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Thread: Outside ac unit not kicking on

  1. #1

    Default Outside ac unit not kicking on

    The outside unit of my house it currently not working. I've checked all the breakers and none are tripped. The inside blower kicks on and the contractor in the unit it pushed in and a it makes a hum noise, I've just installed a new capacitor because that's what I thought was the problem but the new capacitor did not fix it.

    Any ideas ? Thanks all!

  2. #2
    Join Date
    Feb 2012
    Lala land, OH


    (for future reference, please only post to the forum once so replies do your posts do not get crossed...thanks)

    The condenser unit has a separate breaker from your indoor unit. Double check that you didnt miss it. Turn that breaker off and on even if it looks ok. Sometimes a tripped breaker looks ok.

    Check your in-sight disconnect.. They sometimes have fuses inside them. Make sure it's set to on. Someone may have been playing in the box.

    What voltage do you have at your contactor? You should have about 240V (+/-) from 1 input terminal to the other and 120V (+/-) from each contact to ground (or clean metal on the frame of the condenser unit). When the contactor is pulled in you should see close to the same voltages when you check the other side. Test from output terminal to output terminal, not input to output.

    Your contactor is powered by the indoor unit, it will function without power to the condenser unit. If the fan and the compressor both are not running, there's a good chance theres no power getting into the unit. You need both 120V legs for anything to function.

  3. #3


    I've flipped the outside breaker a few times , I'm no professional so it might take me a bit to figure this out. I don't have a voltage meter so I guess that is the next step unless some one has any other things I can check while I figure out the voltage

    is the in-sight disconnect the big breaker outside the house with the handle?
    Last edited by Damienqwerty; 08-18-2015 at 12:38 AM.

  4. #4
    Join Date
    Feb 2012
    Lala land, OH


    It is the box behind your AC that is used to disconnect power while it is being worked on. There are sometimes fuses in it behind a cover. (turn off the breaker and verify power is off before attempting to remove the fuses). You will need a meter to be able to test the fuses. Sometimes a oldschool hardware store will test them for you. Same with a electrical supply place. Most big box stores will just tell you to buy another pair of fuses and try it (save your money).

    Other then that there is not much else you can do on your own without test equipment and electrical knowledge.

  5. #5


    I would suggest turning your thermostat to off and then reset your air conditioner’s circuit breaker because it normally happens due to low voltage issue.

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