Hoshizaki FS-1022MLH-C service manual

c. Mechanical Backup Bin Control (MBC) –K8 connector pins #3 and #4 gray (GY) wires: When MBC is closed (calling for ice), 5VDC is present from the white K5 connector pin closest to red K4 connector to the K8 connector pin #3 and #4 gray (GY) wires. Diagnosis: If 5VDC is not present to either pin, CB is bad and must be replaced. If 5VDC is present to pin #3 gray (GY) wire and not to pin #4 gray (GY) wire, MBC is open. See "IV.D.2. Mechanical Backup Bin Control Check."

d. Float Switch (LF/S and UF/S) –K8 connector pin #5 black (BK) wire (common), #6 red (R) wire (upper), and #7 dark blue (DBU) wire (lower): 5VDC is always present from the white K5 connector pin closest to red K4 connector to the

K8 connector pin #5 black (BK) wire (common). 5VDC is present to the K8 connector pin #6 red (R) wire (upper) and pin #7 dark blue (DBU) wire (lower) when the F/S

is open. Diagnosis: If 5VDC is not present at K8 connector pin #5 black (BK) wire, CB is bad and must be replaced. For further F/S diagnostics, see "IV.E. Float Switch Check and Cleaning."

5)Fill "WTRIN" LED is on: The "WTRIN" LED only turns on when the reservoir water level is low enough to open the LF/S. The "WTRIN" LED turns off once the UF/S closes.

24VAC is present at CB K2 connector pin #8 to any light blue (LBU) wire when LF/S is open. Diagnosis: If the LF/S is open and the "WTRIN" LED is off, confirm LF/S status, open or closed. If LF/S is open and "WTRIN" LED is off, CB is bad and should be replaced. If "WTRIN" LED is on and 24VAC is not present from CB connector

K2 connector pin #8 to any light blue (LBU) wire, confirm 24VAC from K2 connector pin #9 to any light blue (LBU) wire. If 24VAC is present on K2 connector pin #9 and not on K2 connector pin #8, CB is bad and must be replaced.

6)Ice Purge Cycle "GM" LED is on: "GM" LED is on, GM and EH energize.

Diagnosis: If "GM" LED is on and GM and EH are off, check for 115VAC from the K1 connector pin #2 white/black (BK) wire to a white (W) neutral wire. If 115VAC is not present, check for 115VAC from CB K1 connector pin #3 brown (BR) wire to a white (W) neutral wire. If 115VAC is present on pin #3 and not on pin #2, CB is bad and should be replaced.

7)Freeze Cycle "GM" and "COMP" LED are on: To bypass the Ice Purge Cycle, press the "SERVICE" button on CB after the "GM" LED turns on. WARNING! Risk of electric shock. Care should be taken not to touch live terminals. When "COMP"

LED is on 115VAC is present at CB X1 relay dark blue (DBU) wire and PDS energizes. Diagnosis: Check for 115VAC from CB X1 relay dark blue (DBU) wire to a white neutral wire. If 115VAC is not present, check X1 relay brown (BR) wire to a white neutral wire. If 115VAC is present on X1 relay brown (BR) wire and not on X1 relay dark blue (DBU) wire, CB is bad and must be replaced.

8)Refill "WTRIN" LED is on: See "5) Fill "WTRIN" LED is on:") above.

Legend: CB–control board; EH–evaporator heater; F/S–float switch; GM–gear motor; GMPR–gear motor protect relay; IS–infrared sensor; LF/S–lower float switch; MBC–mechanical backup bin control; PDS–pump-down solenoid valve; UF/S–upper float switch; WV–inlet water valve

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