Thermo King SB-190 30, Manual

Page: 90 / 119

Refrigeration Service Operations (Rev. 12/03)
80
CAUTION: The ETV may stick in the closed posi-
tion 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
[EVAC] mode in the Service Test Mode to place the
piston in the fully open position. Refer to Service
Procedure A34A, the Service Test Mode, in the
THERMOGUARD
µ
P-VI Microprocessor Control-
ler Diagnosis Manual TK 50566 for information
about placing the unit in the evacuation [EVAC]
mode. After placing the piston in the fully open
position, disconnect the ETV harness from the step-
per motor and piston assembly.
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.
CAUTION: Tighten the large nut. Do not
tighten the small nut.
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 oper-
ation. Check the operation of the ETV.
COMPRESSOR OIL FILTER CHANGE
This unit is equipped with a compressor oil filter. The com-
pressor oil filter should be changed when the drier is
replaced.
1. Pump down the low side and equalize the pressure to
slightly positive.
2. Front seat the discharge and suction service valves.
Remove the remaining refrigerant from the compressor.
3. Disconnect the oil lines from the compressor oil filter.
Hold the oil filter with back-up wrench on the hex
behind the ORS fitting.
4. Remove the clamp and the compressor oil filter.
1. Bottom Edge of Brass Nut
2. Bottom Edge of Piston
Stepper Motor and Piston Assembly
with Piston in Fully Open Position
ARA167
1
2
0.75 in
(19 mm)