Service Diagnosis; Diagnostic Procedure - Hoshizaki KMD-450MAH Service Manual

IV. Service Diagnosis
1. This unit should be diagnosed and repaired only by qualified service
personnel to reduce the risk of death, electric shock, serious injury, or fire.
2. Risk of electric shock. Use extreme caution and exercise safe electrical
practices.
3. Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.
4. CHOKING HAZARD: Ensure all components, fasteners, and thumbscrews
are securely in place after the unit is serviced. Make sure that none have
fallen into the dispenser unit/storage bin.
5. Make sure all food zones in the icemaker and dispenser unit/storage bin are
clean after the unit is serviced. For cleaning procedures, see "VI. Cleaning
and Maintenance."
A. Diagnostic Procedure
The diagnostic procedure is basically a sequence check which can be used at unit
startup or for system diagnosis. This procedure allows you to diagnose electrical system
and component failures. Before conducting the diagnostic procedure, check for correct
installation, proper voltage per unit nameplate, and adequate water supply. Check CB
using the steps in "IV.B. Control Board Check." Check the dip switch settings to assure
that S1 dip switch 3, 4, 7, 8, 9, & 10 and S2 dip switch 1 through 6 are in the factory
default position. S1 dip switch 1, 2, 5, & 6 are cleaning adjustments and the settings are
flexible. For factory default settings, see "II.C.3.a) Default Dip Switch Settings." As you
go through the procedure, check to assure the components energize and de-energize
correctly. If not, those components and controls are suspect. To check voltages coming
from the board, a diagnostic connector is provided. For details, see "III.B.2. Diagnostic
Connector." To check voltages going to the compressor, a compressor terminal block is
provided. For details, see "III.B.3. Compressor Terminal Block."
1) Turn off the power supply, then access the control box. Clear any ice from BC.
2) Turn on the power supply, then move the control switch to the "ICE" position. A
5-second delay occurs. The "POWER OK" LED on CB comes on. If the "POWER OK"
LED is flashing (indicating a full bin), check BC. See "IV.C.1. Bin Control Check."
1. Risk of electric shock. Use extreme caution and exercise safe electrical
practices.
2. Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.
3) 1-Minute Fill Cycle – LED 8 is on. WV energizes. After 1 minute, CB checks for a
closed F/S. If F/S is closed, the harvest cycle begins. If closed, continue to step 4. If
open, WV remains energized through additional 1-minute fill cycles until water fills the
tank and closes F/S (low water safety). Diagnosis: If WV does not open, check the
supply voltage at WV terminals, check continuity on the coil, confirm the screen or
external filter is not plugged (no water flow). If unit fails to start harvest, check for open
WARNING
WARNING
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