Stoelting F431 Service Manual page 49

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 A SOLENOID
To open a solenoid, follow these steps:
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 brown 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 button the IntelliTec
control. This will energize the solenoid valve.
SUCTION LINE SOLENOID TESTING
To check for leaking valve seats, follow the procedure
outlined below.
Machine barrels must NOT contain frozen product
for this test.
A. Turn the Main Power OFF/ON switch and both
Freezing Cylinder OFF/ON switches to the OFF
position.
B. To check the suction line solenoid valve seats,
the liquid line solenoid must remain open.
C. Attach a gauge to the Schrader valve after the
TXV of the side being tested.
D. Place the Main Power OFF/ON switch to the ON
position.
E. Place the opposite side Freezing Cylinder OFF/
ON switch to the ON position.
If checking the solenoid on the left side, place the
right side Freezing Cylinder OFF/ON switch to the
ON position. For the right side, place the left side
switch to the ON position.
F. Start a freezing cycle of the opposite side by
pressing the Push To Freeze button or by pulling
the spigot handle.
G. If the pressure drops more than 3 psi in 30 seconds
on the side being tested, the suction line solenoid
valve seat leaks and should be replaced. Repeat
the procedure for the other side.
NOTE
NOTE
LIQUID LINE SOLENOID TESTING
The following test will check if a liquid line solenoid has
a leaking valve seat. The power to the solenoid is dis-
connected and refrigerant fl ow is monitored through the
system. If the valve seat does not leak, the suction pres-
sure during the test will read the same as the pressure
when only the cab is running.
A. Turn the Main Power OFF/ON switch and both
Freezing Cylinder OFF/ON switches to the OFF
position.
B. Disconnect a terminal on each of the liquid line
solenoids.
C. Protect the terminal end of the disconnected
electrical line with a piece of electrical tape.
D. Attach gauges to the Schrader valves after the
evaporators on the suction line.
E. Turn the Main Power OFF/ON switch and both
Freezing Cylinder OFF/ON switches to the ON
position
F. Start a freezing cycle by pressing the Push To
Freeze button or by pulling on the spigot handles.
G. The gauges should show approximately 18 psig
after 1 minute.
H. Watch the pressure in both freezing cylinders.
The freezing cylinder with the greatest pressure
rise may have a leaking valve seat.
SOLENOID MAGNETIC COIL REMOVAL
A. Remove the side panel.
B. Disconnect the electrical wires.
C. Remove the retainer 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 isn't any foam insulation between
the valve coil and valve body. Trim any excess
insulation.
D. Install retainer 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.
41