Hoshizaki KM-420MWJ Service Manual page 17

4) 1-Min. Fill Cycle – LED 4 is on. WV energizes. After 1 min., CB checks for a closed
FS. If FS is closed, the harvest cycle begins. If harvest cycle begins (Comp, HGV, FMR
energized), continue to step 5a. If FS is open, fill cycle continues until FS closes (low
water safety protection during initial start up and at the end of each harvest).
Diagnosis: Check that water enters the water tank. If not, check that the water supply
line shut-off valve is open and screens or external filters are clear. Check for 115VAC
at CB K1 #6 (O) to neutral (W). If 115VAC is not present, replace CB. If 115VAC is
present, and WV does not energize, check for 115VAC at WV. If 115VAC is present,
check coil continuity. If open, replace WV. If the water tank fills, but the appliance fails to
start harvest (Comp energized), check for open FS. See "II.E. Float Switch Check and
Cleaning." If FS is closed and CB fails to start the harvest cycle after 1 min., replace
CB.
5a) Initial Harvest Cycle – LEDs 1 and 4 are on. WV continues. Comp, FMR, and 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 3.9 kΩ from the
thermistor and turns harvest termination over to the harvest timer (S4 dip switch 1 & 2
and S5 dip switch 4). WV are energized during harvest for a maximum of 6 min. or the
length of harvest minus HPT setting (S4 dip switch 6), whichever is shorter. See step 5b
below.
a) Comp Diagnosis: Check that evaporator is warming. If not, confirm that Comp
energizes. If not, check for 115VAC at CB K1 #9 (Y) to neutral (W). If 115VAC is not
present, check for 115VAC at CB K1 #10 (BK) to neutral (W). If 115VAC is present
at #10 (BK) and not at #9 (Y), replace CB. If 115VAC is present, check for 115VAC
at mode switch #2 (Y) to neutral and mode switch #1 (V) to neutral. If 115VAC is
present at #2 (Y) and not at #1 (V), confirm mode switch is in "ICE" position. If in
"ICE" position, check mode switch continuity. If open, replace mode switch. If 115VAC
is present at mode switch #1 (V), check for 115VAC at CR solenoid. If 115V AC is
present, confirm contacts are closed. If not, replace CR. If CR contacts are closed,
check Comp external overload, Comp start and run capacitors, Comp start relay, and
Comp motor winding.
b) HGV Diagnosis: If Comp is energized and evaporator is not warming, check that
HGV energizes and opens. Check for 115VAC at CB K1 #2 (P) to neutral (W).
If 115VAC is not present, check for 115VAC at CB K1 #1 (V). If 115VAC is not present,
check wiring for loose connection from CB 10 pin connector pin #1 (V) to mode
switch. If 115VAC is present on #1 (V) and not at #2 (P), replace CB.
If 115VAC is present at #2 (P), check for 115VAC at HGV coil and check HGV coil
continuity. Replace as needed.
c) LLV Diagnosis: Confirm that LLV is de-energized and closed (not bypassing).
If energized, replace CB. If de-energized and bypassing, replace LLV.
d) WRV Diagnosis: Confirm WRV is not leaking by. If WRV is leaking by, confirm HGV
is open and LLV is closed. Next, check for proper refrigerant pressures. If refrigerant
pressures are correct, adjust or replace WRV. See "IV.C. Water Regulating Valve
Adjustment (water-cooled models)."
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