Time to add a little bleach and then flush some water down those cleanouts in your Central Air evaporator primary drain pipes. You don't want the pipe traps to crud up from whatever was left in them over the winter and overflow water into the secondary pan, or worse, onto the ceiling below.

The newer one don't need it anymore. Haven't been in my attic in five years.

So where does all the moisture that collects on the evaporator coils go? I've never seen any AC system that didn't have some type of water drain, at least not in a humid climate.

Perhaps you're confusing the primary and secondary drains. I could see where some might eliminate a secondary or safety pan and drain that catches overflow or water that begins to leak from an older system. Unless I'm missing something, any AC system running in a humid climate is going to need to drain the moisture that condenses and drips off the evaporator coils.

My newer primary drain does what it's supposed to do. I drains into my shower drain.

That's what they all do before they age and start leaking Bill. The primary drains on each of my two units drain into the piping for the upstairs sink. The problem comes into play once the primary pans get old and rusty (since they hold water) and begin to leak. They can also overflow if the drain piping gets clogged up. In both cases, the secondary pan that sits under the unit catches the leaking or overflow water and carries it outside via piping that usually exits under one of the roof soffets. I've seen cases where neighbors have let their secondary pans drain the water from their old, leaking units for seasons on end.

IMO, every AC evaporator inside a home should be treated just like any water heater tank and have a pan under it to catch water once it begins to leak sometime down the road.

Bleach and water or vinegar? AC guy told me vinegar but I have always thought bleach.

We use a cup of bleach and chase it with water....

Thanks for the reminder. We had a drain in the attic that clogged and made a mess of the ceiling and walls in our bathroom below.