I recently bought an Ecobee thermostat and it’s needing a c wire to be connected. Upon looking through the wires from the thermostat there was a blue wire tucked away in the wall. When I looked inside the a/c unit this blue wire is not connected to anything. I have a Rhemm rhll-hm3821ja model. I want to assume that this is the common wire. I’m unsure of what to do at this point or what to connect it to if possible. It looks like there’s a brown wire connected to the c terminal on the control panel that is then connected to a black wire. That’s where I’m confused. Any help would be greatly appreciated.