Hoshizaki KM-901MAJ Service Manual page 21

f) Refrigerant Pressures, HM, and TXV Diagnosis: If evaporator is still not cooling,
check refrigerant pressures. See "VIII.A. Specification and Performance Data
Sheets."
Next, check HM operation. If refrigeration pressures are above HM setpoint and
HM is bypassing, replace HM. 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.
g) WRV Diagnosis: WRV is factory set and generally no adjustment is required.
If WRV fails to open in freeze, check for proper refrigerant pressures. See "VIII.A.
Specification and Performance Data Sheets." If refrigerant pressures are correct and
WRV does not open, adjust or replace as needed. See "IV.C. Water Regulating Valve
Adjustment (water-cooled models)."
h) Freeze Termination Diagnosis: After 5 min. in freeze, disconnect CB K5 FS
connector. 15 sec. later appliance should switch out of the freeze cycle (15 second
delay after FS opens before terminating the freeze cycle). If appliance remains in
freeze longer than 15 sec. after FS removed, replace CB. If appliance switches with
FS removed but would previously not switch out of freeze with FS connected (long
freeze - 3 beep alarm), see "II.F. Float Switch Check and Cleaning."
Note: Normal freeze cycle will last 20 to 40 min. depending on model and conditions.
Cycle times and pressures should follow performance data provided in this
manual. See "VIII.A. Specification and Performance Data Sheets."
i) Short Freeze Cycle Diagnosis: Confirm water tank fills and overflows during 1 min.
fill and harvest cycles. If not, check water supply filters, shut-off valve, WV screen.
If water tank empties before 5 min. timer terminates and freeze cycle is short, check
that CV is not leaking by (water flowing down the potable drain). If CV is leaking by,
remove and clean CV, replace rubber seat and spring if necessary. If water tank is
full, see "II.F. Float Switch Check and Cleaning." for erratic operating FS.
7) Pump-Out Cycle – LEDs 1, 3, and 2 are on (10/20 second pump-out). Timing of the
first pump-out is determined by S4 dip switch 5. See the table below.
S4 Dip Switch Setting
Comp, FM*, and FMR continue, HGV energize.
Note: If S4 dip switch 3 & 4 are set to 3 off and 4 on, LED 4 turns on and WV and X11
relay energize, energizing X10 relay. NOTICE! S4 dip switch 3 & 4 must not be set
to 3 off and 4 on. Otherwise, PM will rotate in freeze cycle direction instead of
pump-out direction.
Control Board Settings
Pump-Out Frequency
No. 5
OFF Every 10 cycles
ON Every cycle
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Control Board
After 11th freeze cycle
After 2nd freeze cycle