Two stories, one system, and an attic full of flex duct
Heat rises, the second floor gains heat straight through the roof, and the equipment that is supposed to fix that sits in the hottest space in the house. Flex duct in a large attic runs long, and long flex duct sags, kinks and gets stepped on. A duct with a sharp bend in it delivers a fraction of the air it was designed to deliver, and the bedrooms furthest from the air handler get the least of what is left.
Some homes here were built with two systems and some with one system and a zone damper board. They fail in different ways. A stuck zone damper looks exactly like a dead air conditioner from the homeowner side, which is why a technician should confirm what kind of setup you have before quoting anything.
Neighborhoods here age in waves
When a subdivision goes up over two or three years, the equipment inside it goes in over the same two or three years, and it tends to reach the end of its service life around the same time. If several of your neighbors have replaced systems recently, yours is probably in the same range. That is not a sales line, it is just how the timing works out.
The practical takeaway is to have your system looked at before the first genuinely hot week, not during it. A weak capacitor or a slow refrigerant leak is a scheduled appointment in April and an emergency in July.
Attic equipment means water lives above your ceiling
An attic air handler drains through a primary line, and it sits in a secondary pan with a float switch as a backup. When that float switch shuts your system down on a hot afternoon, the switch is doing exactly what it was installed to do. It is telling you the primary drain is not draining.
Do not bypass the switch to get cooling back. Clearing the line is a small job. Replacing drywall, insulation and a ceiling is not.