Carrier 50NQ - Manual (Page 7)

HIGH-VOLTAGE CONNECTIONS
The unit must have a separate electrical service with a field-
supplied, waterproof disconnect switch mounted at, or
within sight from the unit. Refer to the unit rating plate
(Fig. 4) for meiximum over-current device size and minimum
circuit amps (ampacity) for wire sizing.
The field-supplied disconnect switch box may be mounted
on the unit over the high-voltage inlet hole in the control
corner panel. See Figs. 2 and 3.
Proceed as follows to complete the high-voltage connections
to the unit:
1. Connect ground lead to chassis ground connection
when using separate ground wire.
2. Run high voltage leads into unit through inlet hole in
control box post, and to contactor through the hole in
the bottom of control box. The high voltage leads
should remain in conduit until entering control box and
a watertight termination should be made at bottom of
control box.
SPECIAL PROCEDURES FOR 208-V OPERATION
A WARNING
Make sure that the power supply to the unit is switched
OFF before making any wiring changes. Electrical
shock can cause personal injury or death.
For operation of 208 volts, disconnect the yellow
transformer-primary lead from the contactor. See the unit
wiring label. Remove the tape and cover from the termined
on the end of the blue tremsformer-primeiry lead. Save the
cover. Connect the blue lead to the contactor terminal from
which the yellow lead was disconnected.
Using the cover removed from the blue lead, insulate the
loose terminal on the yellow lead. Wrap the cover with elec­
trical tape so that the metal terminal cannot be shorted.
Indoor blower motor speed taps should be changed for 208V
operation on 208/230v rated units. Interchange motor lead
at blower motor. See “Start-up and Adjustments” section
(page 9) and unit wiring label.
CONTROL VOLTAGE CONNECTIONS
Locate the room thermostat on an inside wall in the space to
be conditioned where it will not be subjected to either a cool­
ing or heating source or direct exposure to sunlight. Mount
the thermostat 4 to 5 ft above the floor.
Use No. 18 AWG color-coded, insulated (35 C minimum)
wires to make the control voltage connections between the
thermostat and the unit. If the thermostat is located more
than 100 ft from the unit (as measured along the control
voltage wires), use No. 16 AWG color-coded, insulated (35 C
minimum) wires.
A grommeted control voltage inlet hole is located in the
panel adjacent to the control access panel. See Figs. 2 and 3.
Run the low-voltage leads from the thermostat, through the
inlet hole, and to the control voltage terminals. Connect the
thermostat leads to the terminals as shown in Fig. 10.
HEAT ANTICIPATOR SETTING
Factory thermostats have fixed heat anticipator settings.
No adjustment is required.
CIRCUIT BREAKER
Unit has manual reset circuit breaker which is located in the
low-voltage wiring box adjacent to low-voltage terminal
board. If unit fails to operate, first check breaker for tripped
position. If breaker is tripped, re-set and try to start unit. If
breaker continues to trip there is a problem in the low-
voltage electrical circuit (electrical short, ground, or trems-
former overload). Correct the condition and check for nor­
mal unit operation.
PREPARING UNIT FOR START-UP
A WARNING
Failure to observe the following warnings could result
in serious personal injury:
1. Follow recognized safety practices and wear protec­
tive goggles when checking or servicing refrigerant
system.
2. Do not operate compressor or provide any electric
power to unit unless compressor termined cover is in
place and secured.
3. Do not remove compressor terminal cover until edl
electrical sources have been disconnected.
4. Relieve all pressure from system before touching or
disturbing anything inside compressor termined box
if refrigerant leak is suspected eiround terminals.
5. Never attempt to repair soldered connection 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
proceed as follows:
a. Relieve all pressure from system.
b. Cut component connecting tubing with tubing
cutter and remove component from unit.
c. Ceirefully unsweat remaining tubing stubs when
necessary. Oil can ignite when exposed to torch
flame.
PRESTARTUP PROCEDURES
Proceed as follows to inspect and prepare the unit for initial
startup:
1. Remove all access panels.
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 and handling damages such as
broken lines, loose parts, disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections
and on unit base. Detecting oil generally indicates a
refrigerant leak. Leeik-test all refrigerant tubing
connections using electronic leak detector, halide
torch, or liquid-soap solution. If refrigerant leak
is detected, see “Refrigerant Leaks” section on
page 9.
c. Inspect all field- and factory-wiring connections. Be
sure that connections are completed and tight.
d. Inspect coil fins. If damaged during shipping and
handling, carefully straighten fins with a fin comb.
4. Verify the following conditions:
a. Make sure that outdoor fan blade is correctly posi­
tioned in fan orifice. Blades should clear fan motor
by no more than 1/4 in. The fan blade hub should be
flush with end of motor shaft.
b. Meike sure that air filter(s) is in place.
c. Make sure that condensate drain pan and trap are
filled with water to ensure proper drainage.