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  1. #1
    Join Date
    Nov 2010
    Location
    MN
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    146

    Ice build up freezer

    What causes ice to build up around the hole on a evaporator where the fan blades are, to the point where blades are scraping ice? Electric defrost, clear drain and clear coil. Called Señor tech and he stated defrost termination was going too long then he thought maybe it was too short. Any idea would be great, have 2 locations with this problem and I'm flipping a coin on which way I adjust defrost termination settings. Maybe that's not even the issue. Any input would be greatly appreciated.

  2. #2
    Join Date
    Jan 2013
    Location
    San Gabriel Valley, California
    Posts
    32
    Quote Originally Posted by PMARS2345 View Post
    What causes ice to build up around the hole on a evaporator where the fan blades are, to the point where blades are scraping ice? Electric defrost, clear drain and clear coil. Called Señor tech and he stated defrost termination was going too long then he thought maybe it was too short. Any idea would be great, have 2 locations with this problem and I'm flipping a coin on which way I adjust defrost termination settings. Maybe that's not even the issue. Any input would be greatly appreciated.
    hahaha, this is so simple.. muhahhahaha

  3. #3
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Well you haven't really given us much to work with here. Have you checked the heaters? Box infiltration? Stock room door guy have the door open all day? Timer initiating defrost? Is it stuck?

  4. #4
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by fengshvac View Post
    hahaha, this is so simple.. muhahhahaha
    Really? So what is it oh enlightened one? Teach us.

  5. #5
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,426
    It is often caused by no fan delay. Now you have to figure out why there's no delay.

    Obviously a bad termination/fan delay switch would do that, but there's other causes possible. if the clock is terminating defrost before the termination switch, the fans will start immediately. Causes for this could be be the defrost limit time set too short, heaters not working right, or excessive frost load.

  6. #6
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Is there also ice on the ceiling in front of the evap fans?

  7. #7
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by craig1 View Post
    It is often caused by no fan delay. Now you have to figure out why there's no delay.

    Obviously a bad termination/fan delay switch would do that, but there's other causes possible. if the clock is terminating defrost before the termination switch, the fans will start immediately. Causes for this could be be the defrost limit time set too short, heaters not working right, or excessive frost load.
    Yep

  8. #8
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,927
    I have seen it happen when the DFT was failed, and the cycle was ended only by the default 40 minutes, replaced a DFT a couple of months ago and problem solved. This can also cause icing on the ceiling, the higher temps cause the water to vaporize during defrost.

  9. #9
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,617
    Check the above mentioned defrost termination issues as well as air infiltration thru the door, box seams, pipe chases, untrapped drain, conduit, etc.
    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

  10. #10
    Join Date
    May 2005
    Posts
    1,349
    i just changed a fan delay for this same thing.

  11. #11
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,356
    I'd rule out any infiltration issues first. Since the coil is clear and ice is building up around the fans, this points to moisture infiltration in my book.

    In my experience, employees and/or vendors leaving the door open for long periods (or not fully closing it) will cause this problem. Positive door closing mechanisms and a door switch to kill the fans usually resolve it. Trying to educate them never does.

  12. #12
    Join Date
    Feb 2013
    Location
    Phoenix, Arizona
    Posts
    10
    It is often caused by no fan delay. Now you have to figure out why there's no delay.

    Obviously a bad termination/fan delay switch would do that, but there's other causes possible. if the clock is terminating defrost before the termination switch, the fans will start immediately. Causes for this could be be the defrost limit time set too short, heaters not working right, or excessive frost load.

    I agree with this Craig1 said. Also one more thing to check would be is it the right fan & blade installed? It may be improper air flow, or dirty coil in this area, check back side of coil.

  13. #13
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,927
    Infiltration and door open usually freezes the coldest part in the box first, the coil, fans wont frost up with no air flow through the coil, frost around the fans means humid air went through the colder coil, or the length of defrost caused vaporization and the vapor went to the next coldest spot near the coil and condensed there?

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