Hoshizaki KM-901MAH Service Manual page 51

3) 1-Minute Fill Cycle – LED 4 is on. WV energizes. After 1 minute, CB checks for a
closed F/S. If F/S is closed, the harvest cycle begins. If closed, continue to step 4. If
open, WV remains energized through additional 1-minute fill cycles until water fills the
tank and closes F/S (low water safety). Diagnosis: If WV does not open, check the
supply voltage at WV terminals, check continuity on the coil, confirm the screen or
external filter is not plugged (no water flow). If unit fails to start harvest, check for open
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 1, 4, and 2 are on. WV remains energized, Comp, FMR,
HGV energize. 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 (S4 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 (S4 dip switch 1 & 2)." When the harvest timer
expires, the harvest cycle is complete. CB checks the position of F/S and proceeds to
the next 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.
"E" CB: WV is energized during harvest for a maximum of 6 minutes or the length of
harvest, whichever is shorter.
"G" CB: WV is energized during harvest for a maximum of 6 minutes or the length
of harvest minus 0 or 50 seconds (harvest pump timer (S4 dip switch 7)),
whichever is shorter. LED 4 goes off when WV de-energizes. LED 3 comes
on and PM energizes and runs for the last 0 or 50 seconds of harvest
depending on S4 dip switch 7 setting. CAUTION! Do not adjust S4 dip
switch 7 out of the factory default position on this model. This dip
switch must be left in the factory default position or this unit will not
operate correctly. For details, see "II.C.3.e) Bin Control Selector/Harvest
Pump Timer (S4 Dip Switch 7)."
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 the freeze cycle is not starting, check the harvest timer adjustment
(S4 dip switch 1 & 2), the thermistor for open circuit, the discharge line temperature,
Comp efficiency, and if HGV is fully open. For a thermistor check, see "IV.E. Thermistor
Check." If 1-minute fill cycle starts after harvest, check that F/S is clean and operating
properly, see "IV.D. Float Switch Check and Cleaning." Make sure PM does not come
on last 50 seconds of harvest. For details, see "II.C.3.e) Bin Control Selector/Harvest
Pump Timer (S4 Dip Switch 7)."
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