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  1. #1

    Confused A/C contactor issue!! Need Help

    A/C compressor/fan will not turn on.

    Here's the confusing part:
    - When main power is turned off, but control voltage is on, the contactor energizes and engages the contacts.
    - As soon as the main power is turned on, the contactor disengages and will not send power to compressor/fan.
    - If I manually engage the contactor, the compressor/fan turns on.
    - I am consistantly getting about 27 volts at the control voltage side of contactor whether or not the main power is turned on.

    Any ideas?
    Is there an overload switch that is disengaging the contactor?

  2. #2
    Join Date
    Sep 2002
    Location
    Northeast Ohio
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    4,803
    I'm sorry, the rules on site don't allow for specfic DIY instructions. Any competant HVAC tech will be able to fix you up.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  3. #3
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,642
    do you have a utility company load shedding box on the outdoor unit?

    when line voltage is applied the contactor will drop out for a 5-10 minute time delay.

  4. #4
    Quote Originally Posted by heaterman View Post
    I'm sorry, the rules on site don't allow for specfic DIY instructions. Any competant HVAC tech will be able to fix you up.
    I am not asking for DIY instructions. I am asking for a "professional opinion", which what this board is correct, "Ask a Professional." I am asking if the contactor is bad, possibly a short leading to the contactor, or if there is an overload switch that would apply in this situation. It doesn't seem that an overload switch would apply because I am consistantly getting about 27 volts on the control side of the contactor in all test situations.

  5. #5
    Quote Originally Posted by t527ed View Post
    do you have a utility company load shedding box on the outdoor unit?

    when line voltage is applied the contactor will drop out for a 5-10 minute time delay.
    Yes there is, but it doesn't cut off the power, as I can manually depress the contactor and the fan/compressor turn on.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,817
    Your asking for DIY diagnostic advise. Which isn't permitted here.
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    How many times must one fix something before it is fixed?

  7. #7
    Quote Originally Posted by beenthere View Post
    Your asking for DIY diagnostic advise. Which isn't permitted here.
    So what's the point of this site?
    Would it be OK to ask what an air conditioner does? Does it heat or cool the home? That's about the extent of "professional advice" that you guys give out?

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,817
    Read some of the other threads in the AOP. You see that we help many people, without going into DIY.
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    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    11,087
    Quote Originally Posted by tpedersen1 View Post
    Yes there is, but it doesn't cut off the power, as I can manually depress the contactor and the fan/compressor turn on.
    Look on the side of the utility's box. It should say it has some kind of time delay. Put all the covers back on with the power off and then turn the power on. Wait five or more minutes. Unit should come on. If it is really hot out, you may have to wait longer. It's a load shedding device for the utility, after all.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  10. #10
    Quote Originally Posted by Shophound View Post
    Look on the side of the utility's box. It should say it has some kind of time delay. Put all the covers back on with the power off and then turn the power on. Wait five or more minutes. Unit should come on. If it is really hot out, you may have to wait longer. It's a load shedding device for the utility, after all.
    Thank you so much for the professional response. That is exactly what it was! The voltage going in to the load shedding device was 27 v. and nothing coming out. Bypassed it and it works great. Going to call the electric company tomorrow.

    Thanks again so much!

  11. #11
    Join Date
    Jan 2004
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    Lancaster PA
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    66,817
    Quote Originally Posted by tpedersen1 View Post
    Thank you so much for the professional response. That is exactly what it was! The voltage going in to the load shedding device was 27 v. and nothing coming out. Bypassed it and it works great. Going to call the electric company tomorrow.

    Thanks again so much!
    I believe that is basically the same answer you got in this post.
    http://hvac-talk.com/vbb/showthread....1#post16236511
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    How many times must one fix something before it is fixed?

  12. #12
    You're right, it is. I just wasn't at the unit to test it at the time. The only reason I thought it wasn't us because it doesn't come on at all after the initial drop in power. Did some testing on the load shedding device and turns out that there was a short in the incoming 220 v line to the 24 v load shedding line. Assuming the load shedding device is blown. Gonna have the electric company come check it out.

  13. #13
    Join Date
    Sep 2002
    Location
    Northeast Ohio
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    I also believe that you DID use the advice given to particpate in DIY
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


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