Hoshizaki KM-301BAJ Service Manual page 17

Slush Control: When slush control is enabled (S2 dip switch 5 "ON"), PM de-energizes
when thermistor reaches 50°F (10°C) (3.9kΩ) for 10 sec. then, energizes for 50 sec.
repeatedly. When thermistor reaches 34°F (1°C) (5.9kΩ) PM de-energizes for 10 sec.,
energizes for 50 sec., de-energizes for 10 sec., again, then energizes the remainder of
the freeze cycle.
a) Freeze Cycle Diagnosis: Confirm Comp and PM continue. Confirm that FM
energizes. Confirm WRV opens. Next, confirm HGV de-energizes. During the first
5 min. of freeze, confirm evaporator is cooling. If not, confirm WV de-energized (not
leaking by), HGV de-energized (not bypassing), FM energizes, TXV operates correctly,
WRV opens, Comp is efficient, and refrigerant charge is correct.
See "VIII.A. Specification and Performance Data Sheets."
b) Comp Diagnosis: If Comp de-energizes once freeze begins, check that appliance has
not shut off on HPS (CB "POWER OK" LED off). If so, check "3)b) HPS Diagnosis"
above. If CB "POWER OK" LED is on, check for 115VAC at CB K3 #2 (V) to neutral
(W). If 115VAC is not present and LED 5 is on, replace CB. If 115VAC is present, check
for 115VAC at CR coil. If 115VAC is present, check CR coil and contact continuity.
Replace as needed. If CR is okay, check Comp start relay and start capacitor. Next,
check Comp motor winding continuity. If Comp is energized but evaporator is not
cooling, check for an inefficient Comp. See "VIII.A. Specification and Performance
Data Sheets."
c) WV and HGV Diagnosis: If WV is energized, check for 115VAC at CB K5 #4 (O) to
neutral (W). If 115VAC is present after PM energizes in harvest cycle, replace CB.
If 115VAC is not present, replace WV (bypassing). If HGV did not de-energize at the
end of harvest, check for 115VAC at CB K5 #2 (V) to neutral (W). If 115VAC is present
and LED 6 is off, replace CB. If 115VAC is not present, replace HGV (bypassing).
d) PM Diagnosis: Confirm water is flowing over evaporator from PM and not WV. If PM
de-energizes once freeze begins, check for 115VAC at CB K5 #3 (DBU) to neutral (W).
If 115VAC is not present, replace CB. If 115VAC is present and PM is de-energized,
check for 115VAC at control switch #4 (DBU) to neutral (W). If 115VAC is present at
CB K5 #3 (DBU) and not at control switch #4 (DBU), check control switch continuity
between #5 (BK) and #4 (DBU). Replace as needed. If 115VAC is present at control
switch #4 (DBU) to neutral (W), check PM capacitor and motor winding continuity.
e) FM Diagnosis: If FM does not energize, check for 115VAC at CB K5 #1 (BK) to
neutral (W). If 115VAC is not present, replace CB. If 115VAC is present:
For FM, check capacitor, motor winding, and blade for binding.
f) Refrigerant Pressures and TXV Diagnosis: If evaporator is still not cooling, check
refrigerant pressures. See "VIII.A. Specification and Performance Data Sheets."
Next, check TXV for proper operation. Remove TXV bulb and hold it in your hand,
refrigerant low-side pressure should rise, place TXV bulb in ice water, refrigerant
low-side pressure should drop. A 10 to 15 pound pressure swing between warm and
cold conditions indicate a good TXV. If a 10 to 15 pound swing is not present, replace
TXV.
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