I am trying to add a fan in a bathroom and need some wiring assistance. I removed the switch thet controls the overhead light and found 2 black wires attached. From the research I have done it seems this is correct: one hot black from the main box and the black going to the light, and then the white wires should be connected to complete the circuit. MY issue is that I don't know where the white wires are even after removing drywall and following the black wires almost to the ceiling. Is there a way to add the fan using the same hot wire as the light without connecting the fan's white wire to the main box and light white wires? Below is the wiring diagram I am trying to follow.
You know the light works so the light has to have the hot for it black in your drawing and the white. Your fan will need a new cable run from the red , white and ground in the light over to the fan and your system will work if your schematic is correct. This is how I used to wire bathrooms with windows that I did not put a fan in, got lots of jobs to do just what you are doing.