Vogt P18AL TUBE-ICE, Service Manual

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P18AL Service Manual
TROUBLESHOOTING
3/6/07
8-3
Symptom: Freeze-up due to extended freeze period
Possible Cause Possible Remedy
Freeze timer (T2) set to long Adjust timer or replace if defective. See FIGURE 9-2.
Freezer pressure switch (FPS) set too low or defective
(optional) Adjust switch or replace if defective.
Water tank drain valve, make-up water float valve or flushing
valve stuck or opened Close, repair, or replace valve as needed. The float valve
should be adjusted low enough that water should not run out
the tank overflow during the freeze cycle.
Thaw gas solenoid valve (18) leaking through during freeze Check the manual opening stem to make sure it is in the
automatic position (stem screwed in). Check for leakage by
sound, temperature difference and frost during the freeze
cycle. Leakage should stop by closing the hand stop valve
downstream of thaw gas valve. Isolate and repair or replace
the valve as needed.
Compressor running unloaded If the compressor is running unloaded, the motor amp draw
will only be 60%-70% of the normal amp draw of a loaded
compressor.
Refer to the compressor manual for normal oil pressure needed
to load the compressor cylinders and any further procedures to
check the mechanical function of the unloader mechanism.
Symptom: Freeze-up due to ice failing to discharge
Possible Cause Possible Remedy
Freeze timer (T2) set to long Adjust timer or replace if defective. See FIGURE 9-2.
Extended freeze period (if freezer pressure switch is used) Check freezer pressure switch adjustment. See FIGURE 9-1
for adjustment and TABLE 7-2 for average hole size. Make
sure all water distributors are in place (one in each tube).
Thaw time too short (T) Adjust thaw timer (T) to allow all ice to clear the cutter and ice
discharge opening with at least 30 seconds to spare. Replace
defective timer. See pressure regulating valve adjustment.
Thaw pressure to low The thaw gas regulator should be adjusted to increase the
pressure in the freezer to 60-65 psi during a harvest. Isolate
and repair or replace the valve as needed.
Insufficient heat for thawing due to low condensing pressure The head pressure should be maintained form 175-190 psi
(maximum 200) usually by a water regulating valve or fan
cycling switch. Check to make sure these controls are working
properly. Cold prevailing wind can also be a factor.
Insufficient heat due to non-condensables (usually air) in the
system If non-condensables are present with the refrigerant, the
saturated temperature will not relate to the pressure reading at
the receiver and the refrigerant will be cooler, although
pressure will be high. Air can be purged from the system by
following the procedure in the Section 9, “Purging Non-
Condensables”.
Insufficient heat due to low refrigerant charge The refrigerant level in the receiver should be near the
operating mark at the end of a freezing cycle to provide
enough volume of warm gas for harvesting. DO NOT
OVERFILL RECEIVER. See Table 3-2
Cutter or cutter disc does not turn Check cutter gear reducer and drive gear for proper operation
and alignment. Check for broken gear teeth or sheared shaft
key. Replace defective parts.
Compressor not running unloaded during thaw cycle.
(for dedicated high side only) Check compressor motor Amp draw. During the thaw cycle,
the compressor motor Amp draw should be 60 - 70% of
normal amp draw during the freeze cycle. Check compressor
unloader solenoid coil to make sure it is energized and the
valve is opening during the thaw cycle.