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FIELD REFRIGERANT ACCESS PORTS
Field service access to refrigerant pressures is through the access
ports located at the service valves (see Fig. 18-19). These ports are
1/4 in. SAE Flare couplings with Schrader check valves and ser-
vice caps. Use these ports to admit nitrogen to the field tubing
during brazing, to evacuate the tubing and evaporator coil, to ad-
mit 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.-lb
(23-34 N-cm).
OFM1
OFM2
OFM3
Service
Valves
Fig. 18 — 38AUQ*16 Exterior
OFM4
OFM3
Service
Valves
Fig. 19 — 38AUQ*25 Exterior
OUTDOOR COIL METERING DEVICES
The metering devices are multiple fixed-bore devices (Acutrol™)
swaged into the horizontal outlet tubes from the liquid header, lo-
cated at the entrance to each evaporator coil circuit path. These are
non-adjustable. Service requires replacing the entire liquid header
assembly.
To check the indoor coil, disconnect the supply fan signal
(A04-A06 direct-drive fans) or contactor (IFC) coil, then start the
circuit in a Cooling Mode (jumper R to Y1 or Y2) and observe the
frosting pattern on the face of the indoor coil. A frost pattern
should develop uniformly across the face of the indoor coil start-
ing at each tube at the Acutrol nipple locations.
To check the outdoor coil, disconnect the outdoor fan motor. Start
the circuit in a Heating Mode (jumper R to W1 or W2) and ob-
serve the frost pattern on the face of the outdoor coil.
Failure to develop frost at an outlet tube can indicate a plugged or
a missing orifice.
REFRIGERANT SYSTEM PRESSURE ACCESS PORTS
There are two access ports in each circuit - on the suction tube
near the compressor and on the discharge tube near the
compressor. (See Fig. 20-21.) 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 recepta-
cle base brazed to the tubing and an integral spring-closed check
valve core screwed into the base. (See Fig. 22.) This check valve
is permanently assembled into this core body and cannot be ser-
viced 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 re-
frigerant charge. Apply compressor refrigerant oil to the check
valve core's bottom o-ring. Install the fitting body with
96 ± 10 in.-lb (1085 ±23 N-cm) of torque; do not overtighten.
OFM1
OFM2
Circuit
2
LOC
23
Outdoor Coil
High Flow
Access Ports
Defrost
Thermostat
(DFT)
Compressor 2
Fig. 20 — 38AUQ*16 Interior
Outdoor Coil
Defrost
Thermostat
(DFT)
HPS
Circuit 1
LOC
Compressor 1
HPS
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