Duke HI

What does Duke HI mean?

On a Duke Product Holding Cabinet, the keypad shows "HI" when the control detects an over-temperature fault: the shelf temperature has stayed higher than the factory preset for about thirty minutes. This happens when power is not removed from the heating element after the shelf reaches its preset. An auxiliary thermostat caps the temperature at 250F to keep it within safe levels.

Symptoms

• The keypad display reads "HI"
• The affected well or shelf runs hotter than its programmed hold temperature
• The heating element stays energized after the shelf reaches set point
• Held product may overheat or dry out

Common causes

• Power is not removed from the heating element once the shelf reaches its preset temperature
• A stuck or failed heater relay leaving the element continuously on
• A faulty temperature control board
• An RTD feedback or sensor reading that under-reports the true shelf temperature

Diagnostic steps

1. 01

   Stop using the affected unit

   The manual states the affected unit should not be used until the cause of the fault is corrected. Move product to a working warmer.

2. 02

   Confirm the displayed fault

   Check the keypad for the "HI" message and note which well or shelf is affected before calling for service.

3. 03

   Run the temperature check procedure

   Using a calibrated digital meter and a thermocouple surface probe, verify shelf temperature per the manual's Temperature Check Procedure and record the readings.

4. 04

   Note your findings for the service line

   Have the displayed fault and measured temperatures ready before calling Duke's troubleshooting hotline at 1-800-735-3853.

5. 05

   Have a qualified technician correct the fault

   There are no user-serviceable parts; a qualified service technician must identify and correct the over-temperature cause before the unit is returned to use.

When to call a professional

Call a qualified service technician whenever "HI" appears. Duke states there are no user-serviceable parts on the Product Holding Cabinet and that the affected unit must not be used until the over-temperature fault is corrected by a qualified technician. An over-temperature condition can damage product and the heating circuit, so contact your Duke authorized service agent or the troubleshooting hotline at 1-800-735-3853 rather than attempting an internal repair yourself.