Page 1 of 2 12 LastLast
Results 1 to 13 of 16
  1. #1
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes

    Recognising coil ice-up symptoms.

    Does anybody have a theory on recognising the cause of an iced up coil early just by the location & pattern.

    If a drain was blocked ,depending on pan fall but the iced up section would be uniform or possibly at the opposite end of refrigerant entry.

    If there was a shortage of refrigerant or a metering device issue we would see it close to the entry of the coil.

    If a middle fan was not working we would see it in the middle & then grow from there.

    What do you guys think by visually looking at an iced up coil before trying to find the real issue ?
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  2. #2
    Join Date
    Feb 2007
    Location
    Ohio
    Posts
    285
    Post Likes
    I probably catch hell for this but completely iced over could have many causes, bad t-stat, bad setting on t-stat, someone left the door open, bad defrost clock if one is there, stuck open liquid line solenoid valve and so on. In my experience partially froze over is normally a low refrigerant charge or inefficient compressor.

  3. Likes fridg, UmmScott liked this post.
  4. #3
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes
    Thread Starter
    Quote Originally Posted by ReferTroop View Post
    I probably catch hell for this but completely iced over could have many causes, bad t-stat, bad setting on t-stat, someone left the door open, bad defrost clock if one is there, stuck open liquid line solenoid valve and so on. In my experience partially froze over is normally a low refrigerant charge or inefficient compressor.
    If caught early enough in the completely iced over scenario & the coil was not completely iced ,,,,, where would the ice formation mostly be for each of your possible causes.

    I know I'm asking a lot but just curious.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  5. #4
    Join Date
    May 2016
    Location
    DeKalb, IL
    Posts
    154
    Post Likes
    Pretty new to the field, so one of you better techs feel free correct me.

    Assuming it is caught early enough, it should be pretty easy to deduce the cause by the location, or at least get an idea right? Ice indicates two things: presence of moisture in the air, and that the coil/lineset is below 32 degrees F (0 C).

    In refrigeration applications, low temps are intended inside the enclosure, so freeze-ups (especially outside the enclosure) can be decoded as the presence of a problem via their locations.

    Ice over coil - low airflow to evap coil, or not functional/improper defrost
    Ice on cap tube/txv - restriction (as refrigerant flow is restricted severely, the pressure leaving the restriction is dropped significantly, causing temp drops more dramatic than intended)
    Ice on suction side of compressor - low refrigerant (suction side of compressor is lowest pressure point in system (system w/o restrictions), so it will ice first in a low refrigerant situation

    Excessive runtimes and humidity caused by constant opening of the enclosure can cause freezing to.

  6. #5
    Join Date
    Feb 2007
    Location
    Ohio
    Posts
    285
    Post Likes
    Low refrigerant the coil will be iced over from the bottom up normally, bad suction valves ice on the distributor tubes and the possibly the first row of fins leaving the distributor tube and depending on the severity of high suction pressure no ice formation at all. Bad thermostat, setting, defrost clock, etc would have a uniform ice formation over the entire evaporator with the exception of the very top early on. Restriction in one of the distributor tubes would leave that portion being starved and have no ice formation or very little.

    Quote Originally Posted by fridg View Post
    If caught early enough in the completely iced over scenario & the coil was not completely iced ,,,,, where would the ice formation mostly be for each of your possible causes.

    I know I'm asking a lot but just curious.

  7. Likes fridg liked this post.
  8. #6
    Join Date
    Feb 2007
    Location
    Ohio
    Posts
    285
    Post Likes
    Your fairly close with a few exceptions, the low refrigerant scenario will cause low suction pressure however being that the evaporator is already starved you won't get ice to the compressor. Liquid refrigerant traveling to the compressor is about the only way your going to get ice there with the exception of walk-in freezer where ice is normal on the suction line but only too the compressor, not on it.
    I'm also assuming this is commercial refrigeration and not air conditioning, commercial refrigeration the evaporator is always making ice (Low and Med temp.) except when the compressor is in the off cycle.

    Quote Originally Posted by Pajal View Post
    Pretty new to the field, so one of you better techs feel free correct me.

    Assuming it is caught early enough, it should be pretty easy to deduce the cause by the location, or at least get an idea right? Ice indicates two things: presence of moisture in the air, and that the coil/lineset is below 32 degrees F (0 C).

    In refrigeration applications, low temps are intended inside the enclosure, so freeze-ups (especially outside the enclosure) can be decoded as the presence of a problem via their locations.

    Ice over coil - low airflow to evap coil, or not functional/improper defrost
    Ice on cap tube/txv - restriction (as refrigerant flow is restricted severely, the pressure leaving the restriction is dropped significantly, causing temp drops more dramatic than intended)
    Ice on suction side of compressor - low refrigerant (suction side of compressor is lowest pressure point in system (system w/o restrictions), so it will ice first in a low refrigerant situation

    Excessive runtimes and humidity caused by constant opening of the enclosure can cause freezing to.

  9. Likes Pajal liked this post.
  10. #7
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes
    Thread Starter
    Quote Originally Posted by ReferTroop View Post
    Your fairly close with a few exceptions, the low refrigerant scenario will cause low suction pressure however being that the evaporator is already starved you won't get ice to the compressor. Liquid refrigerant traveling to the compressor is about the only way your going to get ice there with the exception of walk-in freezer where ice is normal on the suction line but only too the compressor, not on it.
    I'm also assuming this is commercial refrigeration and not air conditioning, commercial refrigeration the evaporator is always making ice (Low and Med temp.) except when the compressor is in the off cycle.


    Purely for Commercial Refrigeration my queries.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  11. #8
    Join Date
    Jul 2000
    Location
    Guayaquil, EC
    Posts
    14,302
    Post Likes
    The key is to learn how to "read the ice".

    Frost is new.

    Clear, hard ice is old.

    Buildups of frost or ice are caused by incomplete defrosts.

    Incomplete defrosting of frost creates clear, hard ice.

  12. Likes Pajal liked this post.
  13. #9
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
    Posts
    6,200
    Post Likes
    X2, icemeister. I was taught there is a reason why its called a "defrost time clock" and a "defrost cycle"!

  14. #10
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes
    Thread Starter
    Quote Originally Posted by icemeister View Post
    The key is to learn how to "read the ice".

    Frost is new.

    Clear, hard ice is old.

    Buildups of frost or ice are caused by incomplete defrosts.

    Incomplete defrosting of frost creates clear, hard ice.
    X3.

    The consistency or pattern of the ice is a good tool ,,, now I'm just trying to refine early diagnosis of location compared with pattern.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  15. #11
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes
    Thread Starter
    What causes snow inside Market Freezers ?

    Is it a defrost issue where the ice that has melted has now caused the water vapour to refreeze while fans are running creating a very light snow which just keeps building up ?
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

  16. #12
    Join Date
    Jan 2010
    Location
    Sea to Sky
    Posts
    3,518
    Post Likes
    Moisture infiltration, defrost too long, and/or no fan delay coming out of defrost.

    Sent from my SM-N910W8 using Tapatalk

  17. #13
    Join Date
    Apr 2005
    Location
    Australia : Queensland
    Posts
    1,845
    Post Likes
    Thread Starter
    Quote Originally Posted by BALloyd View Post
    Moisture infiltration, defrost too long, and/or no fan delay coming out of defrost.

    Sent from my SM-N910W8 using Tapatalk

    I do have facia anti-sweats not working but all seals are good. I'm going with defrost to long & fan-delay or drip-time not long enough.
    The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •