Refrigeration Service Operations
152
2. Lubricate the piston and threads on the new
stepper motor and piston assembly with
refrigeration oil.
3. Screw the new stepper motor and piston
assembly into the valve body.
4. Torque the nut to approximately 118 ft-lb
(160 N•m). Hold the valve body with backup
wrench to prevent damage to the refrigeration
tubing.
5. Connect the ETV harness to the main wire
harness at the four-pin connector.
6. Pressurize the low side and test for leaks.
7. If no leaks are found, evacuate the low side.
8. Install the evaporator access panels.
9. Open the refrigeration valves and place the
unit in operation.
Reassembly of Piston and Stepper Motor
Use the following procedure to reassemble the
piston and stepper motor if the piston has
accidentally been turned off of the threaded shaft
of the stepper motor.
1. Disassemble the stepper motor and piston
assembly by unscrewing the stepper motor
(small hex) from the piston nut (large nut).
2. Insert the piston into the piston nut. You must
align the rectangular shaft on the piston with
the rectangular hole in the piston nut to allow
the piston to be inserted into the piston nut.
3. Push the piston into the piston nut until the
end of the rectangular shaft is about even with
the top of the piston nut.
4. Make sure the copper washer is in place in the
top of the piston nut.
5. Place the threaded shaft of the stepper motor
into the rectangular shaft of the piston and
turn the piston and piston nut onto the
threaded shaft of the stepper motor.
6. When the threads in the top of piston nut reach
the threads on the bottom of the stepper motor,
carefully continue to turn the piston and piston
nut onto the stepper motor. Make sure that the
copper washer is in place and take care to
avoid cross threading the fine threads on the
stepper motor and in the top of the piston nut.
1.
Piston
2.
Rectangular Shaft on Piston
3.
Piston Nut
4.
Copper Washer
5.
Threaded Shaft of Stepper Motor
6.
Stepper Motor
Figure 237: Stepper Motor and
Piston Assembly Components
1
2
3
4
5
6
1.
Align Rectangular Shaft on Piston
with Rectangular Hole in Piston Nut
Figure 238: Insert Piston into Piston Nut
1.
Position End of Rectangular Shaft
about Even with Top of Piston Nut
Figure 239: Push Piston into Piston Nut
1
1
