i have a rudd air handler and am trying to install the common wire coming from my thermostat. my wiring diagram doesnt have a common wire listed so i am not sure where to connect it. i attached the wiring diagram below. can any help me out? thank you.

air handler wiring diagram


The common wire for the thermostat should be connected to the 24V side of the transformer. In your schematic that you shared, this is the brown (br) wire leaving the transformer. There are 4 brown wires attached with a wire nut. This is where the COMmon for your thermostat should attach.

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  • could i add the common wire to the wire nut that says "TO OD UNIT" or does it have to be placed with the wire nut containing all of the brown wires? – john s Nov 27 '17 at 17:44
  • You can add the common wire to the wire nut that says "TO OD (Outdoor) unit" – cyclops Nov 27 '17 at 17:52

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