Start-Up, General; Unit Preparation; Return-Air Filters; Outdoor-Air Inlet Screens - Carrier WeatherExpert 50LC 07 Series Service And Maintenance Instructions

WARNING
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could cause personal injury or
death.
Relieve pressure and recover all refrigerant before system re-
pair or final unit disposal.
Wear safety glasses and gloves when handling refrigerants.
Keep torches and other ignition sources away from refriger-
ants and oils.
3. Make the following inspections:
a. Inspect for shipping and handling damages such as bro-
ken lines, loose parts, or disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections and
on unit base. Detecting oil generally indicates a refriger-
ant leak. Leak-test all refrigerant tubing connections
using electronic leak detector, halide torch, or liquid-
soap solution.
c. Inspect all field-wiring and factory-wiring connections.
Be sure that connections are completed and tight. Be
sure that wires are not in contact with refrigerant tubing
or sharp edges.
d. Inspect coil fins. If damaged during shipping and han-
dling, carefully straighten fins with a fin comb.
4. Verify the following conditions:
a. Make sure that condenser-fan blades are correctly posi-
tioned in fan orifice. See Condenser-Fan Adjustment
section for more details.
b. Make sure that return air filter(s) are in place.
c. Make sure that condensate drain trap is filled with water
to ensure proper drainage.
d. Make sure that all tools and miscellaneous loose parts
have been removed.

START-UP, GENERAL

Unit Preparation

Make sure that unit has been installed in accordance with installa-
tion instructions and applicable codes.

Return-Air Filters

Make sure correct filters are installed and clean prior to starting
unit (see Appendix B - Physical Data). Do not operate unit without
return-air filters.

Outdoor-Air Inlet Screens

Outdoor-air inlet screen must be in place before operating unit.

Compressor Mounting

Compressors are internally spring mounted. Do not loosen or re-
move compressor hold down bolts.

Internal Wiring

Check all electrical connections in unit control boxes. Tighten as
required.

Refrigerant Service Ports

Each unit system has two
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service ports: one on the suction line, and one on the compressor
discharge line. Be sure that caps on the ports are tight.
/ -in. SAE flare (with check valves)
4

Compressor Rotation

On 3-phase units with scroll compressors, it is important to be cer-
tain compressor is rotating in the proper direction. To determine
whether or not compressor is rotating in the proper direction:
1. Connect service gages to suction and discharge pressure
fittings.
2. Energize the compressor.
3. The suction pressure should drop and the discharge pressure
should rise, as is normal on any start-up.
If the suction pressure does not drop and the discharge pressure
does not rise to normal levels:
1. Note that the evaporator fan is probably also rotating in the
wrong direction.
2. Turn off power to the unit and install lockout tag.
3. Reverse any two of the unit power leads.
4. Re-energize to the compressor. Check pressures.
The suction and discharge pressure levels should now move to
their normal start-up levels.
NOTE: When the compressor is rotating in the wrong direction,
the unit will make an elevated level of noise and will not provide

cooling.

Cooling
Set space thermostat to OFF position. To start unit, turn on main
power supply. Set system selector switch at COOL position and
fan switch at AUTO. position. Adjust thermostat to a setting ap-
proximately 5°F (3°C) below room temperature. Both compres-
sors start on closure of contactors.
Check unit charge. Refer to Refrigerant Charge section.
Reset thermostat at a position above room temperature. Both com-
pressors will shut off. Evaporator fan will shut off after a
30 second delay. The supply fan and both compressors will shut
off.
To shut off unit, set system selector switch at OFF position. Reset-
ting thermostat at a position above room temperature shuts unit off
temporarily until space temperature exceeds thermostat setting.

Heating

To start unit, turn on main power supply.
Set system selector switch at HEAT position and set thermostat at
a setting above room temperature. Set fan at AUTO position.
First stage of thermostat energizes the first-stage electric heater el-
ements; second stage energizes second-stage electric heater ele-
ments, if installed. Check heating effects at air supply grille(s).
If electric heaters do not energize, reset limit switch (located on
evaporator-fan scroll) by pressing button located between termi-
nals on the switch.

To Shut Off Unit

Set system selector switch at OFF position. Resetting thermostat
at a position below room temperature temporarily shuts unit off
until space temperature falls below thermostat setting.

Ventilation (Continuous Fan)

Set fan and system selector switches at ON and OFF positions, re-
spectively. Evaporator fan operates continuously to provide con-
stant air circulation.

Electrical Connections

HACR
The amp rating of the HACR factory installed option is based on
the size, voltage, indoor motor and other electrical options of the
unit as shipped from the factory. If field-installed accessories are
added or changed in the field (i.e. electric heat, power exhaust,
ERV), the HACR may no longer be of the proper amp rating and
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