I think that the temperature is fine, but I would be worried about a draft from the window. I don't use the cool down method but I think that most breeders lower the temperature of their hot spot not the ambient temp. I would keep the ambient temp around 72 and just lower the hot area from 90ish down to 80ish.
If I'm wrong someone please step in, I usually don't speak unless I'm sure but I'm interested to see if I understand myself.