If someone is too cold from an air conditioner, can someone have a toddler turn it off on Shabbat or Yom tov? Can someone have a toddler turn off a light for someone on Shabbat or Yom tov??

Shalom, My Rabbi and teacher, Rav Shlomo Aviner shlitah, addresses your question in his book "Torat Imacha" (hebrew – p. 249). Here is a translation of his answer:- "It is clear that in general one is not allowed to tell a child to do forbidden labor on Shabbat. The opposite is true – one must instruct them to keep Shabbat. However, sometimes there is no other option, and we have no choice but to enlist the help of a child. Even though this involves a serious educational dilemma, in times of great need we are allowed to rely upon the ruling of the Shulchan Aruch of the the Rav (the Ba'al HaTanya – Orach Haim 343, 6-8) who allows one to instruct a child to perform a Rabbinically forbidden act, on the condition that this happens only occasionally and not regularly. This is because the major educational damage occurs when the child becomes accustomed to breaking Shabbat, but not from a one time occurrence. One should try to use the youngest child they can find, and if they are so young as to have no understanding of Shabbat at all, that is all the better, as long as they can do what is needed. It is also better to use a child who is not your own (with the agreement of the child's parents), because the educational obligations to one's own children is greater than to others. Turning off lights is generally only a rabbinic prohibition. In summary – in a time of great need, infrequency, one may ask a small child to perform a Rabbinically forbidden act on Shabbat". To this I can add that turning off an air-conditioner is also usually only a Rabbinic prohibition. Blessings.