26
Step 9 — Wind Baffles for Low Ambient Control
Models 38AUZB and 38AUDB include the factory installed
32LT Motormaster Low Ambient Control. Model 38AUDC
(with hot gas bypass option) also includes the 32LT
Motormaster Low Ambient Control as a standard feature.
Units with 32LT Motormaster control require the addition
of wind baffles to e nsure full range low ambient
operation. Material data a nd dime nsions for wind baffles
are included in the Appendix C section, Low Ambie nt
Control, starting on page 50. Fabricate the wind baffles
and mount per instructions.
PRE-START-UP
IMPORTANT : Before beginning Pre-Start-Up or
Star t-U p , review Start-U p Checklis t at the back of this
book. The Checklist assures proper start-up of a unit
and provides a record of unit condition, application
requirements, system information, and operation at
initial start-u p.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
dama ge.
Do not attempt to start the condensing unit, even
momentarily, until the following steps have been
completed. Compressor damage may result.
CAUTION
!
System Check
1. The electrical power source must agree with the unit’s
name plate rating.
2. Check all air handler( s ) and other equipment auxiliary
components. Consult the manufacturer’s instructions re-
garding any other equipment connected to the condens-
ing unit. If the u nit has field-ins talled access or ies , be
sure all are properly installed and correctly wired. If
used, the airflow switch must be properly installed.
3. Check tightness of all electrical connections.
4. Be sure liquid line and low side of the syste m are
properly leak checked and dehydrated.
5. Be sure the unit is properly charged. See “Preliminary
Charge”, below.
6. Open the liquid line and suction line service valves.
7. The crankcase heater must be firmly attached to the
compressor crankcase. Be sure the crankcase is warm
(heater must be on for 24 hours before starting
compressor).
Turn On Crankcase Heater —
Turn on the crankcase heater for 24 hours before starting
the unit to be sure all the ref rigerant is out of the oil.To
energize the crankcase heater, proceed as follows:
1. Set the space thermostat set point above the space
temperature so there is no demand for cooling.
2. Close the field disconnec t.
Preliminary Charge —
Before starting the unit, charge liquid refrigerant into the
high side of the system through the liquid service valve.
The amount of refrigerant added must be at least 80% of
the operating charge listed in the Physical Data table
(Table s 1A through 2B, pages 7 through 10). Allow high
and low side pressures to equalize before starting
compressor. If pressures do not equalize readily, charge
vapor on low side of system to assure charge in the
evapora tor. Refer to GTAC II, Module 5, Charging,
Recover, Recycling, and Reclamation for liquid charging
procedure s.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
dama ge.
Prior to starting compressor, a preliminary charge of
refrigerant must be added to avoi d possible
compressor damage.
CAUTION
!
START-UP
38AU Units: The compressor crankcase heater must be on
for 24 hours before start-up. After the hea ter has been on
for 24 hours, the unit can be started. If no time elapsed
since the preliminary charge step was completed, it is
unnece ssary to wait the 24-hour period.
Preliminary Checks
1. Check that electric power supply agrees with unit
nameplate data.
2. Verify that the compressor crankcase heater is se-
curely in place.
3. Check that the compressor crankcase heater has been
on at least 24 hours.
4. Recheck for leaks using the procedure outlined in the
Pre-Start-Up section, Leak Test and Dehydrat ion. If
any leaks are detected, repair as required. Evacuate
and dehydrate as described in the Leak Test and De-
hydration section.
5. Ensure that the preliminary charge has been added as
described in the Pre-Start-Up section, Preliminary
Charge.
6. All internal wiring connections must be tight, and all
barriers and covers must be in place.
Note: The 38AU units are factory charged with the
required amount of oil. If recharging in required, use
Emkarate RL 32-3MAF for the 38AU units.
Compressor Rotation —
On 3--phase units with scroll compres s or s , it is important to
be certain that the compressor is rotating in the proper
direction. 38AU units are equipped with a Comfort Alert
Diagnostic Module (CADM). Alert Code 7 indicates reverse
power phasing.
38AU
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