Hoshizaki KM-350MWJ Service Manual page 16

1. Sequence and Component Diagnosis
3) Power On: Turn on the power supply, then move the control switch to the "ON"
position and the mode switch to the "ICE" position. A 5-sec. delay occurs. CB red
"POWER OK" LED turns on. If CB yellow "BC OPEN" LED is on (indicating a full
bin), move ice away from BC sensing area.
Note: • CB red "POWER OK" LED remains on unless the 10.5VAC power supply is
interrupted (K2 connector).
• Check CB using the steps in "II.C. Control Board Check" or BC using steps in "II.D.
Bin Control Check and Adjustment."
a) Power On Diagnosis: If CB red "POWER OK" LED is off, confirm 10A fuse is good.
Check for 115VAC at control switch #2 (BK) to neutral (W) then at control switch #1 (P)
to neutral (W). If 115VAC is present on #2 (BK) and not on #1 (P), replace control
switch. If 115VAC is present on control switch #1 (P), check for 115VAC at HPS (P)
to neutral (W) then HPS (BK) to neutral (W). If 115VAC is present at HPS (P) and not
at HPS (BK), HPS is open. See HPS Diagnosis below. If 115VAC is present at HPS
(BK), check for 10.5VAC at CB K2 #1 red wire to CB K2 #2 red wire. If 10.5VAC is not
present, check that the cleaning valve is closed and the interlock switch is closed.
Next, check CT continuity. If open, replace CT.
b) HPS Diagnosis: Check that the condenser coil is not clogged or restricted. Let
refrigeration circuit pressures equalize. If HPS does not reset and pressures are
equalized, replace HPS. If pressures are not equalized, reclaim refrigerant and
diagnose refrigeration circuit restriction. Check that there are no restrictions in the
refrigeration circuit.
Harvest Cycle: HGV, strainer, or check valve.
Freeze Cycle: FM, FMR, TXV, WRV, HM, LLV, strainer, check valve, drier, and
damaged line set or fitting.
Confirm that the location meets installation requirements:
• The appliance is not intended for outdoor use. Normal operating ambient temperature
should be within 45°F to 100°F (7°C to 38°C).
• Allow 6" (15 cm) clearance at rear, sides, and top for proper air circulation and ease of
maintenance and/or service should they be required.
• The appliance should not be located in a corrosive environment.
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, WV remains energized 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.
16