Thanks to everyone that gave comments on this. For me, the good news is that my air conditioners were both installed in 2024 and I am trying to get to the correct tax answer for the 2024 return. I suppose it is possible that the IRS will clarify the instructions for 2024 and possibly revise Form 5695. If not, I think the safe option is to file the 2024 return on TurboTax with a $600 credit and, if the IRS changes this treatment within 3 years, file an amended return to get the additional $600.
