There will be no depreciation shown on your 2023 taxes, for the 2024 tax year. Only for the 2023 tax year beginning with the date placed in service. Most likely, you're misunderstanding the screens (of which some are not clear) on the information being asked for when you enter the HVAC in the assets/depreciation section.
Classified as residential rental real estate, which as you know is 27.5 years to depreciate
Date placed in service is the date it became operational
Business use percentage is 100%
Cost is what you paid for it, including shipping, installation, and any other expenses related to the HVAC.
Cost of Land is $0.
The program will use the MM/SL convention and depreciation will start from the 15th of whatever month it was placed in service.
Note that the 1st year depreciation will be lower than the years that follow, since it was not in service for all 365 days of the tax year.
TO check the math, see IRS Pub 946 at https://www.irs.gov/pub/irs-pdf/p946.pdf and use the MACRS worksheet on page 36. For line 6 of that worksheet, use table A-6 on page 71.
