This is the main reason why I’m considering AC. We get decent canyon breeze, so, on average summer day, we’re OK. It’s only bad when we get a Santa Ana, where even the breeze is hot.
If it cost $2-3k more to add AC and I get to amortize it over 20 years, that’s $100/year. I think that’s totally worth it.
Our current heater is also ~20 years old, but because of the tax credit and these program, it’s totally worth it to get the best stuff and get it soon.