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5
Refrigerant Service Ports
Each independent refrigerant system has a total of 3
Schrader-type service gauge ports per circuit. One port is located
on the suction line, one on the compressor discharge line, and one
on the liquid line. Be sure that caps on the ports are tight.
Crankcase Heater(s)
Compressor crankcase heater operation varies depending on the
unit size and type. In general for all units, the crankcase heaters
are energized if there is power to the unit, the compressor is not
operating, and the ambient temperature is below 75
_
F.
IMPORTANT
: Unit power must be on for 24 hours prior to
start--up. Otherwise, damage to compressor may result.
Compressor Rotation
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
Improper wiring will cause compressor stoppage and alarm.
Correct wiring by switching leads as indicated below.
CAUTION
!
On 3-phase units, it is important to be certain the compressors are
rotating in the proper direction. To determine whether or not
compressors are rotating in the proper direction, use a
phase-rotation meter on the unit input power to check for
L1-L2-L3 or clockwise rotation or use the Service Test mode to
energize a compressor. If the compressor is rotating in the wrong
direction, the controls will stop the compressor and display alarm
for “Circuit x Failure to Pressurize,” where x is the corresponding
A, B or C compressor circuit.
NOTE
: Indoor or outdoor fan rotation direction may not indicate
proper input power phase sequence, as some 3-phase units use
single-phase fan motors.
To correct the wrong compressor rotation direction, perform the
following procedure:
1. Turn off power to the unit and lock out the power.
2. Switch any two of the incoming unit power leads.
3. Turn on power to the unit.
4. Verify corrected compressor rotation.
Orifice Change (48PG Only)
This unit is factory assembled for heating operation using natural
gas at an elevation from sea level to 2000 ft.
Use accessory high altitude kit when installing this unit at an
elevation of 2000 to 7000 ft. For elevations above 7000 ft, refer
to High Altitude section to identify the correct orifice size for the
elevation. Purchase these orifices from your local Carrier dealer.
Follow instructions in accessory Installation Instructions to install
the correct orifices.
Use accessory LP (liquid propane) gas conversion kit when
converting this unit for use with LP fuel usage for elevations up
to 7000 ft. For elevations above 7000 ft, refer to High
Altitude section to identify the correct orifice size for the
elevation. Purchase these orifices from your local Carrier dealer.
Follow instructions in accessory Installation Instructions to install
the correct orifices.
Power Supply
All 208/230-v units are factory wired for 230-v power supply. If
the 208/230-v unit is to be connected to a 208-v power supply,
the transformers (TRAN1, TRAN2 and TRAN3) must be rewired
by moving the wire from the 230-volt connection and moving to
the 200-volt terminal on the primary side of the transformer.
Refer to unit label diagram for additional information.
Internal Wiring
Check all electrical connections in unit control boxes; tighten as
required.
Evaporator Fan
Fan belt and variable pulleys are factory-installed. See Tables
3-78 for Fan Performance Data. Be sure that fans rotate in the
proper direction. See Table 79 for air quantity limits. See Table 80
for Evaporator Fan Motor Specifications. See Table 81 for fan
rpm at various motor pulley settings. See Tables 82--84 for static
pressure drop of options and accessories. To alter fan
performance, see Evaporator Fan Performance Adjustment
section.
Condenser Fans and Motors
Condenser fans and motors are factory set. Refer to
Condenser-Fan Adjustment section as required.
Return--Air Filters
Check that correct filters are installed in filter tracks (see Physical
Data table in Installation Instructions). Do not operate unit
without return-air filters.
NOTE
: For units with 4-in. filter option, units are shipped with
standard 2-in. filters. To install 4-in. filters, the filter spacers must
be removed.
Outdoor--Air Inlet Screens
Outdoor-air inlet screens must be in place before operating unit.
Air Baffles
The 48/50PG units with Humid-MiZer
™
option are equipped
with Motormaster
®
control to maintain adequate discharge
pressure for proper unit operation during low ambient operation.
Field-fabricated and installed wind baffles may be required. See
Optional Humidi-MiZer Dehumidification System section.
Accessory Installation
Check to make sure that all accessories including space
thermostats and sensors have been installed and wired as required
by the instructions and unit wiring diagrams.
C06323
Fig. 4
---
Field Gas Piping
Gas Heat (48PG Only)
Verify gas pressures before turning on heat as follows:
1. Turn off field-supplied manual gas stop, located external
to unit.
2. Connect pressure gauge to supply gas tap, located on
field-supplied manual shutoff valve. (See Fig. 4.)
3. Connect pressure gauge to manifold pressure tap.
4. After the unit has run for several minutes, verify the
supply gas pressure is between 5.5 in. wg to 13.0 in. wg,
and the manifold pressure is 3.50 in. wg on sizes 03-14
and 3.00 on size 16. If manifold pressure must be adjusted,
refer to Gas Valve Adjustment section.
48/
50P
G
C
03
--
16