Temperature sensor
Common error-code part. Confirm resistance and connector style.
Hoshizaki F2 Error Code — What It Means
F2 on a Hoshizaki ice machine indicates an ice full sensor fault — the machine has detected that the ice storage bin is full and has stopped production, or the ice full sensor has developed a fault condition that prevents the machine from operating normally. Hoshizaki uses a mechanical bin thermostat or a photocell bin control depending on the model. On models with a digital control board (IM, KML, KMD series with electronic controls), F2 specifically indicates that the bin full signal has been received continuously for longer than expected, suggesting a stuck sensor rather than a genuinely full bin.
Common Causes
- Ice bridging over the bin sensor — A clump of ice extending from the evaporator to the bin thermostat probe can hold the thermostat in the “bin full” position even after harvested ice has dropped into the bin properly.
- Bin thermostat or photocell failure — The mechanical bin thermostat can fail in the open (bin full) position, permanently preventing ice production. A photocell sensor can become obstructed with scale or mold growth.
- Evaporator ice sheet not releasing cleanly — If ice sheets are not fully releasing from the evaporator, they can drape over or contact the bin thermostat, falsely signaling full.
- Scale or biofilm on the photocell sensor — On KML series machines with photocell bin controls, mineral scale or biological growth on the lens face blocks the light path, triggering a false F2.
Step-by-Step Fix
- Clear the bin and inspect the sensor — Remove all ice from the bin. With the bin empty, observe whether the machine restarts. If it does not, the sensor is stuck or failed.
- Locate the bin control (thermostat or photocell) — The bin thermostat probe is typically clipped to the ice chute or the evaporator discharge area. The photocell sensor is mounted in the ice drop zone.
- Test the bin thermostat — At room temperature, the thermostat contacts should be closed (continuity). If they read open at room temperature, the thermostat has failed and must be replaced.
- Clean the photocell sensor (if applicable) — Clean the sensor lens face with a soft cloth and a food-safe sanitizer. Remove any scale with a citric acid solution.
- Check for ice bridging — Inspect the evaporator discharge area for ice that has bridged between the evaporator and the sensor. Break up and remove any ice bridges.
- Run a manual harvest cycle — Initiate a manual harvest to confirm ice sheets are releasing cleanly and dropping fully into the bin.
- Reset and verify — After cleaning or replacing the sensor, restore power and confirm the machine completes a full ice-making and harvest cycle without triggering F2.
Parts Often Needed
| Part | Notes |
|---|---|
| Bin thermostat | Hoshizaki OEM; match the specific KML or IM model |
| Photocell bin control | Match model series; includes transmitter and receiver on some models |
Technician Tips
When diagnosing commercial refrigeration faults, start with the controller’s alarm history. Most digital controllers (Dixell, Carel, Eliwell) store the last 5-10 alarms with timestamps. An E1 alarm that appears consistently every few hours suggests a sensor going bad — the resistance value drifts until it’s out of range. An intermittent HI/LO alarm that appears only during hot afternoons suggests a condenser issue, not a sensor fault.
Prevention: Schedule quarterly condenser coil cleaning. Dirty coils are the #1 cause of high-head-pressure faults and compressor overheating in commercial refrigeration. Use a soft brush and compressed air — never a pressure washer on the coil fins.
Need Replacement Parts?
Before ordering, match the ice-machine part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
If F2 persists after cleaning and sensor replacement, a technician should inspect the harvest cycle — a refrigerant or harvest valve issue can prevent clean ice release, causing recurring bin sensor false trips.