Carrier 38AUM Series Installation, Operation & Maintenance Manual page 14

When connecting the field tubing to the 38AU 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 — Evacuate and dehydrate the connected refrigeration system(s) (excluding the 38AUM
unit) to 500 microns using a two-stage vacuum pump attached to the service ports outside the 38AU service valves,
following description in GTAC II, Module 4, System Dehydration.
Failure to follow this warning could cause personal injury, death and/or equipment damage.
Puron® (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.
This unit is designed for use with Puron (R-410A) refrigerant. Do not use any other refrigerant in this system.
Puron (R-410A) refrigerant is provided in pink (rose) colored cylinders. These cylinders are available with and without
dip tubes; cylinders with dip tubes will have a label indicating this feature. For a cylinder with a dip tube, place the
cylinder in the upright position (access valve at the top) when removing liquid refrigerant for charging. For a cylinder
without a dip tube, invert the cylinder (access valve on the bottom) when removing liquid refrigerant.
Because Puron (R-410A) refrigerant is a blend, it is strongly recommended that refrigerant always be removed from
the cylinder as a liquid. Admit liquid refrigerant into the system in the discharge line. If adding refrigerant into the
suction line, use a commercial metering/expansion device at the gauge manifold; remove liquid from the cylinder, pass
it through the metering device at the gauge set and then pass it into the suction line as a vapor. Do not remove Puron
(R-410A) refrigerant from the cylinder as a vapor.
Preliminary Charge — Before starting the unit, charge R-410A liquid refrigerant into the high side of each 38AUM
circuit through the liquid service valve(s). The amount of refrigerant added must be compatible with the operating
charge listed in Table Piping Recommendation for LINEAR line length LESS the factory charge quantity (if factory
shipping charge has not been removed). See example below.
Note: See section "Adjust Refrigerant Charge" for details on refrigerant charge adjustment.
Allow high and low side pressures to equalize. If pressures do not equalize readily, charge R-410A vapor (using
special service manifold with expansion device) into the suction line service port for the low side of system to assure
charge in the evaporator. Refer to GTAC II, Module 5, Charging, Recover, Recycling, and Reclamation for liquid
charging procedures.
Fig: - Typical Piping Connection Assembly
WARNING
UNIT OPERATION AND SAFETY HAZARD
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