Hoshizaki KM-501MWH, KM-501MRH, KM-501MAH service manual Sequence of Operation

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B. Sequence of Operation

The steps in the sequence are as outlined below. When power is supplied, a 5 second delay occurs at startup. Note that the order of the LEDs from the outer edge of the board is 1, 4, 3, 2.

1. One Minute Fill Cycle

LED 4 is on. WV opens and the fill period begins. After 1 minute, the board checks for a closed F/S. If F/S is closed, the harvest cycle begins. If not, WV will remain energized through additional 1 minute cycles until water enters the sump and F/S closes. This serves as a low water safety to protect the water pump.

2. Initial Harvest Cycle

LEDs 1, 4, and 2 are on. WV remains open, Comp and FMR energize, HGV opens, and harvest begins. As the evaporator warms, the thermistor located on the suction line checks for a 48°F (9°C) temperature. When 48°F (9°C) is reached, a 3.9 kΩ signal turns the harvest over to the adjustable harvest timer which is factory set for normal conditions. The timer has settings of 60, 90, 120, and 180 seconds (dip switch 1 & 2). The water valve is open during harvest for a maximum of 6 minutes or the length of harvest, whichever is shorter. When the harvest timer completes its count down, the harvest cycle is complete and the freeze cycle starts. The minimum total time allowed by the board for a complete harvest cycle is 2 minutes.

3. Freeze Cycle

LED 1 is on. Comp and FMR continue to run, PM and FMS energize, LLV opens, HGV and WV close and the freeze cycle starts. For the first 5 minutes the control board will not accept a signal from F/S. This 5 minute minimum freeze acts as a short cycle protection. At the end of 5 minutes, F/S assumes control. As ice builds on the evaporator the water level in the sump lowers. The freeze continues until F/S opens and terminates ice production.

4. Pump-Out Cycle

LEDs 1, 3, and 2 are on. Comp and FMR continue to run, HGV opens, LLV closes, and FMS deenergizes. PM stops for 2 seconds and reverses, taking water from the bottom of the sump and forcing pressure against the check valve seat allowing water to go through the check valve and down the drain. At the same time water flows through the small tube to power flush the F/S. When the pump-out timer stops counting, the pump out is complete. Pump out always occurs on the 2nd harvest after startup. Then, depending on the control board setting, pump out occurs every cycle, or every 2nd, 5th or 10th cycle (dip switch 5 & 6).

5. Normal Harvest Cycle

LEDs 1, 4, and 2 are on. Comp and FMR continue to run, HGV remains open and WV opens. As the evaporator warms, the thermistor reaches 48°F (9°C). The control board then receives the thermistor's 3.9 kΩ signal and starts the harvest timer. The water valve is open during harvest for a maximum of 6 minutes or the length of harvest, whichever is shorter. When the harvest timer completes its count down, the harvest cycle is complete and the next freeze cycle starts. The unit continues to cycle through 3, 4 and 5 sequence until the bin control senses ice and shuts the unit down.

Legend: Comp–compressor; FMR–remote fan motor; FMS–self-contained fan motor; F/S–float switch; HGV–hot gas valve; LLV–Liquid Line Valve; PM–pump motor; WV–inlet water valve

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Contents KM-501MAH KM-501MWH KM-501MRH Hoshizaki AMERICA, INC Contents Page KM-501MAH air-cooled Specifications IcemakerWater Cooled Condenser KM-501MWH water-cooledKM-501MRH remote air-cooled URC-6F Condensing UnitSpecifications II. General Information Construction KM-501MWH water-cooled KM-501MRH remote air-cooled Sequence of Operation Cycle Steps Harvest Cycle Freeze Cycle One Minute Control Board Control Board Layout Control Products E Control BoardControl Board Maximum Water Supply Period 6 minutes FeaturesLED Lights and Audible Alarm Safeties Default Dip Switch Settings Controls and AdjustmentsHarvest Timer dip switch 1 Pump-Out Frequency Control dip switch 5 Control Board Replacement Control Board Check ProcedureKM-501MAH air-cooled KM-501MWH water-cooled KM-501MRH remote air-cooled KM-501MAH air-cooled and KM-501MWH water-cooled Wiring DiagramsPsig Timing Chart Page 245 Performance Data488 482 IV. Service Diagnosis Minute KM Diagnostic Procedure No Ice Production Diagnostic ChartsProblem Possible Cause Remedy Problem Possible Cause Remedy Problem Possible Cause Remedy Evaporator is Frozen Up Abnormal Ice Low Ice ProductionOther Problem Possible Cause Remedy Service for Refrigerant Lines Removal and Replacement of ComponentsRefrigerant Recovery Evacuation and Recharge R-404ABrazing Removal and Replacement of CompressorRemoval and Replacement of Drier Removal and Replacement of Hot Gas Valve and Line Valve Removal and Replacement of Expansion ValveRemoval and Replacement of Evaporator Adjustment of Water Regulating Valve Water-Cooled Model Only Adjustment Screw CW Higher CCW Lower Top View Removal and Replacement of Thermistor Removal and Replacement of Inlet Water Valve Removal and Replacement of Fan MotorRemoval and Replacement of Pump Motor Removal and Replacement of Spray Tubes Cleaning and Sanitizing Procedures VI. Cleaning and Maintenance InstructionsCleaning Procedure Sanitizing Procedure Following Cleaning Procedure MaintenanceStainless Steel Exterior Storage Bin and Scoop Preparing the Icemaker for Long StorageAir Filters air-cooled models only Condenser air-cooled and remote air-cooled models only
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KM-501MAH, KM-501MWH, KM-501MRH specifications

The Hoshizaki KM-501MWH, KM-501MAH, and KM-501MRH are standout models in the commercial ice machine market, known for their robust performance and innovative technologies. These machines are specially designed to meet the diverse needs of restaurants, bars, and other food service establishments that require a reliable source of high-quality ice.

One of the defining features of the KM-501 series is their high production capacity. Each model can produce up to 500 pounds of ice per day, ensuring that even the busiest establishments can keep up with demand. The ice produced is crystal-clear, with a unique crescent shape that not only looks appealing but also melts slowly, making it ideal for drinks and food presentations.

The KM-501MWH model is equipped with advanced technology that ensures energy efficiency and reduced water usage. It features a powerful compressor and a highly efficient evaporator, which work together to minimize energy consumption while maximizing output. This makes it an environmentally friendly choice, reducing operational costs for businesses.

The KM-501MAH model stands out with its air-cooled condenser system, which allows for optimal performance without the need for extensive cooling water lines. This makes the installation process easier and reduces complexity, enabling businesses to set up their ice machine with minimal hassle. Furthermore, it features a self-cleaning mode that simplifies maintenance, contributing to consistent ice quality over time.

On the other hand, the KM-501MRH is designed for rugged environments. It is constructed with high-quality materials that enhance durability and longevity, making it suitable for outdoor applications or establishments located in warmer climates. The stainless-steel design not only contributes to the machine's robustness but also ensures easy cleaning and resistance to rust and corrosion.

Another key characteristic of the Hoshizaki KM-501 models is their user-friendly control panel. These machines come with intuitive controls that allow operators to easily adjust settings and monitor performance. This feature is particularly useful for staff in busy kitchens, enabling them to focus on service without constant checks on ice production.

Overall, the Hoshizaki KM-501MWH, KM-501MAH, and KM-501MRH offer excellent performance, energy efficiency, and user-friendliness. Their combination of innovative technologies, durable design, and high output capacity make them exceptional choices for any establishment in need of reliable ice production. Whether for a bustling restaurant or a bar serving up cocktails, these machines deliver ice that consistently meets high standards.
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