Vollrath Stoelting O431, Service Manual

Page: 44 / 75

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5.8 SOLENOID
Solenoid valves are installed on the liquid and suction lines
of each freezing cylinder evaporator and on the liquid line
of the cab evaporator (Refer to Figure 5-13). A solenoid
valve has a magnetic coil that, when energized, lifts a
plunger and allows refrigerant to
fl ow. The solenoids are
activated by the IntelliTec control and determine which
evaporator receives refrigeration.
The suction line solenoid prevents refrigerant
fl ow in the
evaporator when the suction pressure drops due to the
operation of the other evaporators in the system.
ACTIVATING THE SOLENOID VALVES
A. Turn the Main Power OFF/ON switch and both
Freezing Cylinder OFF/ON switches to the OFF
position.
B. Locate the compressor contactor behind the
header panel and disconnect the red wire #90.
C. Wrap electrical tape around wire to insulate it.
D. Remove belts from the pulley to allow drive motor
to spin freely.
E. Connect power to the machine.
F. Turn the Main Power OFF/ON switch and Freezing
Cylinder OFF/ON switches to the ON position.
G. Press the Push To Freeze buttons on the IntelliTec
control. This will energize the solenoid valves.
SOLENOID TESTING
When activated, a solenoid coil produces a magnetic fi eld.
This fi eld can be detected by placing the tip of a metal
screwdriver close to the retaining screw on the solenoid
coil. The retaining screw will like as a magnet and pull on
the screwdriver tip. Additionally, the solenoid will make a
clicking sound when activated.
SOLENOID MAGNETIC COIL REMOVAL
A. Remove the side panel.
B. Disconnect the electrical wires.
C. Remove the retaining screw from the top of the
solenoid and pull the magnetic coil off.
SOLENOID MAGNETIC COIL INSTALLATION
To replace the magnetic coil, perform the following pro-
cedures:
A.
Connect the two electrical wires to the magnetic
coil.
B. Push the coil on to the solenoid valve stem.
C. Make sure there is not any foam insulation between
the valve coil and valve body. Trim any excess
insulation.
D. Install the retaining screw onto top of coil.
SOLENOID VALVE REMOVAL
A. Recover refrigerant charge per instructions in
Section 5.2.
B. Remove insulation around valve and attached
refrigeration lines.
C. Apply heat sinks (wet cloth) to the insulated
refrigerant lines near the valve.
D. Leave a port open to prevent pressure buildup
during solenoid removal.
E. Identify and disconnect the two wires from the
solenoid coil.
F. Remove the retainer holding the coil to the solenoid
body and remove the coil.
G. Unsweat the solenoid and remove.
SOLENOID VALVE REPLACEMENT
To replace the solenoid, perform the following procedures:
A.
Position the new solenoid with the arrow pointing
toward the direction of
fl ow.
B. Apply a heat sink (wet cloth) to the solenoid valve.
C. With the suction and discharge ports open, braze
the solenoid into the system using appropriate
brazing material.
D. Remove the heat sink from the valve.
E. Replace insulation around valve.
F. Replace the fi lter drier. Refer to Section 5.8 for
details.
G. Evacuate and recharge system per instructions
in Section 5.2.
Figure 5-13 Solenoid Valve
CAUTION
When replacing the solenoid, a heat sink (wet cloth)
must be used to prevent damage to the valve.