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  1. #1
    Join Date
    Jun 2002
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    south jersey
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    1,139

    Capacitor question

    Let me start by saying sorry for the lack of information. That aside, I had a no cooling call and found a dual capacitor on a Bryant 3 ton condenser(about 10 years old)35/5 440 volt with the 5mf side for the condenser side bad. Put in temporary 5mf and left the compressor hooked to the 35mf of the old one. Went to United a picked up a new one. They did not have a round one ,only oval.Guy said same thing no problem. I hook up new capacitor and fan works great but no compressor. I did check capacitance of new capacitor and it was fine. Did I get a start instead of a run or vice versa? Could the original capacitor been both start and run? Why does the fan work but not the compressor? Any help is appreciated.
    You need to put the phone down and get back to work!

  2. #2
    Join Date
    Jul 2007
    Location
    Virginia
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    5,935
    Quote Originally Posted by jnsrose View Post
    Did I get a start instead of a run or vice versa? Could the original capacitor been both start and run? Why does the fan work but not the compressor? Any help is appreciated.
    1. I don't recall any start caps that are oval in shape - so it was a run cap.

    2. They do not make caps that are Start/Run caps.

    3. Start caps have bleed resistors on them.

    4. I'm saying this from experience - are you sure you didn't accidentaly reverse the Fan and Herm leads?

    5. I would double check all the wiring.

    6. Just because the cap tested good out of the box, it might be bad under a load. Test and use this formula while unit is running. - 2652 x Start winding amp / voltage across the C-Herm terminals = Cap MFD.
    Instead of learning the tricks of the trade, learn the trade.

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    5,062
    Quote Originally Posted by jnsrose View Post
    Let me start by saying sorry for the lack of information. That aside, I had a no cooling call and found a dual capacitor on a Bryant 3 ton condenser(about 10 years old)35/5 440 volt with the 5mf side for the condenser side bad. Put in temporary 5mf and left the compressor hooked to the 35mf of the old one. Went to United a picked up a new one. They did not have a round one ,only oval.Guy said same thing no problem. I hook up new capacitor and fan works great but no compressor. I did check capacitance of new capacitor and it was fine. Did I get a start instead of a run or vice versa? Could the original capacitor been both start and run? Why does the fan work but not the compressor? Any help is appreciated.
    Possibly you wired new one wrong. The difference between a start and run capacitor, look totally different.

  4. #4
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Well the temp fix was good.

    If you installed a new cap with the same values as the old dual run cap, and the compressor won't run, there are two possibilities:

    1) There is a wiring goof that was made during the replacement, or

    2) There is a problem with the new cap, and it should be replaced.
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    2 Tim 3:16-17

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  5. #5
    Join Date
    May 2009
    Location
    Baltimore, Md
    Posts
    34
    Your post does lack info. Why did you check capacitor in the first place? No fan no compressor? the 35/5 is a start run combo 35 being the start and 5 being the run. If I come across a dual thats bad then to me the whole thing is bad or soon will be. Get an exact replacement or two new ones, find out more exactly how they are wired. Also if comp isn't running and you think it should, check the windings.

  6. #6
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Quote Originally Posted by coldmark View Post
    Your post does lack info. Why did you check capacitor in the first place? No fan no compressor? the 35/5 is a start run combo 35 being the start and 5 being the run. If I come across a dual thats bad then to me the whole thing is bad or soon will be. Get an exact replacement or two new ones, find out more exactly how they are wired. Also if comp isn't running and you think it should, check the windings.
    Actually, the 35 and the 5 are run capacitors, in the same package. The statement in bold type above is incorrect.

    He (the OP) made a temp repair and then went to the supply house for a new 35/5. The only difference was the shape of the package.

    He probably got a bad one, or there is a wire in the wrong spot.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  7. #7
    Join Date
    Jul 2007
    Location
    Virginia
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    Quote Originally Posted by coldmark View Post
    the 35/5 is a start run combo 35 being the start and 5 being the run.
    Where did you learn this?

    Please explain how this works.
    Instead of learning the tricks of the trade, learn the trade.

  8. #8
    Join Date
    May 2009
    Location
    Baltimore, Md
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    34
    More capacitance is needed to get motor spinning from a stop, potential relay removes start capacitance and run value remains for operation, thats why they call them dual they have start and run in one can, am I wrong?

  9. #9
    Join Date
    Nov 2005
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    Scary posts.

  10. #10
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    Quote Originally Posted by coldmark View Post
    More capacitance is needed to get motor spinning from a stop, potential relay removes start capacitance and run value remains for operation, thats why they call them dual they have start and run in one can, am I wrong?
    Yes but its a creative explanation.

    They are both run, one being for the comp and the other for the fan mptor.

  11. #11
    Join Date
    May 2009
    Location
    Baltimore, Md
    Posts
    34
    Scary means I'm wrong, I guess. Actually I have never seen a start capacitor with a mf value under a hundred so you are absolutly correct i am sorry for the bad info its a dual run.

  12. #12
    Join Date
    Jun 2002
    Location
    south jersey
    Posts
    1,139
    Thanks for all the info. I double checked wiring and was ok. As Time builder stated the capacitor I installed was suppose to be suitable replacement just a different shape. I did not check capacitance while unit was running.(did not know you could) I did wind up replacing it with an exact replacement was just curious why this one did not run the compressor. Sounds more like the capacitor was bad. I will have to dig it from the truck and do further testing. Was curious about the dual run/start thing though. Thanks again guys. Rundawg I will definitely try that formula on the next one I come across.
    You need to put the phone down and get back to work!

  13. #13
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    155
    Both caps are run caps. Each should be wired in series with the respective motors start winding. The smaller value for the condenser fan and the larger for the compressor. If you look a bit deeper you likely will find a START cap for the compressor. It generally is cylindrical, black and plastic. mfd rating will be in the hundreds.

    What the start caps do is shift the phase angle of the current with respect to the voltage so we have in effect two slightly out of phase windings (start and run) that improve the efficiency and running torque of the motor.

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