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  • Scotsman CU50 drain pump keeps running. Never shuts off

    Posted by Steve Liskey on June 24, 2024 at 10:12 pm

    CU50 Scotsman ice maker water pump will not stop running. I suspect the controller board. Any thing else this might be? Have had the board replaced once for the same reason. What could be destroying these boards?

    fixbear replied 2 weeks, 5 days ago 3 Members · 2 Replies
  • 2 Replies
  • Tito

    June 28, 2024 at 9:48 am

    Did you check the pressure switch on the drain pump? Is the drain line kinked or restricted with biofilm or mold? Also, is the water inlet valve not closing all the way and allowing constant water flow, or is the water pressure above 80 psig?

  • fixbear

    June 30, 2024 at 10:45 pm

    Your title say’s the drain pump, but I’m not certain that’s what you are referring to as you stated the control board solved it the first time. And the control board has no connection to the drain pump. It is totally independent to the rest of the machine electrically. And can only be shut off by unplugging the machine. It is wired directly to the supply lines and is controlled by a membrane pressure switch directly in front of the pump on the left. It has a small tube that connects to the “U” shaped drain tube. Likely the tube is plugged or the membrane switch. They do get fungus and bacterial deposits as well as minerals in them. Proper cleaning cycles with Scotsman cleaner is a must. Although these domestic models like the CU is much more forgiving.

    You may also want to confirm that the drain line away from the machine is clear. The drain pump is a mag-drive centrifugal pump and can not make a lot of pressure/head.

    BTW, the elevation of the membrane switch is critical. Basically, the height of the membrane will be the cut in level of the water.

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