Sequence Of Operation; [A] One Minute Fill Cycle; [B] Initial Harvest Cycle; [C] Freeze Cycle - Hoshizaki KMD-410MWH 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,
9, 4, 7.

[a] ONE MINUTE FILL CYCLE

LED 8 is on. HWV opens and the fill period begins. After 1 minute, the board checks for a
closed LF/S. If LF/S is closed, the harvest cycle begins. If not, HWV will remain energized
through additional 1 minute cycles until water enters the sump and LF/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. HWV remains open, Comp energizes, HGV opens, and harvest
begins. As the evaporator warms, the thermistor located on the suction line checks for a 9°C
temperature. When 9°C is reached, a 3.9 k 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.
HWV 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 HWV 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 LF/S and proceeds to the freeze cycle if
it is closed or calls for a 1-minute fill 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 first 5 minutes after the thermistor temperature reaches 2°C, the
control board will not accept a signal from LF/S and UF/S. This minimum freeze period acts
as a short cycle protection. At the end of this period, LF/S and UF/S assumes control. As ice
builds on the evaporator the water level in the sump lowers and LF/S opens, FWV opens
(LED 9 is on when FWV is open). The refill will last until UF/S closes or for 60 seconds,
whichever is shorter. After UF/S closes, FWV closes 3 seconds later. KMD-410 refills 1 time.
After the refill, the freeze continues until LF/S opens again and terminates ice production.

[d] DRAIN CYCLE

LEDs 4, 5, 6, and 7 are on. Comp continues to run, HGV opens, FMS de-energizes. PM
stops for 2 seconds, DV energizes, then restarts to take water from the sump and force it
through DV and down the drain. When the drain timer stops counting, the drain is complete.
The drain timer is 10 or 20 seconds (S1 dip switch 3 & 4). Drain cycle always occurs on the
2nd harvest after startup. Then, depending on the control board setting, drain cycle occurs
every cycle, or every 2nd, 5th, or 10th cycles (S1 dip switch 5 & 6).
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