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Error code · Hoshizaki · Ice machines

Hoshizaki Ice Machine 1 Beep: High Evaporator Temperature

One beep on a Hoshizaki KM or KMH ice machine means the evaporator thermistor is reading above 127F (53C), and the machine has shut down. Check for a harvest problem, hot water entering the machine, or a shorted thermistor. A technician should do these checks.

Medium · inspection needed

High: the machine shut itself down on high evaporator temperature and will not make ice until the cause is cleared.

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Code
1 beep
Maker
Hoshizaki
Equipment
Ice machines
Applies to
KM / KMD / KML / KMS crescent cubers, "E", "G" and "J" control boards (KM-1301 to KM-2600, KMD-460/530, KML-250 to 631, KMS-822)

What does Hoshizaki error code 1 beep mean?

The evaporator thermistor measures the temperature of the evaporator plate. During harvest, hot gas warms the plate briefly to release the ice. If the thermistor reads above 127F (53C), the control treats it as an unsafe condition and shuts the machine down with one beep. The manual names three causes: a stuck hot gas valve (HGV) or relay, hot water entering the icemaker, and a shorted thermistor. A hot gas valve that stays open keeps feeding heat to the evaporator long after harvest should end. Hot water entering the machine, from a wrong supply or a bad connection, does the same. A shorted thermistor reads a false high value, so the machine can shut down with a cold evaporator. Telling these apart takes measurement, since the readings look alike. Do not restart the machine repeatedly, because the cause stays in place.

Affected models and control systems

KM-1301SAH/3 through KM-2500 and KMH-2000 stackable cubers with E and G control boards; the same table appears in the manual for the KMD-460/530 and KML-250 to 631 G-board models.

Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.

What you may notice

  • One beep alarm
  • Machine shut down
  • Evaporator that feels hot or ice that melts on the plate
  • Water supply that seems warm

Possible causes

Listed in Hoshizaki's documentation

  • Stuck HGV or relay
  • Hot water entering the icemaker
  • Shorted thermistor

Other likely causes — what usually sits behind error code 1 beep on this control. A technician confirms which one it is before any part is replaced.

  • A hot water line cross-connected to the ice machine supply
  • A hot gas valve with debris that holds it open
  • A thermistor lead rubbed against a metal edge until it shorts

Safe checks before calling for service

✓ What an operator can do
  1. Check that the water supply line is cold and connected to the right supply.
  2. Switch the machine off and avoid restarting it repeatedly.
  3. Do not open panels or handle the evaporator while it is hot.
  4. Write down the model, when the beep started and whether the water supply was recently changed.

How a technician diagnoses error code 1 beep

  1. Read the alarm and confirm the control board generation, E or G.
  2. Check supply water temperature at the machine.
  3. Check the hot gas valve and its relay for sticking.
  4. Measure the evaporator thermistor resistance at a known temperature.
  5. Replace the failed part only after the test and confirm a normal harvest.
! Leave this to a technician
  • Hot gas valve and relay checks involve live circuits and refrigerant lines.
  • A hot evaporator and hot gas are a burn risk.
  • A thermistor shorted to ground and a real overheat look the same without a meter.

How error code 1 beep differs from similar codes

These beep codes are verified on the E and G control boards listed here; other board generations may differ and are not covered on this page.

Technical reference

Maker documentation
Hoshizaki owner support
Edition
Number 73208, issued 7-7-2015, revised 8-11-2015
Models / control
KM / KMD / KML / KMS crescent cubers, "E", "G" and "J" control boards (KM-1301 to KM-2600, KMD-460/530, KML-250 to 631, KMS-822)
Section
III.B. LED Lights and Audible Alarm Safeties, pp. 49-50
Checked
October 2026

We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.

→Same maker

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1 beepQuestions about Hoshizaki error code 1 beep
Why did the machine shut down?

The evaporator thermistor read above 127F (53C), which the control treats as unsafe.

Can I restart it?

You can try once, but if the cause is a stuck valve or hot water supply it will repeat.

Is a shorted thermistor possible?

Yes, the manual lists it as one of three causes.

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