Sequence Of Operation; [A] One Minute Fill Cycle; [B] Initial Harvest Cycle; [C] Freeze Cycle - Hoshizaki KM-61BAH Service Manual

2. SEQUENCE OF OPERATION

The steps in the sequence are as outlined below. When power is supplied, a 5 second
delay occurs at startup. Note that the order of the LEDs from the outer edge of the board
is 5, 6, 8, 4, 7.

[a] ONE MINUTE FILL CYCLE

LED 8 is on. WV opens and the fi ll period begins. After 1 minute, the board checks for
a closed F/S. If F/S is closed, the harvest cycle begins. If not, WV will remain energized
through additional 1 minute cycles until water enters the sump and F/S closes. This
serves as a low water safety to protect the water pump.

[b] INITIAL HARVEST CYCLE

LEDs 5, 6, and 8 are on. WV remains open, Comp energizes, HGV opens, and harvest
begins. As the evaporator warms, the thermistor located on the suction line checks for a
48°F (9°C) temperature. When 48°F (9°C) is reached, a 3.9 kΩ signal turns the harvest
over to the adjustable harvest timer which is factory set for normal conditions. The timer
has settings of 60, 90, 120, and 180 seconds (S1 dip switch 1 & 2). When the harvest
timer completes its count down, the harvest cycle is complete and the freeze cycle
starts. The minimum total time allowed by the board for a complete harvest cycle is 2
minutes. WV is open during harvest for a maximum of 6 minutes or the length of harvest
minus 0, 10, 30, or 50 seconds (adjustable by S1 dip switch 7 & 8), whichever is shorter.
LED 8 goes off when WV closes. PM energizes and runs for the last 0, 10, 30, or 50
seconds of harvest depending on S1 dip switch 7 & 8 setting. LED 7 comes on when
PM energizes. At the end of harvest, the control board checks the position of F/S and
proceeds to the freeze cycle if it is closed or calls for a 1-minute fi ll if it is open.

[c] FREEZE CYCLE

LEDs 5 & 7 are on. Comp continues to run, PM and FMS energize, HGV closes and the
freeze cycle starts. For the fi rst 5 minutes after the thermistor temperature reaches 36°F
(2°C), the control board will not accept a signal from F/S. This minimum freeze period
acts as a short cycle protection. At the end of this period, F/S assumes control. As the
evaporator cools, the thermistor located on the suction line checks the temperature and
PM stops (see "III. 3. TIMING CHART" for details). This is to prevent slushing. As ice
builds on the evaporator the water level in the sump lowers. The freeze continues until
F/S opens and terminates ice production.
9