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  1. #14
    Join Date
    Jun 2007
    Location
    Arizona
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    100
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    Quote Originally Posted by Bworth74 View Post


    Received a call on this walk in freezer another company installed. System is remoted 2 floors above box. R448 refrigerant with -10 setpoint for Freezer. Looks like this unit has an MOP txv valve at 35 psig. Has a headmaster valve for 225 psig. Unit is actually at temp but looks as if in the colder mornings and nights it may be low on charge causing this iceing issue. I will have more info tomorrow. Just wanted some initial thoughts.
    how is this defrosting ? hot gas or electric ?? how many times a day and what is the duration ?? is there any termination ? are the fans shutting off in defrost ?? more information is needed

  2. #15
    Join Date
    Aug 2018
    Location
    Fort Worth, Tx.
    Posts
    92
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    Thread Starter
    Sorry still scheduling with customer to get in and make a good diagnosis. I will post as soon as I have the information.

  3. #16
    Join Date
    Oct 2011
    Location
    Harrisburg, NC
    Posts
    1,046
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    Something interesting to note that I see when people start working with a new refrigerant.

    They seem to forget basic refrigeration diagnostic methods

    Charge, Superheat, operating pressures, defrost lengths and proper termination, etc.

    I have done a lot of work with R448a both Racks and Self contained/conventional. It runs almost the same as R22, but lower discharge temps.

    Go through from start to finish and make sure it's all operating correctly, I bet you will find the problem along the way. It's just a freezer.




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    I can't fix it if it won't stay broke..

  4. #17
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,340
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    Bad CalRod at the top of the evap perhaps?

    Demand defrost or a timer?

  5. #18
    Join Date
    Mar 2007
    Location
    In the Conservatory with a Lead Pipe
    Posts
    15,199
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    The ice pattern out the txv is odd

  6. #19
    Join Date
    Oct 2011
    Location
    Chicagoland Area
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    6,674
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    Quote Originally Posted by itsiceman View Post
    The ice pattern out the txv is odd
    I think that's just excessive moisture and nothing more
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  7. #20
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,390
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    Something I found odd with 448a was the listed defrost times from Zero Zone for a multideck med temp case was 6 times a day vs 4 times a day with 404a.

  8. #21
    Join Date
    Mar 2007
    Location
    In the Conservatory with a Lead Pipe
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    Zero ice build up on or closer to the TXV is not odd to anyone?

  9. #22
    Join Date
    Jan 2016
    Location
    The triangle in the Keystone
    Posts
    985
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    Looks like it’s been having long cycles. Could be undercharged.

    Is that element pulling out of the coil in the first pick? Is the seam on the ceiling above it separating and silicones together?

  10. #23
    Join Date
    Oct 2011
    Location
    Harrisburg, NC
    Posts
    1,046
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    Quote Originally Posted by itsiceman View Post
    Zero ice build up on or closer to the TXV is not odd to anyone?
    Not one bit. Means it's metering correctly to the nozzle in the distributor. If that section was frosted I'd be telling the tech to check the strainer.




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    I can't fix it if it won't stay broke..

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