Vollrath Stoelting O431, Service Manual

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C. Install the compressor into the machine, fi tting
the base over the four bolt holes.
D. Install the four washers and nuts onto the bolts
and tighten securely.
E. Remove all tubing plugs from the replacement
compressor.
NOTE
The compressor plugs protect the compressor from
moisture in the air. Do not remove the plugs until
you are ready to install. The compressor must not
be opened to the atmosphere for more than 10
minutes.
F. Leave the suction and discharge ports open to
prevent pressure buildup. Braze the suction and
discharge line to the compressor.
G. Connect the electrical plug to the compressor.
The plug is keyed and will only install one way.
(Refer to Figure 5-3)
H. Replace the drier per the instructions in Section
5.9.
I. Evacuate the system per the instructions in Section
5.2
J. Recharge the system per the instructions in
Section 5.3.
K. Replace the insulating tubing on the suction line.
5.5 CONDENSER
The O431 is available with a water-cooled or an air-cooled
condenser. The capacity of the machine is directly related
to keeping the condenser clean and free of debris.
The water-cooled condenser is a tube and shell type. This
condenser requires cool, clean water to function properly.
Inlet and discharge lines must be 3/8” ID minimum.
The air-cooled condenser is a copper tube and alumi-
num
fi n type. The machine must have a minimum of 3”
of clearance on the sides and 6” clearance at the back
for proper air
fl ow.
CONDENSER TESTING
The condenser can be checked for leaks using the bubble
test or using a leak detector.
5.6 EVAPORATOR
The O431 has two freezing cylinder evaporators and a
cab evaporator.
EVAPORATOR TESTING
The evaporator can be checked for leaks using the bubble
test or using a leak detector.
NOTE
Foam insulation in the evaporator will set off elec-
tronic leak detectors if disturbed.
5.7 VALVES
A. THERMOSTATIC EXPANSION VALVE (TXV)
The Thermostatic Expansion Valve (TXV) is used to meter
the refrigerant to the evaporator. It does so by maintain-
ing a low, constant superheat in the evaporator. The
self-regulating TXV is preset by the manufacturer and
adjustment is not recommended. Figure 5-4.
TXV TESTING & ADJUSTMENT
When testing a TXV, run only the evaporator that the TXV
meters. If checking the left side TXV, place the right side
freezing cylinder and cab switches to the OFF position.
If checking the right side TXV, place the left side freezing
cylinder and cab switches in the OFF position. If checking
the cab TXV, place the both freezing cylinder switches in
the OFF position.
NOTE
The bulb has an indent that must be positioned
against the tubing. Good contact between the
bulb and the suction line is necessary for proper
operation of the valve. The bulb must also be well
insulated.
A. Connect a gauge to the Schrader valve on the
suction line next to the evaporator.
B. Connect a thermocouple to the suction line next
to the evaporator.
C. Immediately before the refrigeration cycle ends,
the gauge should read between 19-21 psig.
WARNING
Hazardous voltage
The Main Freezer Power switch must be placed in
the OFF position when disassembling for servicing.
The machine must be disconnected from electrical
supply before removing any access panel. Failure
to disconnect power before servicing could result
in death or serious injury.
Figure 5-4 TXV