So I'm looking for some help in identifying where I can attach a C/Common Wire to my HVAC system, but unfortunately my system doesn't have a control board that I can easily attach a powerkit to. For reference I'm planning to install an Echobee3.
I've uploaded some photos here: http://imgur.com/gallery/LPzoq/
Any advice would be greatly appreciated, probably adding some circle/arrows so I know what you're talking about ;)
After looking at Tester101's answer, here's an annotated picture. Notice how they're two free wires(red and black)