Carrier 38AUZ*07 Series Installation, Start-Up And Service Instructions Manual page 52

LIQUID LINE
SIZE (in.)
3
/
8
1
/
2
5
/
8
38AUD units require TWO sets of parts.
Select the filter driers for maximum unit capacity and
minimum pressure drop. Complete the refrigerant piping
from the indoor unit to the outdoor unit before opening
the liquid and suction lines at the outdoor unit.
INSTALL LIQUID LINE SOLENOID VALVE —
It is recommended that a solenoid valve be placed in the
main liquid line (see Fig. 8) between the condensing unit
and the evaporator coil. Locate the solenoid valve at the
outlet end of the liquid line, near the evaporator coil
connections, with flow direction arrow pointed at the
evaporator coil. Refer to Table 7. (A liquid line solenoid
valve is required when the liquid line length exceeds 23 m
[75 ft].) This valve prevents refrigerant migration (which
causes oil dilution) to the compressor during the off cycle,
at low outdoor ambient temperatures. Wire the solenoid in
parallel with the compressor contactor coil (see Fig. 8).
This means of electrical control is referred to as solenoid
drop control.
TXV
SENSING
BULB
AIRFLOW
15 DIAMS
10
MIN
DIAMS
TXV
SENSING
BULB
AIRFLOW 15 DIAMS
10
MIN
DIAMS
SUCTION
CIRCUIT 1
SUCTION
CIRCUIT 2
Dual Circuit Coil Piping Configuration
For two circuit condensing units
Fig. 8 - - Location of Sight Glasses and Filter Driers
Typical 38AUD Systems
CAPACITY CONTROL LIQUID LINE SOLENOID
VALVE Evaporator capacity control via liquid solenoid
valve is not recommended for use with 38AUD models.
MAKE PIPING CONNECTIONS — Piping connections
at the 38AUD unit are ball valves with stub tube
extensions. Do not open the unit service valves until all
interconnecting tube brazing as been completed.
Table 7 – Refrigerant Specialties Part Numbers.
LIQUID LINE
SOLENOID VALVE (LLSV)
EF680033
EF680035
EF680036
EQUALIZER LINE
TXV
CKT 2
8 DIAMS
MIN
SIGHT
GLASSES
LIQUID LINE
SOLENOID VALVE
FILTER
CIRCUIT 2
DRIERS
TXV
CKT 1
8 DIAMS
MIN
LIQUID LINE
SOLENOID VALVE
CIRCUIT 1
C10072
LLSV SIGHT
COIL GLASS
EF680037 KM680008
EF680037 KM680004
EF680037 KM680005
The stub tube connections include
fittings with Schrader valve cores (see Fig. 9). Before
making any brazed connections to the unit service valves,
remove both Schrader valve caps and cores and save for
re-installation. Connect a source for nitrogen to one of
these service fittings during tube brazing to prevent the
formation of copper oxides inside the tubes at brazed
joints.
Factory
High-Flow
Access Port
Service Valve
with Stem Cap
Fig. 9 - - Typical Piping Connection Assembly
When connecting the field tubing to the 38AUD service
valves, wrap the valves in wet rags to prevent overheating
Pressure-test all joints from outdoor unit connections over
to the evaporator coil, using nitrogen as pressure and with
soap-and-bubbles.
When pressure-testing is completed, remove the nitrogen
source at the outdoor unit service valves and re-install the
two Schrader valve cores. Torque the cores to 23-34 N-cm
(2-3 in-lbs).
EVACUATION/DEHYDRATION
dehydrate the connected refrigeration systems (excluding
the 38AUD unit) to 500 microns using a two-stage
vacuum pump attached to the service ports outside the
38AUD service valves, following description in GTAC II,
Module 4, System Dehydration.
WARNING
!
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
Puron R (R- - 410A) refrigerant systems operate at
higher pressure than standard R- - 22 systems. Do not
use R- - 22 service equipment or components on Puron
refrigerant equipment.
12
FILTER
DRIER
KH43LG091
KH43LG085
KH43LG087
1
/ -in SAE service
4
Field Service
Access Port
(Schrader core)
Sweat
Connection
C10073
— Evacuate and