Hoshizaki KM-901MWH, KM-901MAH, KM-901MRH/3 service manual

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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