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

    Lightbulb

    I have a Manitowoc QY1094N remote. On the original call (about 45 outdoor ambient)a few weeks ago, it was flashing a 2 code - 3 consecutive harvest over 3.5 minutes. It would make a perfect sheet in about 10 minutes, and then would not drop the sheet. It was loose on the lower half tho. Pressures during freeze were perfect, by the book. In harvest, low side was about 80# (book calls for 65 to 90). High side was about 155#, considerably lower than the book (180+).

    I figured if I had 80, sometimes 83#, I had the heat to drop the sheet. Didn't happen. I ran it through a clean cycle with Nicklesafe. Nothing. I called my distributor, who is usually very good. All they do is Manitowoc. He was stumped and had me call the factory. I called and left the job, waiting for them to call back.

    Manitowoc called back and suggested I had scale on the evap. He told me to dry the plate and look at it then. OK, did that, cleaned the plate with a soft bristle brush as suggested - nothing. Recovered the charge - I was missing 4#, and I figured I solved the problem. Nope. Same pressures in freeze & harvest - no change. Same outdoor ambient.

    Called the distributor again. He had me connect to the receiver and dump gas into the low side in harvest. Brought low side to 90# and the sheet dropped easily in 2.5 mins. Hmm.. maybe a bad HPR valve. But the book says harvest pressure is 65 -90#. And the HPR is giving me 80-83#. What's a new HPR gonna get me?

    That's the question. Should I find an adjustable valve so I can get 90#? Any other ideas?

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,265

    QY1094N........

    You don't mention the age of this machine, as in a serial number, but if it's within three years old the HPR valve would be covered under warranty, parts and labor. It probably has the original Alco valve and they have had a dismal failure history. The replacement Sporlan resolved most HPR issues with Mani remotes. The book says the Sporlan is non-adjustable, but it has a red cap covering the adjustment screw. Manitowoc tells us it's not really there.

    The added gas from the receiver to the defrost loop obviously improved your situation, but 2.5 minutes isn't anything to write home about, if you get my drift. A new HPR adjusted to around 100# ideally may get you by for now, but I suspect from my experience with many Manitowocs of late that the evaporator surface is on its way out......as in being etched from the effects of the chlorine and such in the water supply.

    The older machine had nickel plated copper evaps that would fail with flaking of the plating exposing the copper beneath. The grids often separated as did the tubes behind. These newer units have a alloying plating process where the nickel becomes alloyed with the copper, not plated. They don't flake, they simply fail to drop the ice.....no obvious defects to hang your hat on. I have a bunch machines in my shop right now, all with failed evaps......some only slightly more than five years old.

    I would propose to your customer that the new HPR should help, but there will be no guarantee that the evap is not going to arise as a new problem shortly. If the machine is under 5 years old, the evap is still under Manitowoc's warranty, but they are real stubborn about authorizing a replacement and may kick it back to you once it reaches the factory and undergoes an thorough inspection. If the customer opts for replacement under warranty, require full payment up front and issue a warranty credit once it clears inspection.

    Then sell the customer a Hoshizaki.

  3. #3
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    Thanks Ice. It's a '99. It was used 3 years, went to auction (business closed) and was stored for 2 years. I found the notes (stuffed in the back of the unit) from the previous guy that worked on it in '02. He had the same problem. He also had all the 911 numbers for everybody.

    It is an Alco valve. The plate looks real good, shiny even. I've dropped ice from plates that really looked like crap. Nothing loose, not worn, weep holes open.

    But with regards to etching. OK, stupid question. What exactly does it look like?

  4. #4
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,265
    Originally posted by hvacmd2002
    But with regards to etching. OK, stupid question. What exactly does it look like?
    The ones I've dealt with look somewhat less than shiny.....not a dull gray like the older ones got, but a more like grandma's silver that hasn't been polished since Easter Sunday.

    If yours is like new shiny, it's unlikely the surface is compromised. Change out the HPR and go from there.

    Good luck.

  5. #5
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,571
    I think you will find the copper tubes pulled away from the back of the evap not allowing good contact between the how gas lines and the plate. Manitowoc had alot of ploblems with certain machines in that ERA!
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  6. #6
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    Thanks Freeze. But I wonder.

    Freeze time is real good. Freeze pressures are real good.
    Ice sheet looks real good - uniform top and bottom.

    So, can all the above be good and I still have separation?
    I'm asking because I don't know. I've never seen a plate separate.

  7. #7
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,265
    The older Manitowocs had separation ills to be sure. If the tubes are separated to any degree, this condition will indeed hinder proper harvest but will usually show up as an uneven freeze pattern. The tubes about two-thirds of the way up tend to go first, then the bottom tubes. You would see these areas freeze more slowly, often mostly filling in near the end of freeze.

    If you suspect tube separation, (I don't at this point) you can remove the evaporator mounting screws on both ends on the evap assembly and gingerly pull it away from the bulkhead slightly and inspect the tube condition with a bright light and a long flat bladed screwdriver.

    I haven't seen any of the newer alloy plated evaps separate, just a lot that will never consistently drop within 3.5 minutes no matter what you do to the rest of the system. Only a new evaporator cures these machines' ailment. Most every customer goes for a new machine at that point.

  8. #8
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,571
    It seems to start in the top left, second row from the top and expand. This is the only reason for the defrost problem if the evap and pressures are good, you do not need to re-engineer the thing!
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  9. #9
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,571
    Ice, i have seen it on the newer plates, just the very wide plates with alot of expansion room.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  10. #10
    Join Date
    Jul 2005
    Posts
    947
    Machine level?

    I'm a basic kind of guy.

  11. #11
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    Originally posted by hvac_czar
    Machine level?

    I'm a basic kind of guy.
    The sheet's not loosening. I can pull the bottom half out. The top is still stuck from about halfway - up.
    And is does drop when I pass gas to the HG loop. All cubes are fully formed in the back too. Not like it's sitting there melting during harvest.

  12. #12
    Join Date
    Jul 2005
    Posts
    947
    I'd go with Icemeister then, good advice from a seasoned pro.

  13. #13
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    796
    Another thing to check is

    make sure the plate is on an angle so the block can slide straight off in to the bin.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

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