Thermo King SB-210, Manual

Page: 123 / 159

Refrigeration Service Operations
123
c. Place the new valve body (and any tubes
that were removed) in the same position
from which the old one was removed. The
new ETV could interfere with the
evaporator access panel if it is not placed
in the same position as the old one. The
arrow on the valve body must point up,
which is the direction of refrigerant flow
from the evaporator to the heat exchanger.
d. Solder the tubing connections. Use a heat
sink on the valve body to prevent damage.
e. Allow the valve body to cool before
installing the stepper motor and piston
assembly.
2. Check the stepper motor and piston assembly
to make sure the piston is an open position. In
an open position the bottom edge of the piston
is 0.75 to 1.25 in. (19 to 32 mm) from the
bottom edge of the brass nut. The piston
retracts to open and extends to close.
NOTE: The ETV cannot be opened
manually. See the following CAUTION.
3. Lubricate the piston and threads on the new
stepper motor and piston assembly with
refrigeration oil.
4. Screw the new stepper motor and piston
assembly into the valve body.
5. Torque the nut to approximately 100 ft-lb
(136 N•m). Hold the valve body with backup
wrench to prevent damage to the refrigeration
tubing.
6. Connect the ETV harness connector to the
stepper motor. Take care when making the
connection. The connector attaches to the
ETV in only one position.
7. Install the clip and secure it with a band wrap.
8. Pressurize the low side and test for leaks.
9. If no leaks are found, evacuate the low side.
10. Install the evaporator access panels.
11. Open the refrigeration valves and place the
unit in operation. Check the operation of the
ETV.
1. Bottom Edge of Brass Nut
2. Bottom Edge of Piston
Figure 109: Stepper Motor and Piston Assembly
with Piston in Fully Open Position
ARA167
1
2
0.75 in.
(19 mm)
CAUTION: The ETV may stick in the
closed position if the stepper motor and
piston assembly is installed with the piston
in the closed position. In the closed
position the bottom edge of the piston is
1.5 in. (38 mm) from the bottom edge of
the brass nut. If there is any doubt about
the position of the piston, connect the
ETV harness to the stepper motor and
piston assembly and use the evacuation
mode in the Service Test Mode to place the
piston in the fully open position. Refer to
the SR-2 Microprocessor Controller
Diagnostic Manual TK 51587 for
information about placing the unit in the
evacuation mode. After placing the piston
in the fully open position, disconnect the
ETV harness from the stepper motor and
piston assembly.
CAUTION: Tighten the large nut. Do not
tighten the small nut.