Delfield Prep Table Error Code Hi: High Temperature Alarm
Hi on a Delfield NP prep table is the high temperature alarm. The display alternates between Hi and the box temperature every 2 seconds. Check the doors, lids and airflow around the unit, and call if the box stays warm.
High: food in the box may be above safe temperature until the condition clears.
- Code
- Hi
- Maker
- Delfield
- Equipment
- Prep tables
- Applies to
- 4400/4500 Series NP refrigerated prep tables with R290 temperature control (4424NP-4472NP, D4424NP-D4472NP, ST4424NP-ST4472NP and variants)
What does Delfield error code Hi mean?
The R290 control compares the box temperature with an alarm point. For refrigerators the factory alarm points are 50F (10C) on the high side and 25F (-4C) on the low side. When the box goes above the high point, the display automatically alternates between Hi and the temperature every 2 seconds. The alarm does not start at once. It sounds and flashes HI 90 minutes after the unit reaches its alarm point, or after any power interruption if the box is still out of range. That delay is meant to allow for door openings and product loading pass without nuisance alarms. When the alarm starts, it sounds for about 10 seconds, stays silent for 50 seconds, and repeats for 15 cycles, then stays silent. The code remains on the display until the condition clears. The manual's cause is simply that the box temperature is above the alarm point.
Affected models and control systems
The manual covers the 4400 and 4500 Series NP refrigerated prep tables with the R290 temperature control, including the 4424NP to 4472NP, D4424NP to D4472NP and ST4424NP to ST4472NP sizes and their variants.
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
- Hi alternating with the temperature every 2 seconds
- Alarm sounding for about 10 seconds each minute
- Food in the pans feeling warm
- Condensation or soft product at the front rail
Possible causes
Listed in Delfield's documentation
- Box temperature above the alarm point, the refrigerator factory high setting being 50F (10C)
Other likely causes — what usually sits behind error code Hi on this control. A technician confirms which one it is before any part is replaced.
- Doors or lids left open or not sealing during a busy service
- Warm product loaded in the box all at once
- Condenser airflow blocked by a wall, boxes or dust, so the unit cannot shed heat
- Power interruption that left the box warm and the compressor still catching up
Safe checks before calling for service
- Close the doors and lids, and check the gaskets for gaps.
- Move warm product out of the box if it was just loaded and let the unit pull down.
- Check that nothing is blocking the vents or the area around the unit, and keep the cabinet away from the wall and hot equipment.
- Watch the display for an hour or two to see if the box temperature is falling.
- For the service call, note the highest temperature you measured, when it started, and any recent power outage.
How a technician diagnoses error code Hi
- Read the code and confirm the actual box temperature with a calibrated thermometer.
- Check door gaskets, hinges and the lid fit.
- Check the condenser for dirt and the fan for operation.
- Check evaporator frost, the defrost cycle and the compressor run time.
- Check sensor readings against the thermometer to confirm the display is accurate.
- Verify the box returns below the alarm point after the repair.
- The R290 refrigerant circuit has to be handled by a trained technician, since the system uses a flammable refrigerant.
- Condenser and fan work needs the unit disconnected and the panels removed.
- Checking sensor readings and defrost behavior against the control's data is service work.
How error code Hi differs from similar codes
Hi is the high alarm. Lo is its low counterpart, which applies to refrigerators and not freezers.
Technical reference
- Document
- Prep Tables & Compact Refrigerators, 4400 & 4500 Series: Specifications, Installation, Operation & Maintenance Manual
- Edition
- Part Number 9295093A, 11/25 (page footers 10/25)
- Models / control
- 4400/4500 Series NP refrigerated prep tables with R290 temperature control (4424NP-4472NP, D4424NP-D4472NP, ST4424NP-ST4472NP and variants)
- Section
- Section 3 Operation, control table p. 24 and 'R290 Temperature Alarm' p. 25
- 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.
Related Delfield prep table error codes
Why did the alarm wait before sounding?
The manual says the alarm sounds and flashes 90 minutes after the unit reaches its alarm point, or after a power interruption if still out of range.
Why did the alarm go silent?
It sounds for 15 cycles of about 10 seconds with 50 seconds of silence between, and then stays silent. The code stays on the display until the condition clears.
What temperature triggers it?
The refrigerator factory alarm point is 50F (10C) on the high side.
Need help with Delfield error code Hi?
A technician confirms the cause on site and gives you the price in writing before any work starts.