62-11848
5-10
5.12.1
Replacing expansion valve
a. Remove the refrigerant charge. Refer to
b. Remove insulation from the expansion valve bulb and then remove the bulb from the suction line.
c. Loosen flare nut and disconnect equalizer line from expansion valve.
d. The txv bulb is located below the center of the suction line. This area must be clean to ensure positive bulb
contact. Strap the bulb to the suction line and insulate both.
e. Braze the equalizer tubes to the expansion valve.
f. Evacuate, dehydrate and recharge the unit. Refer to
and
.
.
5.12.2
Measuring Superheat
a. Remove insulation from the expansion valve bulb and suction line. Refer to
b. Loosen one TXV bulb clamp and make sure the area under the clamp (above TXV bulb) is clean.
c. Place the thermocouple above (parallel to) the TXV bulb and then secure the loosened clamp making sure
both bulbs are firmly secured to the suction line as shown in
d. Connect an accurate gauge to the ¼” port on the suction service valve.
e. Run the unit until stabilized at -4°F (-20°C) box temperature.
f. From the temperature/pressure chart (
), determine the saturation temperature corresponding to
the evaporator outlet pressure.
g. Note the temperature of the suction gas at the expansion valve bulb.
h. Subtract the saturation temperature determined in step f from the average temperature measured in Step g.
The difference is the superheat of the suction gas. Refer to
for superheat setting.
i. If required, adjust superheat by turning the adjusting screw located under the cap on the side of the valve.
Figure 5.7 Thermostatic Expansion Valve Bulb and Thermocouple
5.13 DIAGNOSTIC TOOL
NOTE
The Cab Command diagnostic tool comes with two jumpers. These are not applicable to the 20X sys-
tem and should not be used in this application.
Figure 5.8 CAB Command Diagnostic Tool (CTD P/N 07-00440-00)
Nut and Bolt (Clamp)
Suction Line (end view)
TXV Bulb Clamp
TXV Bulb
Thermocouple
REMOTE
TOOL
PRIMARY
TOOL
