I just got an AC this morning for the first time ever. We're having a bit of a heat wave right now and I couldn't stand it any longer! That being said, the budgies have slept ALL DAY. Literally. I think they went for some food once. Should I be concerned? Do you think the the AC even related? They don't usually sleep this much.
As long as the budgies are not in the direct line of the air flow they should be fine. Keeping a constant and pleasant temperature is what needs to be done. hopefully all will be happy from the cooler temperature. Although Budgies can cope with high temperature's it is the humidity that causes problems.
If it has been extremely hot for a few days in a row their bodies will of been adjusted to the heat. then all of a sudden a drop in temperature sleeping is their bodies way of helping adjust perhaps I am purely guessing here I might add.