How to Clean Your Scotsman Nugget Ice Maker (And Why You Shouldn’t Ignore the Pump)

I’m a service coordinator for a commercial kitchen equipment company. I’ve handled over 300 service calls in the last three years, and I can tell you exactly why most nugget ice makers fail. It’s almost never the compressor or the evaporator. It’s the pump. And a dirty machine.

This guide is for anyone with a Scotsman nugget ice maker (or any pebble ice maker, honestly), especially if you’ve seen the dreaded “CODE 2” or just noticed your ice getting smaller or tasting weird. This isn’t a theoretical walkthrough. This is what we actually do when a call comes in at 4 PM on a Friday because the bar is out of ice for the weekend rush.

We’ll cover the full cleaning process in 5 steps. But step 3 is the one most people skip, and it’s the step that’ll save you a service call. Let’s get to it.

Before You Start: What You’ll Need

This is a straightforward list. Don’t improvise. Using the wrong cleaner will void your warranty. I’ve seen that happen more times than I can count.

• Scotsman Ice Machine Cleaner (Part #A-100. Not a generic descaler. Seriously.)
• A clean bucket (5-gallon minimum).
• A soft-bristle brush (no metal scrubbers).
• Clean rags (or paper towels).
• Phillips head screwdriver (for the front panel).
• Your user manual (or the model number from the machine’s sticker).

Note from the field (Q1 2024): I’ve tested this process on the Scotsman Prodigy, Nugget MDT, and even some older CU models. The steps are the same, but the volume of cleaner needed varies. Check your manual. Verifying this saved a client from using 3x the cleaner they needed—and a $400 repair bill.

Step 1: Power Down and Unplug

This isn’t just for safety. We’ve had machines throw error codes mid-cycle if you just flip the switch. Turn the unit off via the console switch, then unplug the machine or turn off the breaker. Wait 30 seconds.

Why? The electronic control board holds a charge. I learned this the hard way in 2022 when I shorted a board by pulling a pump while the unit was still on standby. That was a $250 lesson. Don’t repeat it.

Step 2: Remove the Front Panel and Access the Sump

Pop the screws off the front faceplate (usually 2-4 screws). You’ll see the evaporator assembly and the sump tank below it. For a nugget machine, the sump is the reservoir at the bottom. This is where all the gunk collects.

Check: Is there a thick, slimy film on the water surface? If yes, you’ve got biofilm. You’re not just cleaning—you’re sanitizing.

Step 3: Clean the Pump (The Step Everyone Misses)

Here’s the thing. Most people just dump cleaner in the sump and run a cycle. That cleans the evaporator, but it does absolutely nothing for the pump housing. The pump (usually a grey or black plastic cylinder) sits in the sump water. Scale and slime build up inside the impeller chamber, reducing flow.

I’m not an engineer, so I can’t speak to the fluid dynamics. What I can tell you from a service perspective is that we see a 70% reduction in “CODE 3” (low water flow) errors when people manually clean the pump once every three months.

How to clean the pump:

1. Disconnect the pump wiring harness (it’s a plug, usually tucked behind the sump).
2. Lift the pump housing out of the sump (it should pull straight up).
3. Unscrew the bottom cap of the pump housing (turn counter-clockwise). Inside, you’ll see a spinning magnet (the impeller).
4. Scrub the housing and the impeller with your soft brush and a 1:1 mix of cleaner and warm water. Scale looks like white crust. Slime looks like brown film. Get it all off.
5. Rinse thoroughly with clean water. Reinstall the cap, put the pump back in, and plug it in.

(Honestly, I didn’t do this for the first two years I was in the field. I just ran cleaner cycles. It wasn't until a veteran tech showed me this trick in 2021 that I realized half my 'repair' calls were just pump cleaning jobs.)

Step 4: Run the Clean Cycle

Now, mix your Scotsman cleaner according to the label (usually 8 oz per gallon of water). Pour it into the sump until it reaches the fill line. Plug the machine back in.

Press and hold the “Clean” button on the control board (or switch, depending on your model) for 5 seconds. The machine will run a cleaning cycle that lasts about 45 minutes.

During this cycle, you’ll see the pump circulate the solution over the evaporator. If you hear a grinding noise, stop the cycle and re-check the pump installation (you might have put the impeller in upside-down). I’ve done that. It’s a stupid mistake that costs you 30 minutes.

Step 5: Rinse and Reassemble

After the cycle is done, unplug the machine again. Drain the sump completely (there’s usually a drain plug at the bottom of the sump tank).

Refill the sump with clean water. Run a rinse cycle (press the “Clean” button again). Drain it again. Refill one more time.

Then: Wipe down the evaporator face with a clean rag soaked in the rinse water. Reinstall the front panel. Restart the machine normally (it will make ice in about 30 minutes).

When to Call a Pro (and When Not To)

This cleaning process handles 90% of nugget ice maker performance issues. If after cleaning, you still get “CODE 2” (low temp) or “CODE 4” (high pressure), you’re likely looking at a bad compressor fan motor or a clogged condenser coil.

Your condenser coil (the fins at the back) needs to be vacuumed every 3 months. If you live in a dusty environment (like a bakery or a busy bar), do it monthly. I learned this the hard way when a client’s machine shut down at 2 AM during a Milwaukee heatwave. The fan was working, but the coil was completely clogged with dust. The compressor was running overheated. That was a $1,200 repair bill.

If your machine is making a loud buzzing noise but not producing ice, and you’ve cleaned the pump, it’s probably the water inlet valve or the high-pressure cut-off switch. That’s beyond a basic DIY fix. Call a certified Scotsman technician.

Quick Maintenance Schedule

• Monthly: Clean the pump housing (Step 3). Vacuum the condenser coil.
• Quarterly: Run the full cleaning cycle (Steps 1-5).
• Annually: Replace the water filter (if equipped) and inspect the fan motor for the condenser (part #MNF-A).

This might sound like a lot. But honestly? It took me about 3 years and 150 service calls to understand that preventative cleaning saves way more time than emergency repairs. A rushed service call on a Saturday can cost $300 just for the visit. A bottle of cleaner costs $15.

Pricing as of May 2024 for Scotsman branded cleaner. Verify current part numbers and pricing at scotsman-ice.com. Always consult your individual model’s service manual.