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Thread: scotsman Help!

  1. #1

    scotsman Help!

    I have a Scotsman M#CU1526SA-1A. S#090413200140 first came up to it and it was pretty limed up. And I had ice on the bottom but not the top of evap. Suction was at 60 psi and 300 head with a 70 degree ambient. No leaking dump valve no leaking hot bypass valve. It was cold on one side warm on the other. Also I found the plating coming off the evap. Called tech support and gave them all the readings. I had 20 deg superheat 404 system. Theirs been ppl messing with it. Tech said bad evap the txv would be pulling low suction pressure if it was bad. I knew with the plating coming off the evap had to be replaced. So I took everything apart. Cleaned everything. Water level and water temp sensor. Pump, bridge sensor, valves, water trough. Replaced evap, drier. Took condenser coil out and cleaned with coil cleaner. It was restricted pretty good. Put everything back together. Now the water level comes almost to the top of trough. The sanitizer light stays on. And the darn thing does the same thing ice on bottom but not the top. Its ready on bottom but the top has a little ice.now I have 50psi suction and 205 head. I weighed in charge. No leaking valves. I'm thinking txv?

  2. #2
    Join Date
    Aug 2002
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    Southold.calm
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    6,355
    Ice on bottom and little to non on top is a sign of leaking fill valve.

    Check your pressures with the manual
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  3. #3
    Join Date
    Jan 2013
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  4. #4
    OK I double checked the water inlet. It fills to proper level then shuts off I can hear it. The water never gets higher. And I can see the drain and no water is coming out.so I replaced the txv. Pulled vaccume to 200 microns and weighed in 12 oz R404. When I first turned it on I had 210 head with a 80 psi suction. I'm freaking!!! As the water gets colder the suction drop to 60. It ran for ever only got to 50 psi. And it should be 35 at the end of freeze. At one point the water stopped at ice was in the water the water froze. Then it was good. The difference now is both lines coming out of the evap are frosted. And it makes ice on the evap even. But it takes for ever. When it did go into harvest the ice barely came out and just started melting. It was still too thin. Plus I still got high suction. I tried unplugging the pump. And the suction dropped to 30 in about 4 mins. I'm going crazy. The hg valve is cold on one side and warm on another.

  5. #5
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    683
    How are you so sure the harvest valve isn't leaking? If water isn't leaking into the sump during freeze, then you only really have two possibilities: leaking harvest valve or weak compressor. Pinch off line to harvest valve, and if that doesn't fix it, it is a weak compressor.

  6. #6
    Join Date
    Aug 2002
    Location
    Southold.calm
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    6,355
    Quote Originally Posted by darrin0819 View Post
    OK I double checked the water inlet. It fills to proper level then shuts off I can hear it. The water never gets higher. And I can see the drain and no water is coming out.so I replaced the txv. Pulled vaccume to 200 microns and weighed in 12 oz R404. When I first turned it on I had 210 head with a 80 psi suction. I'm freaking!!! As the water gets colder the suction drop to 60. It ran for ever only got to 50 psi. And it should be 35 at the end of freeze. At one point the water stopped at ice was in the water the water froze. Then it was good. The difference now is both lines coming out of the evap are frosted. And it makes ice on the evap even. But it takes for ever. When it did go into harvest the ice barely came out and just started melting. It was still too thin. Plus I still got high suction. I tried unplugging the pump. And the suction dropped to 30 in about 4 mins. I'm going crazy. The hg valve is cold on one side and warm on another.
    Evaporator plate separation?
    Bad Valves in pump?
    That machine is too small to be guessing and putting a lot of parts in. Replace it.

  7. #7
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    683
    Wow I initially thought this was a 1500# unit based on model number; didn't realize it's an under counter unit. I agree with Pec, you already have enough evidence to condemn the unit: evaporator plating coming off plus refrigeration issue. Recommend replacement.

  8. #8
    I first replaced evap. It was under warranty. After that tech support said bad txv. Replaced that now I got height suction. 85psi start 55 when done it takes over 30 mins to make a batch. Comp is running 6 amps which is in spec. Now Scotsman is sending a different txv. Since I'm getting 3-5 deg superheat. Said that unit should be10-15 superheat?

  9. #9
    Although we had an ice machine in school, I've never worked on this machine. Read part of book supplied. I would be focusing on the freeze cycle. Superheat shared - book says good for model. Although you weighed in charge, curious to know what subcooling is. Didn't see that in book. Would verify charge, yes?. Also I would focus on Freeze cycle and specifically how water is coming in contact with evap. "At start up the controller operates the water pump and purge valve to drain the reservoir. The float valve refills the reservoir after the purge valve shuts off. When the reservoir has filled, the
    compressor and water pump start. After the discharge pressure has increased past the cut in point of the
    fan pressure control, the fan motor(s) will begin to operate and warm air will be discharged. The fan
    motor will switch on and off as the discharge pressure rises and falls. Water flows over the evaporator as
    the refrigeration system begins to remove heat. When the water temperature falls to a preset point, as
    measured by the water temperature sensor, the controller shuts off the water pump for 30 seconds. The
    freeze cycle resumes when the pump restarts and ice begins to form on the evaporator. As it forms, the
    water flowing over the ice moves closer and closer to the metal tip of the ice thickness sensor. When it
    comes into contact with the sensor for a few continuous seconds, that signals the controller that the
    freeze cycle is complete. Last question - Does evap have distributor? If so, could top part be malfunctioning?

  10. #10
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    683
    No offense to Scotsman tech support, and they may end up being right, but 55# at end of freeze is around 20 degree SST. You said it is supposed to be 35# which is more like 2 degree SST. When the old txv was in place you had 50# and evaporator was starving with uneven ice fill pattern. More with a new txv you have suction at 55 but even fill pattern. I find it hard to believe that by increasing superheat by 5 degrees you will magically drop your SST by 18 degrees. I still think it's a weak pump. I don't care if the compressor pulls 6 amps, if it takes 4 minutes to get the suction down to 35# with water pump off, ASSUMING the harvest valve its not leaking by, then I'm betting the compressor is weak.

    Again I would pinch off harvest line to see if that changes pressure and freeze time, and if not I would condemn compressor. Alternatively I may pinch off suction line to confirm compressor can pull a vacuum.

  11. #11
    Guys I appreciate all your help. This is why I'm reaching out. I'm going by tech support cause the evap and comp is under warranty. But their answeres don't make since and I agree with you. Good name what do you mean by evap distributor? It does shut the water off for 30 sec. Trippointlo. I agree. Their sending me the new txv at 10 am in the morning. Tech support still don't think the comp is bad. Before I replace the txviI'm buying a pinch off tool. I'm going to pinch off the hg valve see if my pressures drop. Or if it freezer faster. And last I'm going to pinch off the suction line. When I do what should I see. I never really do it on can comp. Just big semi. I mean I learned to unplug the water pump from this place. But I don't know what I should be looking for. It should drop to what in what time? Thanks for info

  12. #12
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    683
    With suction line pinched off it should pump into a vacuum pretty quick. As in around 3 to 5 seconds typically, maybe 10 seconds max. Obviously the bigger the compressor the quicker it pumps down, and the higher the suction pressure when you start the longer it takes, etc..

    Just make sure wherever you pinch it off, you will have room to cut it out and put a coupling afterwards... obviously don't pinch the actual harvest valve stub or compressor stub

  13. #13
    I know when I check the valves on a semi I close the service valve see how long it takes to get in a vac.then I unplug power to see if it holds. That's on 1 to 1 1/2 HP. If it rises right away I was told to replace valve plate. Do you do the same for the small can comp? I understand what you mean by making sure I save room to hook the lines back up. When you guys braze. Do you let nitrogen in? Do you have a special regulator? Cause I was taught to not use nitrogen ever. I tried using my nitrogen with a reg regulator. Yea let's just say I couldn't stop it from leaking. I'm going to go today to see what happens. I'll post back

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