re: A/C condensate pan overflow

Fwiw, float switches aren’t guarantees or even close to it to stop leaks. They mostly just slow them down considerably for the resident to notice the issue and resolve it. Have had multiple overflows/ leaks in rental units with float switches activated but tenants being idiots. “I was wondering why the thermostat kept turning off!”

All the float switch does is when it’s filled with water the switch floats and cuts power to the thermostat. What happens often is the water will slowly drain, float switch lowers, and ac kicks back on, and more condensate is produced and causes an overflow/ leak again.

I’ve DIY pumps that are only $30-40 and it’s extremely easy and cheap to do. Highly recommend for 2nd floor units or anywhere a small leak would an issue. You simply add 2 Ts or Ys in your drain line. When the drain line stops up the water backs up to the T and flows into the pump. The pump kicks on and pumps the water out. The pump is not quiet so when you hear it, you know you have a drain line blockage.

ETA: This is what I'm talking about OP. Again, basic plumping and PVC skills and an outlet and this is a fantastic back up IMO for under $50 for any AC systems not on the ground floor. Works great along with a Float switch, I don't know why they aren't installed more often.