Carrier WeatherMaster 50HC04, Service And Maintenance Instructions, Page: 14 / 132

14
flow causes the leaving evaporator temperature to
decrease. This lowers the pressure on the diaphragm and
closes the pin. The refrigerant flow is effectively stabilized
to the load demand with negligible change in superheat.
Replacing TXV
1. Recover refrigerant.
2. Remove TXV support clamp using a 5 /
l6
-in. nut driver.
3. Remove TXV using a wrench and an additional wrench on
connections to prevent damage to tubing.
4. Remove equalizer tube from suction line of coil. Use file
or tubing cutter to cut brazed equalizer line approximately
2 inches above suction tube.
5. Remove bulb from vapor tube inside cabinet.
6. RInstall the new TXV using a wrench and an additional
wrench on connections to prevent damage to tubing while
attaching TXV to distributor.
7. Attach the equalizer tube to the suction line. If the coil has
a mechanical connection, then use a wrench and an addi-
tional wrench on connections to prevent damage. If the
coil has a brazed connection, use a file or a tubing cutter to
remove the mechanical flare nut from the equalizer line.
Then use a new coupling to braze the equalizer line to the
stub (previous equalizer line) in suction line.
8. Attach TXV bulb in the same location where the original
(in the sensing bulb indent) was when it was removed,
using the supplied bulb clamps. See Fig. 22.
9. Route equalizer tube through suction connection opening
(large hole) in fitting panel and install fitting panel in
place.
10. Sweat the inlet of TXV marked “IN” to the liquid line.
Avoid excessive heat which could damage the TXV valve.
Use quenching cloth when applying heat anywhere on
TXV.
Refrigerant System Pressure Access Ports
There are two access ports in the system: on the suction tube
near the compressor and on the discharge tube near the compres-
sor. 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 recep-
tacle base brazed to the tubing and an integral spring-closed
check valve core screwed into the base. See Fig. 23. This check
valve is permanently assembled into this core body and cannot
be serviced separately; replace the entire core body if neces-
sary. Service tools are available from RCD that allow the re-
placement of the check valve core without having to recover
the entire system refrigerant charge. Apply compressor refrig-
erant oil to the check valve core’s bottom o-ring. Install the fit-
ting body with 96 ± 10 in.-lb (10.85 ± 1.1 Nm) of torque; do
not over-tighten.
Fig. 22 — TXV Valve and Sensing Bulb Location
Fig. 23 — CoreMax
1
Access Port Assembly
TXV SENSING
BULB
CLAMP
THERMAL EXPANSION
(TXV) VALVE
SENSING BULB INSULATION REMOVED FOR CLARITY
1. CoreMax is a registered trademark of Fastest, Inc.
5/ 8
” HEX
0.47
3 0°
0.596
1/2-20 UNF RH
1/2
” HEX
45°
WA S HER
O-RING
7/16-20 UNF RH
DEPRE SS OR PER AHRI 720
+.01/-.0 3 5
FROM FACE OF BODY
Thi s su rf a ce provide s a met a l to met a l s e a l when
torq u ed into the s e a t. Appropri a te h a ndling i s
req u ired to not s cr a tch or dent the su rf a ce.
S EAT CORE
(P a rt No. EC 3 9EZ067)