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  1. #1

    Hoshizaki Km-630MAB...not harvesting properly

    So to begin, I am working on this unit that had first a burned out water pump so that got replaced and from there we found more problems with this unit. After running the first cycle, we noticed that not all of the ice dropped, in fact,maybe about 3/4 of the ice produced never made its way down. After talking to the owner, I was able to finally spill the truth and telling me that for 7 years he didn't do any cleaning on it and while checking the evaporator, we noticed build up. So it got cleaning 3 times in a row with brushes through the evaporator and the distribution tubes as well with the solution that Hoshizaki suggests. Once that got done, we ran the unit again and noticed that the ice harvest increased by maybe dropping more than half the load or so...but obviously not enough so after inspecting the evaporator for faults or damages and after also having cleaned the outdoor coil(That was done with the replacement of the pump, it was really dirty), it still did the same thing. I didn't want to put my gauges until i had reached a point where i couldn't see a problem and this was it. The few ice cubes that it dropped, the size was good and nice shaped cubes. I plugged in my gauges and could only see suction pressure. While we turn on, theres the water fill and then the harvest cycle turns on for about 3 minutes and the pressure read 40-45 psi on R-502. When i called the manufacturer it told me it should be reading 60-75psi and when it switched to freeze cycle after 3 minutes I let the machine run for some time. 10 minutes into freeze cycle i read the pressures and it started at 40psi and worked its way down to 21psi no lower than 20psi. Asking the manufacturer, they told me that this was right on. The time for freeze cycle is spot on between 30-35 minutes when it switches to harvest. But it is at harvest when it can't perform. I was suggested that it could be the txv and that i should replace it thinking that it may be letting refrigerant through and cooling off the defrost refrigerant (this was suggested by the Hoshizaki tech) I am just wondering to see if I can get any ideas on this unit because it's def. picking my brain. I just want re-assurance in the Hoshizaki people. Could I also be looking at the problem with the defrost valve?

    Thanks for anyone's input.
    If any more info needed i'll be happy to provide.

  2. #2
    Join Date
    Oct 2008
    Location
    Winnipeg, Manitoba, Canada
    Posts
    118
    Is it water cooled? If so the water reg valve could be leaking by on harvest.

  3. #3
    This unit is an air cooled unit

  4. #4
    Join Date
    Apr 2010
    Location
    Wake Forest, NC
    Posts
    35
    What is the incoming water temp? What is the ambient temp? Do you get good waterflow through the inlet water valve during harvest so that it goes all the way to rear of evap plates? What is the discharge pressure?

    Based on model # this is an air-cooled unit.

  5. #5
    The water temperature ranges from 45-50 degrees and as the fan runs it increases a little more to no more than 60. The ambient temperature is about 70 degrees and the water flow in the evaporator to the rear of the evap plate is good, we inspected that previously since we were also recommended by hoshizaki to do that. The initial water pressure going into the ice machine is about 60psi.

  6. #6
    Join Date
    Apr 2010
    Location
    Wake Forest, NC
    Posts
    35
    That water temp sounds too cold, could be part of problem.

    How long does it stay in harvest when it's dropping ice, and what is the head pressure in freeze and in harvest?

    Suction line thermister is what takes it out of harvest when suction line reaches 50 degrees; something you could check with a temp probe.

  7. #7
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    6,790
    "Could I also be looking at the problem with the defrost valve?"

    The inlet water does most the harvest work on this machine.
    It should run fine on that temp also.
    Harvest time after freeze would help.

    You should be able to measure temps to diagnose a bad txv in harvest.

    As far as water pressure it will not tell you much on this machine.
    You need a min flow rate of 2.11 GPM and need to measure it. Check the water inlet screen if you haven't already.

    Did you clean the inside path through the evap while cleaning the outside ?

    If it was as bad as it sounds that could be an issue.

    Also FWIW I've seen plenty of separated evap tubing that will make ice fine but not harvest. This will kick you out early before all the cubes have dropped also.

    Could be many things unfortunately.
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  8. #8
    sounds like a hot gas valve failing to open. does it have 2 hot gas vlaves? Anyhow thats where i would start if the pressures are there. Ask wat pressures shoul;d b at harvest if they dont get high enough it wont drop...Id save the charge in a clean bottle replace the valve. reuse charge... if pressures are right of course...

  9. #9

    so does

    this sound like a good ANSWER. There could b seperations on solder joints but if u got a hot gas valves being 2 u can feel them at harvest if u place ur hand right after the valves and it gets redhot u got a block should only get redhot at the plate... some valves u can even take apart and clean may drop a few times only so replace it dont try to skimppp

  10. #10
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    6,790
    Quote Originally Posted by allamericanclow View Post
    sounds like a hot gas valve failing to open.
    So is it a 3 min harvest or a 15 min. harvest?
    No hot gas or bad TXV would get you a long harvest.

    From what I'm getting from the story it sounds like its cycling too fast thru harvest but, with out a time............

    To me sounds like the suction line is getting too warm too fast and not warming the whole plate to me but with out the suction temp..........

    “If You Can Dodge A Wrench You Can Dodge A Ball”

  11. #11

    so like i was saying

    3 min is a good valid harvest when u hear the crack u can hear the hotgass open pressure rise is fast. with a manotowic pressure needs to get over 50 for at full harvest. so if half the plate drops and half doesnt u can b assured the hotgas valve is bad.. unless ya pressure gets over 50... and it doesnt drop. well if u have an equal part that doesnt drop its the hotgas valve. and if u saw chipping on the plate from someone chipping ice then u need to get that person away from ur equipment... 3 words ho t gas valve. been there domne that u described it to a t as wlell as the manotowic

  12. #12
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    6,790
    aac On a Hoshi 3 min sucks if all the ice has not fallen off yet.

    For harvest cycles between the two

    Mani uses HG and gravity only and sometimes air.

    Hoshi uses water mainly and some HG.

    IMO on a Hoshi the HG valve is there to just slam shut the txv

    Manitowoc should be left out of this thread or the poor guy will be going in circles
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  13. #13
    Join Date
    May 2006
    Location
    Amory Mississippi
    Posts
    1,002
    Quote Originally Posted by itsiceman View Post
    aac On a Hoshi 3 min sucks if all the ice has not fallen off yet.

    For harvest cycles between the two

    Mani uses HG and gravity only and sometimes air.

    Hoshi uses water mainly and some HG.

    IMO on a Hoshi the HG valve is there to just slam shut the txv

    Manitowoc should be left out of this thread or the poor guy will be going in circles
    I was thinking the same thing. Mani and Hoshi are two different animals.

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