I'm trying to add a fan/light combo switch to a bedroom that already had a switch that controlled a recepticle. There was a single 14/3 wire for the existing switch. I've added another 14/3 for the combo switch. So....how do I do this? Many thanks!
I note that (strangely) you have not had any response to your request in almost 24 hours.
While I am NOT a "local", I will attempt a response to your question.
(I am sure that, if I get anything wrong, I will be corrected - soon enough!)
Although you have not said so, presumably, you have ALSO installed a Fan/Light combo in the room concerned and the new 14/3 cable "goes" to it !
(The following assumes that the original incoming White wire is a "Neutral" wire [and, originally, was not connected to anything],
the original incoming Black wire is a "Line" wire [Live] and
the original Red incoming wire is a "Switched-Line" wire back to the switched-outlet.
This should be checked at the switched-outlet.
However, from the second photo, it appears that there MAY be an additional incoming White wire ???)
Undo the the two Red wires, the Red pigtale and the Yellow wire from the new switch unit - which you have joined together.
Join together both the White wires (Neutrals) - original incoming and new outgoing.
Join the incoming original Black wire (Line) to the Black pigtail which you now have on the original switch and to the Black wire from the new switch unit.
Restore the original incoming Red wire to the other terminal of the original switch. (The pigtail and a connector should NOT be required.)
Connect the new outgoing Red wire to the Red wire from the new switch unit.
Connect the new outgoing Black wire to the Yellow wire from the new switch unit.
At the other end of the new 14/3 cable
connect the new outgoing Red wire to the "Line" terminal of the Light,
connect the new outgoing Black wire to the "Line" terminal of the Fan and
connect the White Neutral wire to the "Neutral" terminal of the Light/Fan Combination.