Manitowoc Ice SL#3 Error Code

What does Manitowoc Ice SL#3 mean?

Safety Limit 3 means that during a freeze cycle the float stayed down (no water sensed) for ten continuous seconds after four minutes of freeze, so the machine stopped. SL#3 is bypassed on the initial cycle; on later cycles it triggers a 30-minute delay during which the control-board SL#1 and SL#2 lights and the Service (wrench) light flash, then the machine auto-restarts.

Symptoms

• Both SL#1 and SL#2 control-board lights flash together with the Service (wrench) light.
• Machine stops about four minutes into the freeze cycle when no water is present.
• Ice machine pauses for a 30-minute delay, then restarts on its own.
• Water trough is empty or the float remains in the down position.
• After many consecutive failures the machine stops and the Service light stays lit.

Common causes

• No incoming water supply (closed shutoff valve or interrupted supply line).
• Water inlet solenoid valve not energizing or stuck closed.
• Float/water-level switch stuck down or failed, so water is never sensed.
• Clogged water inlet, strainer, or supply restriction starving the trough.
• Low or fluctuating water pressure preventing the trough from filling.

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Diagnostic steps

1. Confirm SL#3 from the light pattern

   SL#1 and SL#2 flashing together with the Service (wrench) light indicates Safety Limit 3, a no-water condition. Note the machine self-restarts after a 30-minute delay.

2. Verify the water supply is open

   Check that the building water shutoff and any inline valves to the machine are fully open and that water reaches the inlet. SL#3 is a no-water-sensed fault, so restore supply first.

3. Test the inlet solenoid valve

   Confirm the water inlet solenoid energizes and opens during the fill. Replace the valve if it does not open or remains stuck closed.

4. Inspect the float / water-level switch

   Check that the float moves freely and signals water present. A float stuck down for ten continuous seconds is exactly what triggers SL#3; clean or replace as needed.

5. Clear restrictions and restart

   Clean the inlet strainer and clear any supply restriction, then start a cycle and confirm the trough fills and the float rises so the freeze proceeds normally.

When to call a professional

Call a service technician if water reaches the machine but SL#3 keeps returning after you have verified the supply valve and cleaned the strainer, because testing the inlet solenoid coil, the float circuit, and the control-board water-sensing input safely calls for electrical metering and manufacturer procedures. Persistent shutdowns that exhaust the auto-restart delays and leave the Service light lit point to a component or control fault best handled by a qualified ice-machine technician.