This video will demonstrate the proper way to perform a system diagnosis on flaker ice maker units. Before we cover how to diagnose electrical and component failures, let's review the flaker's sequence of operation. The sequence of operation is controlled by a series of timers within the solid state timer board. First, the flaker begins a startup when the flush switch is set to the ice position and the power switch is set to the on position. Power is then supplied to the inlet valve, allowing water to fill the reservoir. The unit will not begin the ice making process until the reservoir is filled. Next, when the dual float switches indicate a full reservoir, the bin control takes over and allows the unit to sequence up. At this point, the gear motor and condenser fans start. Should the gear motor experience undue stress from the rotating auger or the pressure of ice extrusion, the machine will automatically shut down through the gear motor protect relay, saving wear on the gear motor and bearings. After one minute, the compressor starts. This delay allows any ice left in the evaporator cylinder to be removed before basic refrigeration begins. As the refrigeration cools the water in the evaporator, ice begins to form on the cylinder wall within two to three minutes. The gear motor turns an auger inside the stainless steel cylinder. As ice forms on the inside wall, the auger breaks away the ice and moves it upward. The upward pressure extrudes the ice out the top of the cylinder and into the bin. Ice production will continue until the bin is full. Once the bin is full, the ice pushes against the bin control paddle. The paddle operates a magnetic proximity switch and a shutdown process begins. Within six seconds after the bin control indicates a full bin of ice, the gear motor, compressor, and fan stop. Self-contained units and DCMs sequence down. One minute after the bin control opens and indicates a full bin of ice, the compressor stops. One minute later, the gear motor and fan stop. Before beginning the diagnostics on a flaker ice maker, it's important that you first make sure there is proper water and power supplied to the unit. When troubleshooting for system failures, first remove the covers of the unit. Place the flush switch to the ice making position and turn the machine on. Remember, the unit will not start up unless the reservoir is full and both float switches are closed. If the water valve does not energize, check the water valve terminals for voltage. A meter reading of 24 volts indicates that the water control relay circuit is supplying power to the water valve. This means that the problem is either the water valve coil is open, the valve is stuck closed, or the water valve screen is plugged with debris. At this point, turn off the power supply and shut off the water supply. Remove the thumb nut and check for debris plugging the inlet stream. Next, check the coil for continuity with an alm meter. Replace the water valve if it is defective. Some flaker models have a built in periodic flush. The flush valve is operated either by the manual flush switch or by the 12 hour flush timer. If no power is supplied to the water control circuit at start up, it could be off on the 12 hour timer. You can advance the timer or check the timer contacts with the volt meter to determine if this is the case. After checking the flush timer, if there is no power to the inlet water valve, check the controls transformer secondary to make sure control voltage is present. You can easily check the secondary and circuit fuse by removing the control box cover and checking across terminals one and two on the timer for 24 volts. If control voltage is present, check the flush ice switch for contacts. If the water valve is energized and the reservoir is over flowing, check both float switches and the water control relay. To check the float switch, twist and lift the assembly out of the reservoir. The float switch has three wires: black, red, and blue. First, check the blue and black or common wire with your meter at the control box connector. When you raise the bottom float, the switch should be closed. When it is down, the switch should be open. Now, check the red and black wires. The float switch should again be closed when the top float is up and open when it is down. If the float switch needs to be cleaned, soak it in ice machine cleaner. If you take it apart, mark the top of the floats and be sure to replace them in their original position. This will allow you to have the correct timing on the water control relay circuit. To check the water control relay, review the wire color code on the wiring diagram and check the relay with your meter. When the reservoir fills and the water valve stops, the gear motor and condenser fan should start. If this does not occur, locate the bin control terminals on the timer board. Check the bin control's proximity switch by disconnecting the wires from these terminals. Check the wires with an alm meter to assure that the bin control is closed. Another way to check the proximity switch is to use a jumper. If you jumper across the bin control circuit pins five and six and the machine starts up, the bin control proximity switch is your likely problem. The terminal numbers may vary on older models. Always verify the terminal numbers on the unit wiring diagram. The solid state timer board controls the entire sequence of operation. To diagnose a bad timer board, first check across terminals one and two. You should have 24 volts or the machine will not cycle up. Then, jumper across terminals three and four. If the machine starts up, you should check your water control relay circuit as previously discussed. If the machine still doesn't start, other circuits must be checked before condemning the timer board. Now, jumper across terminals five and six to check the bin control. If the unit cycles up with the jumper in place, the board is good and the problem is with the bin control circuit. Check your wiring diagram to determine which voltage should be present at terminal eight. Depending on the model you are working on, this terminal could either be a line voltage or a controlled voltage circuit. If your meter reads the proper voltage, then the timer board is good and is supplying power to the gear motor relay or circuit. If the gear motor relay is not energizing at this point, it may have a bad coil or a mechanical problem. If the condenser fan is running and the gear motor is not, the relay is operating properly and there may be a problem with the gear motor circuit. If the gear motor and fan start but the compressor does not, check the gear motor protect relay. To check this circuit, jumper across terminals ten and eleven. If the compressor starts up within one minute, the problem is in the gear motor protect relay. If the compressor doesn't start after jumping ten and eleven, check the compressor circuit. To perform a quick check of the compressor circuit, turn the power switch off. Place a jumper across the black compressor relay on the timer board. This will bypass the timer and allow the compressor to start. Turn the power back on. If the compressor runs, the compressor circuit is okay. If not, use basic diagnostic procedures to check the compressor and start components. If the compressor circuit is okay, the timer board is probably bad and will need to be replaced. Remember, when servicing any Hoshizaki ice maker, always refer to your tech spec's guide for detailed information or call the Hoshizaki service hotline on your screen. Now that you have learned the various check out procedures, you should be able to diagnose most problems that occur with the flaker.
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Easily diagnose issues with your Hoshizaki ice machine with these step-by-step procedures.
Hoshizaki is an industry leader in manufacturing commercial ice machines. They offer a variety of ice shapes to suit any site application. From cube ice to chewable ice and even flaked ice, Hoshizaki has options for every sector of food service.
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