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  1. #27
    Join Date
    Feb 2012
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    Alabama
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    378
    Agreed Mark. But the OP was asking how they worked, signifying he was unfamiliar with them enough to troubleshoot them. Sometimes when inexperienced on something you lack confidence. The ohms test was just a way for him to double check.

  2. #28
    Quote Originally Posted by mark beiser View Post
    Why bother though, if you measure 240v across the the contacts when they should be closed, you already know the sequencer is bad.

    It is better to test the circuit in normal operation anyway.
    If the contacts are pitted/burned, it is not uncommon for them to sometimes close OK, especially absent the line voltage because of the lack of arcing as they close.
    You can actually end up with a set of contacts that fails under normal voltage and current conditions, but passes a continuity test when it is not switching line voltage.

    Similar thing for a sequencer that is stuck closed.
    The act of disconnecting the wires from it to do a continuity test can disturb it enough to cause the contacts to unstick and open.
    I know that and you know that but I remember when I was new to the industry and some things that seem simple now were very confusing at times and it helped me to understand things if I reduced the number of things going on like in this case I remember doing the same thing (taking line voltage from sequencers to test only the sequencer) sometimes I would try and overthink things it helped me understand is all .. thought it might help this guy too.

  3. #29
    Join Date
    Jul 2009
    Location
    South Carolina
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    3,221
    Quote Originally Posted by RobFarns View Post
    I know that and you know that but I remember when I was new to the industry and some things that seem simple now were very confusing at times and it helped me to understand things if I reduced the number of things going on like in this case I remember doing the same thing (taking line voltage from sequencers to test only the sequencer) sometimes I would try and overthink things it helped me understand is all .. thought it might help this guy too.
    I can't argue with yours & tech it out's logic but I do think its a bad practice to teach a tech to ohm out a sequencer when performing a real life diagnosis.
    You're both correct as far as checking the operation in theory but in real life there are other variables to consider. A sequencer has a high rate of intermittent failures whether it be sticking closed or not opening. I would say the only time you would want to test a sequencer with an ohm meter would be if it was unsafe to access the terminals for testing with the power on.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  4. #30
    Quote Originally Posted by garyed View Post
    I can't argue with yours & tech it out's logic but I do think its a bad practice to teach a tech to ohm out a sequencer when performing a real life diagnosis.
    You're both correct as far as checking the operation in theory but in real life there are other variables to consider. A sequencer has a high rate of intermittent failures whether it be sticking closed or not opening. I would say the only time you would want to test a sequencer with an ohm meter would be if it was unsafe to access the terminals for testing with the power on.
    I agree it is Not the best way but it helped me understand the sequencer is all.

  5. #31
    Join Date
    Feb 2012
    Location
    Alabama
    Posts
    378
    Quote Originally Posted by garyed View Post
    I can't argue with yours & tech it out's logic but I do think its a bad practice to teach a tech to ohm out a sequencer when performing a real life diagnosis.
    You're both correct as far as checking the operation in theory but in real life there are other variables to consider. A sequencer has a high rate of intermittent failures whether it be sticking closed or not opening. I would say the only time you would want to test a sequencer with an ohm meter would be if it was unsafe to access the terminals for testing with the power on.
    Again someone need not reading enough of the thread to know what was previously posted. The ohm check was just if he wanted to make sure AFTER checking for voltage across the terminals of the sequencer. Although I am sure he is not even checking this thread anymore and neither am I after this.

    This thing has gone on and on over something as simple as a sequencer check. It has nothing to do with helping the OP anymore. There was nothing wrong with the explanation I gave on troubleshooting the sequencer, but if someone would like to they can start a whole new thread and explain how to properly do it. Please let this one DIE!

  6. #32
    Join Date
    Jan 2009
    Location
    Etters PA.
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    500
    amen

    Sent from my PC36100 using Tapatalk

  7. #33
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
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    14,914
    Let no dead horse go unbeaten!
    If more government is the answer, then it's a really stupid question.

  8. #34
    Join Date
    Jan 2010
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    6,318
    Quote Originally Posted by TACKERDOWN View Post
    amen

    Sent from my PC36100 using Tapatalk

  9. #35
    Join Date
    Jul 2009
    Location
    South Carolina
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    3,221
    Only 3 pages on how to test a sequencer.
    Is that all?
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

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