Hi folks, I have an issue that's been troubling me for several weeks. I have 1 ac unit that keeps getting water in the secondary drain line and activates the overflow switch thus shutting off the unit. I take the switch out, twist the pipe and drain the water into a plastic bucket. If I leave the switch out and the part that the switch fits in pointed down, the unit works normally. The water goes into the main drain and thus the pump that pumps the water outside. The bucket stays dry (no water draining from the secondary line). When I put the switch back in and turn it facing up, the secondary drain fills again but not the primary. Any idea what's going on? Thanks! Greg

By the way, I usually don't have that float switch hanging down, I have it resting on the bottom of the pan, away from any water.

 

Pretty strange problem. The only thing I can think of is that the air handler is running in a heavy vacuum. Have you tried changing the filter ?