U-Line Ice Maker SLOW_FLASH: Sensor Problem on the Control Board

SLOW_FLASH at a glance

Code

SLOW_FLASH

Appliance

U-Line ice machine

Applies to

U-Line ice makers with a control board and thermistors

Type

Needs attention soon

Can you clear it yourself?

Sometimes, after the safe checks below

Most likely cause

A thermistor that has failed

What you may notice with SLOW_FLASH

• The control board blinks slowly in a repeating pattern
• Ice output drops off or stops completely
• The unit behaves differently from a normal cycle
• The blink returns after a restart

How the ice machine detects SLOW_FLASH

The control board in your ice maker listens to several thermistors to follow temperature at different points. Each one sends a resistance that the board turns into a reading. The board knows what range of readings makes sense for a working sensor.

If one of the sensors stops sending a sensible value, the board notices and signals the problem with a slow blink, which this unit calls SLOW_FLASH. The signal is general on purpose: it says a sensor has a problem, not which one. A failed thermistor or a loose connector are the causes on the list, and both leave the board without a reading it can trust, so it may limit how the ice cycle runs.

Likely causes of SLOW_FLASH

• A thermistor that has failed
• A loose sensor connector on the control board

Can you keep using the ice machine with SLOW_FLASH?

You may leave the unit on for a while, but expect poor ice production because the board has lost trust in a reading. If you notice water, a hot smell or odd noises, turn it off at the breaker. Otherwise note how it behaves and arrange a check so the failed sensor can be found.

What you can safely check

1. Shut the ice maker down at the breaker or by unplugging it, and turn off the water at the supply valve if that is easy to do.
2. Wait about a minute and restore power.
3. Watch the control board light to see if the slow blink returns during startup.
4. Check for water or damage around the base without opening panels.
5. If the slow blink returns, call us and say how the unit is behaving.

What our technician does for SLOW_FLASH

• Test each thermistor to find the one that has failed
• Check sensor connectors on the control board for a loose fit
• Read the board signal to confirm which sensor is reporting

How to keep SLOW_FLASH from coming back

• Do not pull or crush wiring when moving the unit
• Keep water from reaching sensor connectors by fixing drips quickly
• Protect the ice maker with a surge protector during storms
• Have loose panels reseated gently instead of forcing them shut

Technical reference

Code

SLOW_FLASH

Appliance

U-Line ice machine

Control family

U-Line ice makers with a control board and thermistors

Maker documentation

U-Line owner manuals and support

Checked

November 2026

Code meanings come from the maker’s documentation and our own repair work; we do not reprint the maker’s document. Confirm the full model number before acting on a code. We are an independent repair company, not affiliated with U-Line Corporation.