Carrier 38AUM Series Installation, Operation & Maintenance Manual page 23

Refrigeration System
This system uses Puron® refrigerant which has higher pressures than R-22 and other refrigerants. No other refrigerant
may be used in this system. Gage set, hoses, and recovery system must be designed to handle Puron. If you are
unsure consult the equipment manufacturer.
Compressor Oil
The compressor in a Puron system uses a Polyolester (POE) oil. This oil is extremely hygroscopic, meaning it absorbs
water readily. POE oils can absorb 15 times as much water as other oils designed for HCFC and CFC refrigerants.
Take all necessary precautions to avoid exposure of the oil to the atmosphere.
Field Refrigerant Access Ports — Field service access to refrigerant pressures is through the access ports located
at the service valves. These ports are 1/4-in SAE Flare couplings with Schrader check valves and service caps. Use
these ports to admit nitrogen to the field tubing during brazing, to evacuate the tubing and evaporator coil, to admit
initial refrigerant charge into the low-side of the system and when checking and adjusting the system refrigerant
charge. When service activities are completed, ensure the service caps are in place and secure; check for leaks. If the
Schrader check valve must be removed and re-installed, tighten to 2-3 in-lbs (23-34 N-cm).
Factory High-Flow Access Ports — There are two additional access ports in the system – on the suction tube
between the compressor and the suction service valve and on the liquid tube near the liquid service valve. These are
brass fittings with black plastic caps. The hose connection fittings are standard 1/4-in SAE Male Flare couplings. The
brass fittings are two-piece High Flow valves, with a receptacle base brazed to the tubing and an integral spring-
closed check valve core screwed into the base. (See Fig. 35) This check valve is permanently assembled into this
core body and cannot be serviced separately; replace the entire core body if necessary. Service tools are available
from RCD that allow the replacement of the check valve core without having to recover the entire system refrigerant
charge. Apply compressor refrigerant oil to the check valve core's bottom o-ring. Install the fitting body with 96 ±-10 in-
lbs (1085 ±23 N-cm) of torque; do not overtighten.
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
Fig. 35 - CoreMax Access Port Assembly
CAUTION
CAUTION
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