Hoshizaki Sushi Case Troubleshooting

Hoshizaki HNC series sushi cases are designed for temporary display of pre-chilled food products in restaurants, sushi bars, grocery stores and foodservice operations. When these refrigerated display cases experience performance issues, you need a systematic troubleshooting process to quickly identify the root cause and restore proper operation. Follow along belong to handle Hoshizaki sushi case troubleshooting and ensure that units are ready to keep products cool.

This guide covers Hoshizaki HNC-120, HNC-150, HNC-180 and HNC-210 series refrigerated showcases.

Hoshizaki Sushi Case Not Starting

If the showcase fails to power on, start with basic electrical checks before moving into component diagnostics.

Possible Causes

• Ground fault circuit Interrupter is off – If it has tripped or been switched off, the unit will not operate. Try resetting or turning the GFCI back on. 
• Unit is unplugged – Confirm the power cord is securely plugged into the outlet.
• Low supply voltage – Insufficient voltage can prevent startup and lead to compressor issues. Verify the unit is receiving 115V ±10%.
• No power at outlets – Check circuit breakers for tripped or blown fuses. Reset as needed.
• Open electrical circuit or poor connections – Inspect the wiring harnesses and electrical connections. Repair open circuits or replace damaged components.
• Motor protector tripped – The compressor's motor protector may trip due to overheating. Allow the system to cool, then reset the unit. Improve ventilation around the refrigeration system.

Hoshizaki Sushi Case Not Cooling Properly

Poor cooling performance is one of the most common service calls involving refrigerated sushi display cases.

Possible Causes

• Refrigerant leaking – Locate and repair the leak. Evacuate the system and recharge with the correct refrigerant amount specified for the model.
• Condenser fan motor failing – If the condenser fails, head pressure rises and cooling performance drops. Verify fan motor operation and replace as needed.
• Dirty condenser or air filter – Dirty air filters/condensers restrict airflow. Clean the condenser coil and remove any debris. Verify adequate airflow through the condenser section.
• Blocked air intake – Remove any objects blocking the condenser air inlet. Ensure recommended clearances are maintained.
• Unit exposed to direct sunlight – Direct sunlight increases cabinet temperatures and heat load. 
• Located near heat-producing equipment – Installing a sushi case beside grills, ovens, fryers or cooking equipment can overwhelm the refrigeration system.
• Sliding doors open too frequently – Excessive door openings allow warm ambient air to enter the cabinet.
• High ambient temperatures – The unit has a maximum ambient operating temperature of 80°F (27°C). Higher room temperatures may reduce cooling performance.

Frost Build-Up on a Hoshizaki Sushi Case

Frost accumulation may occur on interior or exterior surfaces under certain conditions.

• Exterior frosting – Relative humidity exceeds 60%. Wipe away excess frost with a soft cloth and review the environmental conditions with the operator.
• Interior frosting – Doors are frequently opened or left open for extended periods. Ensure sliding doors close completely after use.