Is it common to have the blue and yellow wire both connected to the Y terminal in the thermostat? I went under the house and looked at the HVAC unit and it looks like blue is connected to C out of the unit (along with purple). It seems like the blue wire is my C but I want to be confident. enter image description hereenter image description hereenter image description here

  • Added photos of the unit. Notice that the tan box with the dial/switch is labeled "C" – Ross Hambrick Jun 10 '17 at 19:53
  • I don't think you're looking at the same blue wire in the furnace. Look for where the thermostat cable comes in and trace it from there. – Tyson Jun 12 '17 at 0:16

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