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  1. #1
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141

    walk in freezer not going into defrost

    what would cause my compressor to keep runing while in defrost , this is a pumpdown system. changed time clock twice still same problem

  2. #2
    Join Date
    Oct 2012
    Location
    Torrington CT
    Posts
    82
    did you have your gages on the system if it was pumping down you would see the low side drop and the high side would go i know this might be basit but if that does not happen the liquid line secanord might not be closing

  3. #3
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    thanks ar. i am posting this after the fact as i tried to tell the senior tech to check solonoid and pressure cut out. i quess what i am asking is if my compressor never shuts off my time clock will never allow my defrost heaters to come on correct?

  4. #4
    Join Date
    Mar 2007
    Location
    NW AR
    Posts
    2,478
    Quote Originally Posted by royd2 View Post
    thanks ar. i am posting this after the fact as i tried to tell the senior tech to check solonoid and pressure cut out. i quess what i am asking is if my compressor never shuts off my time clock will never allow my defrost heaters to come on correct?
    Compressor shutdown doesnt initiate defrost, your clock does. Your compressor could continue to run while your heaters are energized.

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,946
    Quote Originally Posted by ar_hvac_man View Post
    Compressor shutdown doesnt initiate defrost, your clock does. Your compressor could continue to run while your heaters are energized.
    This is not necessarily true.

    Many times, the electrical circuit to the condensing unit is only large enough to run the compressor OR the heaters, but not both.

    Thus, there is often an interlock so that the compressor must cycle off before the defrost heater contactor can energize.

  6. #6
    Join Date
    Sep 2004
    Location
    Phoenix, Arizona
    Posts
    90
    Well on some larger systems the heater won't energize till compressor shuts off. Heater relay off aux contacts on compressor contactor. Your post #13 is a good starting point to check.

  7. #7
    Join Date
    Mar 2007
    Location
    NW AR
    Posts
    2,478
    I agree. I dont see them often but there are systems set up and wired that way. No offense to the OP but hes obviously lost(we all were at some point) so I posted what I felt he needed to tackle first.

  8. #8
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    defrost timer de-energizes ll solenoid valve and then compressor will run until pressure switch opens.
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  9. #9
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    ok thats what i thought so we need to check our elements and solonoid and pressure cut out then.

  10. #10
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    could a bad defrost termination switch also cause my heaters to not come on ?

  11. #11
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    idk somehow reading hotter temp than actual

  12. #12
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    ok thanks thats what we will try

  13. #13
    Join Date
    Jan 2012
    Location
    ohio
    Posts
    141
    i will post back tomorrow, thanks again

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