Hoshizaki KMD-450MAH Service Manual page 33

F/S or bad 1-minute timer in CB. See "IV.D. Float Switch Check and Cleaning" and "IV.
B. Control Board Check."
4) Initial Harvest Cycle – LEDs 5, 6, and 8 are on. WV remains energized, the contactor
coil energizes to energize Comp and FMR, and HGV energizes. CB monitors the
warming of the evaporator via the thermistor located on the suction line. When the
thermistor reaches 48°F (9°C), CB reads a 3.9 kΩ signal from the thermistor and turns
harvest termination over to the harvest timer (S1 dip switch 1 & 2). The harvest timer
has settings of 60, 90, 120, and 180 seconds. For details, see "II.C.3.b) Harvest Timer
(S1 dip switch 1 & 2)." WV is energized during harvest for a maximum of 6 minutes
or the length of harvest minus 0, 10, 30, or 50 seconds (harvest pump timer (S1 dip
switch 7 & 8)), whichever is shorter. For details, see "II.C.3.e) Harvest Pump Timer
(S1 dip switch 7 & 8)." LED 8 goes off when WV de-energizes. LED 7 comes on and
PM energizes and runs for the last 0, 10, 30, or 50 seconds of harvest depending on
the harvest pump timer setting. This circulates water over the evaporator for the last
0, 10, 30, or 50 seconds of harvest. When the harvest timer expires, the harvest cycle
is complete. CB checks the position of F/S and proceeds to the freeze cycle if it is
closed or calls for a 1-minute fill cycle if it is open. The minimum total time allowed by
CB for a complete harvest cycle is 2 minutes. Diagnosis: Check if Comp is running,
HGV and WV still energized. Average harvest cycle at factory setting is 2 to 3 minutes.
How long does initial harvest last? 1.5 minutes after initial harvest begins, touch Comp
discharge line. Is it hot? If not, check refrigerant pressures and Comp operation. If it is
hot, touch the inlet line to the evaporator. Is it hot? If it is hot and PM does not run per
the harvest timer setting and/or the freeze cycle does not start, check the harvest timer,
the thermistor for open circuit, the discharge line temperature, PM circuit and capacitor,
PM terminal on the diagnostic connector (violet wire) for voltage, Comp efficiency,
and if HGV is fully open. For a thermistor check (including harvest timer check), see
"IV.E. Thermistor Check." For diagnostic connector details, see "III.B.2. Diagnostic
Connector."
5) Freeze Cycle – LEDs 5 and 7 are on. Comp and FMR remain energized, PM, LLV,
and FM energize. WV and HGV de-energize. CB monitors the cooling of the evaporator
via the thermistor located on the suction line. When the thermistor drops to 36°F (2°C),
CB reads a 5.5 kΩ signal from the thermistor and starts a 5-minute short cycle
protection timer. After the 5-minute short cycle protection timer expires, CB turns freeze
termination over to F/S.
The float switch selector (S2 dip switch 2) and the refill counter (S2 dip switch 3 & 4)
allow certain models to use a double F/S to refill the water tank during the freeze cycle.
The KMD-450MAH and KMD-450MWH use a single F/S and do not refill. For details,
see "II.C.3.h) Float Switch Selector (S2 dip switch 2)" and "II.C.3.i) Refill Counter (S2
dip switch 3 & 4)." CAUTION! Do not adjust S2 dip switch 2, 3, or 4 out of the
factory default position on this model. These dip switches must be left in the
factory default position or this unit will not operate correctly.
The anti-slush control (S2 dip switch 6) helps prevent slushing during the freeze
cycle on certain models. When activated, the control board monitors the cooling of
the evaporator via the thermistor located on the suction line. When the thermistor
drops to 34°F (1°C), the control board reads a 5.8 kΩ signal from the thermistor
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