Hoshizaki DCM-500BAH-OS, DCM-500BWH-OS service manual IV. Service Diagnosis A. Diagnostic Procedure

IV. Service Diagnosis

A. Diagnostic Procedure

This diagnostic procedure is a sequence check that allows you to diagnose the electrical system and components. Before proceeding, check for correct installation, adequate water supply (minimum of 10 PSIG, maximum of 113 PSIG) and proper voltage per unit nameplate. Always choose a white neutral wire to establish a good neutral connection when checking voltages. LEDs on the control board correspond to the components as they energize.

1)Move the control switch to the "OFF" position, then turn off the power supply. Remove the upper and lower front panels. Confirm the power switch is in the "ON" position and the door switch is engaged.

2)Turn on the power supply, then move the control switch to the "ICE" position. The "POWER" LED is on. The "POWER" LED will not come on if the door switch is not engaged.

3)Fill Cycle – The inlet water valve energizes. The reservoir fills. The lower float switch closes. Nothing occurs at this time. The reservoir continues to fill until the upper float switch closes, energizing the water control relay, which closes the low water safety circuit and de-energizes the inlet water valve. Diagnosis: Check that the inlet water valve fills the reservoir. If not, check for water supply line shut-off valve closed, clogged water filters, clogged inlet water valve screen, power circuit to the inlet water valve (power switch, door switch, power protect relay contacts, transformer, fuses, high pressure switch, bin control, control switch, float switch, water control relay contacts), and the coil on the inlet water valve. Check that the inlet water valve shuts off when the upper float switch closes. If not, check the float switch, water control relay, and inlet water valve.

4)Ice Purge Cycle – "GM" LED is on (60 second short cycle protection). The 60 second timer starts, the gear motor protect relay and gear motor energize. Diagnosis: Check that the gear motor starts. If not, check that the water control relay is energized (inlet water valve should be closed). Check the low water safety circuit on the water control relay (terminals 4 and 6), check for 115/120V at the K1 connector "COM" terminal to neutral and "NO" terminal to neutral on the control board (see wiring diagram), check the gear motor fuse (overload protector), thermal protector, gear motor capacitor, and motor windings. If the gear motor starts, but the auger does not turn, check the gear motor coupling between the auger and the gear motor. If the compressor starts at the same time the gear motor starts, check the X2 compressor relay on the control board.

5)Freeze Cycle – "GM", "COMP" LED are on. The compressor and fan motor energize, the gear motor protect relay, gear motor, and water control relay remain energized. Ice production begins 4 to 6 minutes after the compressor and fan motor start depending on ambient and water temperature conditions. Diagnosis: Check that the compressor and fan motor are running. If not, check for voltage on and to the compressor (X2 relay on the control board). Check that the gear motor protect relay circuit terminals 3 and 5 are closed, check the compressor internal overload (thermal protector), the compressor capacitors, fan capacitor, and voltage to the fan motor.

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