I agree with the others - air conditioning is fine but most Yorkies will like a blanket or t-shirt or something to keep them from getting too cold.
I just wanted to say welcome to YT! If your baby is not great with other dogs, it might be a good idea to start socializing her - perhaps a training class or something. Get her used to being around other dogs and see if she changes. Then, if she seems to get more used to being around other pups, you could look for her a brother or sister. Perhaps take her along when looking and see if she connects to one
