Thermo King SB-190 30, Manual

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Refrigeration Service Operations (Rev. 12/03)
79
CAUTION: Unscrew the large nut. Do not
unscrew the small nut.
WARNING: If the ETV is stuck in the closed
position, much of the refrigerant charge may be
trapped in the evaporator. If you hear refriger-
ant begin to flow through the valve when the
stepper motor and piston assembly are loos-
ened, unscrew the stepper motor and piston
assembly no more than four turns and check
the suction (low side) pressure on the gauge
manifold. If the suction pressure has increased
from the pressure to which it was equalized
after the low side pump down, refrigerant is
trapped and must be recovered. Screw the step-
per motor and piston assembly back into the
valve body. Attach a refrigerant recovery device
to the service port on the receiver tank outlet
valve. Midseat the receiver tank outlet valve,
and recover the refrigerant charge. The stepper
motor and piston assembly may then be
removed.
6. If the complete ETV assembly is being replaced, unsol-
der and remove the valve body. It may be necessary to
unsolder the tubes above or below the valve body to
obtain enough clearance to remove the valve body.
Note the position of the valve body so the new one will
be placed in the same position. The new ETV could
interfere with the evaporator access panel if it is not
placed in the same position as the old one.
Installation
1. If an ETV service kit (stepper motor and piston assem-
bly) is being installed, go to step 2. If a complete ETV
assembly is being installed, proceed as follows:
a. Remove the stepper motor and piston assembly
from the valve body on the new ETV assembly.
b. Clean the tubes for soldering.
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 direc-
tion 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 pis-
ton retracts to open and extends to close.
NOTE: The ETV cannot be opened manually. See the
following CAUTION.
1. Stepper Motor 4. Large Nut
2. Harness Connector 5. Valve Body
3. Clip
Electronic Throttling Valve
ARA168
2
1
3
4
5