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  • Manitowoc Indigo curtain stays open too long and triggers bin full.

     fixbear updated 3 weeks, 4 days ago 4 Members · 23 Posts
  • AK626

    Member
    March 7, 2021 at 2:27 pm

    Manitowoc Inigo NXT 450 ID0452A

    I am having random issues during harvest cycle. The machine will go in harvest cycle like it’s suppose to, but most of the time the curtain will stay open for too long and it will go into “Bin Full” state when it’s not really full. And literally after 2 seconds the ice sheet will fall and close the curtain, but now the machine will wait 3 mins before it will start making ice again. Some times I will get lucky and the ice sheet falls right before the cut off time to trigger bin full and next cycle starts normally.

    What is a normal harvest time? If I remember correctly, the ice dropped around 2 min mark during harvest cycle when it was new. Now it takes little over 3 mins and it’s not a perfect cube due to long harvest time.

    I have cleaned the ice machine multiple times and it looks pretty clean. I have also replaced the water filter and ice thickness probe to rule that out too.

  • fixbear

    Member
    March 8, 2021 at 9:01 am

    Start by cleaning the machine with Manitowoc cleaner. And checking with a level that the machine is level. Being level front to back is mandatory for reliable harvest. The evaporator gets a fine mineral build up that you can’t see when it is wet. Follow the instructions in this operation manual for a full cleaning. Or you can use this Service manual, starting pg 37.

    What is the ambient temp of the room it is in? Does the ice sheet have a full bridge that makes the ice fall as one sheet or does it fall in pieces? Is the ice bridge 1/8 inch? Is the ice sheet even from top to bottom, side to side? Harvest time should be 1 to 2.5 min.

    Now if it does not harvest in under 3.5 minutes, the machine will add water and use it to assist with harvest. This depends on your firmware version.

  • AK626

    Member
    March 8, 2021 at 12:38 pm

    I have cleaned the ice machine multiple times and seems clean. The evaporator feels smooth when dry and no visible build up. Ice machine is leveled. Ice bridge is 1/8 inch and falls as one whole sheet and even all across. Ambient temperature 70 degrees.

    You are right about machine adding water to assist during harvest. I do notice after the help of water the ice sheet gets the final push. I just don’t get it. The ice sheet completely separates from the evaporator and seems like the water thickness probe and curtain holds it from falling easily.

    How long should the freeze cycle be? I am aware the answer will depend on my incoming water temp and ambient temp. But does 21 mins for freeze cycle (not including the “Pre-Chill” cycle) sound about right?

    • fixbear

      Member
      March 9, 2021 at 1:32 pm

      What does the back of the cubes look like after harvest. Sharp square corners or kind of melted out a small bit? Also inspect the grid vertical bars to be against the evaporator. Sometimes the freeze cycle expanding ice tends to lift them slightly. Then the cube gets a hook under the bar that delays harvest. A light plastic mallet and a piece of wood work well for reseating them.

  • olivero

    Member
    March 8, 2021 at 1:37 pm

    If the grid has parts that are loose, it may be hooking the sheet of ice and keepin git from falling easily, sometimes it’s hard to see. Happens to Scotsman units.

    • AK626

      Member
      March 9, 2021 at 5:03 pm

      I tried to wiggle them but they are firm.

  • fixbear

    Member
    March 9, 2021 at 1:00 pm

    Freeze time is about 11 to 12 min. You can find that information in the service manual on pg 230. You may have a undercharge. Are you a refrigeration tech with EPA certification?

    • AK626

      Member
      March 9, 2021 at 5:05 pm

      I am not a tech. I am in a small town where there isn’t any ice machine tech. I have a AC guy helping me.

  • fixbear

    Member
    March 9, 2021 at 1:25 pm

    If the Curtain is staying open, The ice sheet is not harvesting evenly. Or the curtain is not in the pivots correctly. Or something is preventing the curtain from closing the magnetic switch. Or the water tray is not in the correct position.

    Basically, once the ice is free from the plate, it has to fall as one piece immediately. If it leaves the s plate and hangs against the spray shield it will hold it open. As soon as you see the ice start to move forward at the top it should drop in only a few seconds. If it’s not, you have to find what is restricting it. Make sure the spray cover sets evenly against the evaporator when at rest. I have come across some that were mishandled and had a warp. If it’s on the magnet side, that is a problem.

    Also, when you clean the machine, do you remove the sump, spray bar, thickness probe, and water level sensor? They have to be hand cleaned after the 24 min circulation with a nylon brush. Be very careful to rinse and dry the thickness sensor.

    • AK626

      Member
      March 9, 2021 at 5:13 pm

      I took everything apart and soaked it in the solution and cleaned it thoroughly. I also saw an YouTube video where someone was having same issue as I and he fixed it by spraying the evap grid with 50/50 ice machine cleaner and scrubbing each cell with a soft brush. It definitely helped the harvest time for me but not quite there.

  • fixbear

    Member
    March 9, 2021 at 1:47 pm

    I forgot to ask you if your machine has air assist harvest. In the later versions they added a air compressor to assist harvest. It comes on when the hot gas valve is energized and pumps a small amount of air into the evaporator face behind the ice to break the suction.

    • AK626

      Member
      March 9, 2021 at 5:14 pm

      I don’t think so. Would you be able to tell by Serial number? It is 1120373916

  • fixbear

    Member
    March 9, 2021 at 1:54 pm

    If you go into the service menu and check T3 and T4 during harvest it will shed a bit of light as to the unit’s charge level.

    • AK626

      Member
      March 9, 2021 at 5:30 pm

      I saw that last night. T4 was all over the place from 90 to 160 degrees. From my finding T3 and T4 should have no more than 12 degree difference. T3 is anywhere from 10 to 25 degrees. So because of the wide difference, I have E7 Starving TXV. Tracing where T4 is hooked up, the line is freezing cold, about same temperature as T3. That tells me T4 is malfunctioning. I’ve ordered a replacement and should have it tomorrow. I am not sure replacing T4 will fix anything since, correct me if I am wrong, all those thermistors don’t have any effect on operation. Aren’t they there for diagnosis purpose?

      • fixbear

        Member
        March 9, 2021 at 7:43 pm

        I am not sure replacing T4 will fix anything since, correct me if I am wrong, all those thermistors don’t have any effect on operation. Aren’t they there for diagnosis purpose?

        Wrong. They are the machines sensing that the AI uses for more efficient operation and alarms. Our being able to read them is just a convenience to us that makes invasive testing less necessary.

  • AK626

    Member
    March 9, 2021 at 5:35 pm

    During harvest cycle T2 starts off at around 175 degrees but within 30 seconds will drop to 95 degrees and hover around there. Is this normal? I thought T2 needed to be over 150 during harvest cycle.

  • AK626

    Member
    March 9, 2021 at 5:49 pm

    One more thing I would like to add. There are 6 small red LEDs on the board. 2 of which are for Left Harvest Valve and Right Harvest Valve. During harvest cycle, only Left Harvest Valve lights up, there is a LED for Right Harvest Valve but it doesn’t light up. Is this normal?

  • olivero

    Member
    March 9, 2021 at 8:05 pm

    IF this is anything like a Scotsman (which I assume it is) then the sensors are detecting if the curtain is open.

    IF it’s 2 evap plates, then 1 of them has a harvest sensor with the idea that when one hits the harvest point, the other one has as well, then a hot gas solenoid kicks in, warming the plate and eventually a harvest assist mechanism helps to remove the plate by either punching the sheet or gently pushing it out.

    That’s in a Scotsman, but I assume they are similar.

    Each door has a curtain switch mounted on the curtain, if there’s 2 curtains, then there’s 2 switches, and if one is not reading it’s open, then that’s a problem as it never registers that it’s harvested.

    When the curtain stays open, it means that the bin is full and ice could only fall slightly, holding the door open.

    That’s the theory behind it.

    So is it 2 evap plates or 1? If it’s 1, then there should only be one indicator LED lighting up, if there’s 2, then both should light up when the curtain is open,

  • fixbear

    Member
    March 9, 2021 at 8:57 pm

    You have a single evaporator, TXV, and harvest valve. The same controller is used across the whole line. The thermistors are as follows on your machine; T1 is the liquid line out of the condenser. T2 is the compressor discharge. T3 is the evaporator inlet temp. T4 is the evaporator outlet. On other models these probes are placed and programmed different. If you had a bad thermistor, you would have a alarm indicating it. They are easily tested with a ohm meter. Values are in a chart in the service manual.

    At the start of the freeze cycle T3 should be about 23F and drop slowly as the ice forms to about -9F. Suction pressure is a better indicator. During Harvest, T2 (compressor) should start about 87F and drop to 65F. Again, gauges are a better indicator. Remember, that when the harvest valve opens, it drops most of the load on the compressor. Discharge just is vapor going through the evaporator. If you watch T4 during the harvest you will see it go from freezing to about 40 to 50 degrees before the ice drops. You should not see the compressor discharge above 150 in any part of the cycle. If you do, (providing the fan is working correctly) look for line damage between the compressor and condenser. Or Check valve is not opening correctly. It’s between the harvest valve and the condenser to prevent back feed of liquid during the harvest. But that would shorten the harvest time. Not increase it. Get a good accurate thermometer and a ohm meter and test any suspect thermistors before getting in to deep.

  • IcemanJon

    Member
    March 11, 2021 at 8:37 am

    Hello there, this is Jonathan at Manitowoc Ice Service department. I would highly suggest a call to tech support at this point. Especially seeing as the warranty on this machine runs out 3/12/21 (Tomorrow)! Call 1-844-724-CARE

  • fixbear

    Member
    March 11, 2021 at 5:55 pm

    Nice of you to jump in Icemanjon. Let us know what comes out of this.

  • AK626

    Member
    March 25, 2021 at 4:22 pm

    The issue I was having is fixed. Cleaning the grid with toothbrush and ice cleaner solution seems to have fixed the issue. Thank you guys for your help.

  • fixbear

    Member
    March 25, 2021 at 7:32 pm

    Two questions, Did you use Manitowoc cleaner? And was it ever cleaned with a generic ice machine cleaner or another acid. What happens is the evaporator can get etched if the cleaner is wrong. Microscopic pitting.

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