Hoshizaki REFRIGERATED PREP TABLE WITH RAISED RAIL 73168 User Manual

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5. Defrost Thermistor (cabinet) Malfunction Alarm (E8)

If the control board detects an open defrost thermistor, "E8" is displayed. When the
control board detects a shorted defrost thermistor, a 10-minute delay timer begins. After
the 10‑minute delay timer expires, "E8" is displayed. To bypass the 10‑minute delay
timer, move the power switch to the "OFF" position. Then, while pressing the rail "SET"
button, move the power switch to the "ON" position.
• If this alarm appears, first make sure that the thermistor is properly connected to the

control board.

• A shorted defrost thermistor is not detected by the control board during the 1st hour

after power is turned on. To bypass the 1-hour delay timer, move the power switch to
the "OFF" position. Then, while pressing the rail "SET" button, move the power switch
to the "ON" position.

Reset Options
The alarm automatically resets when one of the following conditions is met:
• The defrost thermistor is secured to the control board.
• The defrost thermistor is within normal operating range. For details, see "II.E. Thermistor

Check."

• A functioning defrost thermistor is installed.

Possible Causes
• Trouble with the defrost thermistor. For checkout procedure, see "II.E. Thermistor Check."
• Trouble with the control board reading the defrost thermistor.

E8 Alarm (short circuit) Reset

Under 10 min.

E8 (short circuit )
Detection Point
122°F (50°C)

Temperature
Display

E8
Blinking

E8 Alarm
(open circuit)
Reset

E8 Alarm Timer Start

E8 Alarm
Timer Start

Temperature Display

E8 Alarm (open circuit)
Detection Point
-67°F (-55°C)

E8
Blinking

10 min.

E8
Alarm

5a. Secondary Defrost Thermistor (Rail, not used)

The secondary defrost thermistor (located behind the wire cover) is not used for
operation of the unit. It is used for control board programming and should not be
removed. An "E8" alarm occurs when the secondary defrost thermistor is removed or
fails. For details, see "III.A.6. Defrost Thermistor (cabinet) Malfunction Alarm (E8)."