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  1. #1
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    I have a KM 450MAB giving me trouble which I can not figure out. On start-up, water valve opens for a minute, and then compressor starts - and it should be in harvest. Liquid line to TXV is real hot, hot gas line is not. Pressures = low - pegged, high side 350+ & shuts off on high head. I figured it was the hot gas solenoid. I can lift the coil off the solenoid, and it appears to be opening and closing, and I can hear the difference in sound, but no change on gauges.

    I pulled the charge, pulled the solenoid and strainer. I energized the valve and blew through it - clear. Strainer was clear. Blew down the hot gas line with nitro, and seemed to get it back on low side. Hooked it back up, weighed the charge, same problem. Off on high head. What the heck am I missing?
    called my Hoshi rep, and he said it's the coil, but how I don't know, cause it worked in my hand, and seemed to work installed. Hoshi factory - not much better - said maybe TXV, which doesn't make sense to me.

    Help me please.

    OK, OK, here's the deal, if you guys help me solve this, I'm gonna sign up to be a site supporter. This is driving me nuts.

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,325

    Hoshizaki KM450MAB............

    I have to say that it's the TXV is stuck open and thereby dumping all your refrigerant into the harvest loop and causing the high discharge pressure shutdowns.

    We have nothing much to go on here and from what you describe, it won't be easy to get a lot more info.

    If it were the liquid line solenoid not opening, it would run as if it were in freeze. If it were stuck open you would get a normal startup sequence and when it switched into the freeze cycle it would run as if it were in harvest, so I don't think it's the culprit here.

    Change the TXV.


  3. #3
    Join Date
    Jun 2004
    Location
    MidWest
    Posts
    64
    It sounds to me like the Hot gas valve, if it has power going to the coil from the board, is not opening while in refer loop. No matter how you look at it the hot gas valve has to have hot temp out of disharge during harvest. If it doesn't then you have the case you have now. I do believe the condensor fan on this model does not come on in harvest cycle. So you would have a very hot temp going to your txv since the fan does not come on in harvest. Maybe coil is fatigued under pressure. I say make sure you have proper voltage to coil during harvest and if you do you should have hot gas. Otherwise replace hot gas valve if no hot temp out of disharge of valve. Hope this helps.

  4. #4
    Join Date
    Feb 2004
    Location
    Western New York
    Posts
    1,047

    icemeister

    I know you understand ice machines, but hvacmd2002 said,

    "Liquid line to TXV is real hot, hot gas line is not."

    I say replace the hot gas valve. Or check power supply to the valve.

    Again from hvacmd2002, "I can lift the coil off the solenoid, and it appears to be opening and closing, and I can hear the difference in sound, but no change on gauges"
    Just means the pilot solenoid is working, not the valve.

    We have a potential site supporter here, lets get helpin'
    Experience is what you have an hour after you need it.

  5. #5
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611

    Re: icemeister

    Originally posted by baub
    I know you understand ice machines, but hvacmd2002 said,

    "Liquid line to TXV is real hot, hot gas line is not."

    I say replace the hot gas valve. Or check power supply to the valve.

    Again from hvacmd2002, "I can lift the coil off the solenoid, and it appears to be opening and closing, and I can hear the difference in sound, but no change on gauges"
    Just means the pilot solenoid is working, not the valve.

    We have a potential site supporter here, lets get helpin'
    I remember checking voltage to coil, because I was gonna throw in a 1/4" Sporlan solenoid to try to get it going. I believe I had 115v. But if I had the valve out, and energized, and I could blow through it with no restiction, isn't it working?

  6. #6
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,325

    baub.........

    I wholeheartedly agree that for the sake of site we must help find the proper remedy.

    I read all of hvacmd's points and attempted to boil it down to the logical basics.

    With the #1 assumption being that the HG valve is bad and the TXV is good what should happen during the start sequence on a Hoshi? You get water fill....he's got that. Then you go into what is essentially a harvest cycle. In the harvest cycle you have what?......80-100# SP and around 200# DP or something like that and to achieve this the HG valve has to be open. If it doesn't open, you're essentially in the freeze cycle. I don't see how the HG valve can cause the conditions observed.....open or closed.

    The observation that the line going to the TXV is hot makes no sense if the TXV is in fact good. The TXV should be closed down during the harvest cycle there is no way that the line going to it should be hot. The TXV is stuck open.

  7. #7
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611

    Re: baub.........

    [. In the harvest cycle you have what?......80-100# SP and around 200# DP or something like that and to achieve this the HG valve has to be open. If it doesn't open, you're essentially in the freeze cycle. I don't see how the HG valve can cause the conditions observed.....open or closed.
    [/B]
    But in harvest, the condenser an is off, so if the HG valve is closed (stuck or restricted), and we're in freeze (essentially) and the condenser fan is off because it's really in harvest = you'd get high head ?

    I don't know really. Just trying to sort through this

  8. #8
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    Well there is nothing like a Fluke two input thermo to find out. Take you temp across both valves and end the mystery.
    A Diamond is just a piece of coal, that made good under pressure!

  9. #9
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,325

    hvacmd2002........

    I completely forgot the fact that Hoshizaki doesn't energize the condenser fan motor until the "real" freeze cycle. Everybody else uses a pressure switch to cycle the fan at any time in any cycle.

    I think maybe you have figured out your problem.

    I think for me it's been a long hot day.

    Check the temps like frozen suggested. That'll tell you for sure.

  10. #10
    Join Date
    Feb 2004
    Location
    Western New York
    Posts
    1,047

    We will fix it!

    From hvacmd2002 "But if I had the valve out, and energized, and I could blow through it with no restiction, isn't it working?"

    Solenoid valves are controlled by the pilot valve and the inlet and outlet pressure. You have taken the valve out of it's operating range when "blowing thru it".

    Icemeister- hvacmd2002 said- "Liquid line to TXV is real hot, hot gas line is not." The E board thinks it's in harvest, trying to send hot gas thru the hot gas valve, but not open. Thru the TXV by default. The TXV senses high suction pressure and high superheat, so it is wide open.

    hvacmd2002- Is the condenser fan off during this event?

    Are we having fun yet?

    [Edited by baub on 07-26-2004 at 09:57 PM]
    Experience is what you have an hour after you need it.

  11. #11
    Join Date
    Jun 2004
    Location
    MidWest
    Posts
    64
    I think that is 3 people who agree now, including myself, hvacmd2002. The rest is up to you.

  12. #12
    Join Date
    Aug 2001
    Posts
    113
    You have invested way to much time on this machine. Replace hot gas valve with OEM and collect your money.

  13. #13
    This was fun fellas.

    I'm gonna pray that I get a batch of calls for SnotsMan cubers going bad and some Crystal Tips. of which there outa be plenty of out here.


    Then we'll have some more fun!

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