re: Easiest way to keep A/C drip pan from filling up?

Get your drain pipe clean.

Don't just pour bleach if it's clogged as it can damage the pvc if it just sits. You can use vinegar but if it's clogged it won't likely fix it. Use a shop vac to suck out the water from the pan and then use it to blow air through the drain pipe.

I had this problem last week. After doing all of this, I was still having water back up so I called my AC guy. He used a co2 cartridge to clean the line and was there for like 5 minutes. Cost me $20.