Step 5 — Conduct

SERVICE