Hoshizaki KM-81BAJ Service Manual page 18

6) Freeze Cycle – LED 5 and 7 is on. Comp and PM continue. FM energizes. HGV
de-energizes. Appliance is held in freeze by a temperature/time short cycle protection
cycle. Thermistor reaches 36°F (2°C), then the 5-min. short cycle protection timer starts.
After the 5-min. short cycle protection timer terminates and FS opens, freeze cycle
terminates.
Slush Control: When slush control is enabled (S2 dip switch 6 "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 (water-cooled models). 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 (P) 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 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 (KM-161B_J) 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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