I recently installed a new ecobee3 lite. When I completed the setup process, I found that there was no option to enable cooling. My original setup had both heat and cool options. I believe the option is missing because I connected the Y wire to C, which is what my schematic suggested. Right now, I have:
R wire -> ecobee Rc and Rh via jumper
W wire -> ecobee W terminal
G wire -> ecobee G terminal
Y wire -> ecobee C terminal
Is there any way I can get the option to enable cool back? There are 2 extra unused wires that run from the thermostat to the HVAC system in the below diagram. I was thinking about using one of them and connecting it to the BRN wire between the transformer and the left COM port, and wiring the Y wire to the ecobee Y port, would that work?
The photos are my old thermostat, new ecobee, and my HVAC system diagram.
The last picture is the wiring. The top left contains the connections to the thermostat, and the wires running downward on the left are the contractor seen in the system diagram connected to Y.