Hoshizaki KMD-270AWA Service Manual page 31

a. Lower Float Switch 1st Activation: Refill – The refill can occur at any time during the
freeze cycle (1 refill per cycle). As ice builds the water level drops in the reservoir and the
lower float switch activates (opens). LED 5 comes on and the control board energizes the
fill water valve. The fill water valve remains energized until the upper float switch closes or
the 1 minute fill timer terminates, whichever comes first.
b. Lower Float Switch 2nd Activation: The unit is held in freeze by a 5 minute short cycle
protection timer which starts after the thermistor temperature reaches 2°C. After the 1st
lower float switch activation and refill, ice continues to form and the water level drops in
the reservoir. When the lower float switch activates (opens) a second time, the freeze
cycle terminates (freeze can only be terminated on the second activation of the lower float
switch and after the minimum freeze period). Diagnosis: During the minimum freeze
period, confirm that the evaporator temperature drops, compressor, fan motors and pump
motor are energized and that the hot gas valves, harvest water valve and fill water valve
(except during refill) are de-energized and not bypassing. Make sure the expansion
valves are operating properly and, in cold conditions. Make sure that the drain water valve
is not leaking by (water flowing down the potable drain). Check for proper unit pressures,
or an inoperative compressor. Disconnect the 3-pin float switch connector from the control
box. 15 seconds after disconnecting the 3-pin float switch connector, LED 5 comes on
and refill begins. Connect the 3-pin float switch connector back on the control box. When
the refill is finished (LED 5 goes off), disconnect the 3-pin float switch connector again. If 5
or more minutes have elapsed in the freeze cycle, the unit should switch out of the freeze
cycle. After the unit switches out of freeze, reconnect the 3-pin float switch connector to
the control box. If the unit remains in freeze with the float switch disconnected, replace the
board. To check the float switch, see "II. 5. [c] FLOAT SWITCH CHECK PROCEDURE."
Note: Normal freeze cycle will last 20 to 40 minutes depending on model and conditions.
Cycle times and pressures should follow performance data provided in this manual.
6) Drain Cycle – The compressor remains energized, the hot gas valve energizes, the fan
motor de-energizes. The drain valve and pump motor energize, allowing water to drain
from the tank for 20 seconds. This removes contaminants from the water tank.
Diagnosis: If the drain valve does not open, check the circuit. Check for proper voltage. If
water does not drain out, check and clean the tubing at the drain valve and then check
and clean the valve assembly.
7) Normal Harvest Cycle – same as the initial harvest cycle – Return to step 4.
Note: Unit continues to cycle until bin control is satisfied or power is turned off. (The drain
cycle can be adjusted to occur every cycle, or every 2, 5, or 10 cycles. The factory
default is every 10 cycles.) The unit always restarts at the 1 minute fill cycle.
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