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I recently received a wifi enabled thermostat which I thought I could install easily since I saw an unused wire (Blue) which I assumed would be the C wire behind the current thermostat.
When I went to install it, I found out the blue wire isn't actually connected to anything but there is a red wire connected the C terminal which I believe runs out to the ac unit.
Can I just connect the blue wire to the C terminal in addition to leaving the red wire or will this short something? Or does this just need to be completely rewired?