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Problem: How do I wire up a dual round capacitor?

troubleshooting air conditioners and heat pumps

Problem: I forgot how to wire up the dual round capacitor that I purchased from you. How do I go about wiring it up so it doesn’t blow the capacitor up again?


Answer: Thanks for your interest in our web site! You would need to look at the wiring diagram that came with the unit. Usually the wiring diagram is glued to one of the panels on the air conditioner. Hope you can read it. Round dual capacitors on the top should be marked: Herm, Com and Fan. Rule of thumb on wiring the capacitor is: Herm on capacitor goes to the start winding on the compressor, Fan on capacitor goes to brown fan wire that goes to the fan, and Com on the capacitor comes off one leg of the contactor to provide power to the capacitor. There are usually more than one wire connected to the Com terminal. The Com terminal is used so other components like the fan motor of the air conditioner can steal power off the Com connection. Below we have two YouTube Videos that explain how to troubleshoot Air conditioner and heat pump capacitors. If you have any questions please email us anytime: support@arnoldservice.com. God bless you and your family today and always. Sincerely, Steve Arnold

6 thoughts on “Problem: How do I wire up a dual round capacitor?

  1. My AC Capacitor has two wires, one to the Compressor, and the other to the common terminal. No wire to the Fan terminal, is this correct?

    1. This would be correct only if your condenser fan motor does not use a capacitor or if someone install a separate individual capacitor for the fan motor. They could have the dual capacitor wired to only power the compressor. I have seen this before when a new fan motor is installed or if the contractor does not have the correct capacitor for both the fan motor and compressor on the truck. Thanks for asking this question. Steve

      1. Thank You for sharing your knowledge.

      2. Thank you so very much for your kind words! Hope these posts will help people troubleshoot and fix their heating and air conditioners.

  2. Terminal connection

    1. I really do not know what your question is exactly. The terminal connections on top of the capacitor should be marked: Herm, Com and Fan. If you have any other questions please let me know. Steve

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