Compared to the 2019 edition, major updates include:
If you still want to search online, use these safe practices: 2023+ashrae+handbook+hvac+applications+pdf+free+updated
Many universities subscribe to the ASHRAE Handbook Online through their library portal. If you’re a student or faculty member, check your library’s database subscriptions. You can often download chapters as PDFs for personal use. Compared to the 2019 edition, major updates include:
ASHRAE releases preview editions of selected chapters for public comment. Also, the 2015 and 2019 handbooks are sometimes available legally through the Internet Archive or Google Books for in-library borrowing. While not the “updated” 2023 version, they cover ~80% of core applications. Many universities subscribe to the ASHRAE Handbook Online
Even if you find a "free PDF" claiming to be the 2023 edition: