Honda 3000 generator

I don't have a 3000, but I used to run a 13,500 with a 2000. There should be no reason a 3000 wouldn't handle a 15,000 with power to spare. I wouldn't expect to run the microwave, coffee maker and electric water heater along with the AC, but it should run the AC fine.

I currently run two 15,000 units along with just about anything else I want to at the same time with an Onan 5500 generator so even splitting that in half you should only need less than 2750 watts for a single AC unit and modest other items.