Why do we need elbows for the ac condensation line? We are having trouble with the water not wanting to go down. We have flushed the line, blown air through the line, and we can't seem to find out if there is a blockage or what? We watched the water flow through the cleanout and it looked like it was flowing fine but the water keeps over flowing from the condensation line.

Perhaps the condensation pan is not sitting level and the water overflows an edge before it reaches the level of the drain tube.

I agree with Harold but am wondering why you are asking about why elbows are needed. You can have as many elbows in a condensate line as needed as long as they all have a 1/4 slope