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

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.