Best free HVAC/R tools
Free tools we checked on Oct 18, 2026. We don't make or sponsor any of them, and there are no affiliate links here.
The manufacturer's charging chart always controls. Use these to check your math, not to override the equipment's instructions.
ToolGrit Superheat & Subcooling Calculator
Best for: Actual superheat and subcooling from your gauge readings for eight common refrigerants, with PDF/CSV export. Free. The page carries affiliate gear links.R-Pro free field tools
Best for: A pressure/saturation-temperature chart for 34 refrigerants and 60+ troubleshooting guides; free, no sign-up, works offline once loaded.ESCO Institute free 608 practice exams
Best for: Core, Type I, II and III practice tests (English and Spanish), plus free R-410A, A3 and A2L/A3 safety practice checks. Practice questions, not the real exam.Kelvin training
Best for: Practice questions with fully worked answers on saturation, superheat and subcooling (one example is worked on R-454B). Practice module, calculator and P-T charts are free; written for Australian refrigeration courses, but the physics is the same.
Best for: Actual superheat and subcooling from your gauge readings for eight common refrigerants, with PDF/CSV export. Free. The page carries affiliate gear links.R-Pro free field tools
Best for: A pressure/saturation-temperature chart for 34 refrigerants and 60+ troubleshooting guides; free, no sign-up, works offline once loaded.ESCO Institute free 608 practice exams
Best for: Core, Type I, II and III practice tests (English and Spanish), plus free R-410A, A3 and A2L/A3 safety practice checks. Practice questions, not the real exam.Kelvin training
Best for: Practice questions with fully worked answers on saturation, superheat and subcooling (one example is worked on R-454B). Practice module, calculator and P-T charts are free; written for Australian refrigeration courses, but the physics is the same.
Official references
- EPA SNAP list: a refrigerant's GWP, ASHRAE safety class and new/retrofit listing.
- EPA-approved 608 certifying programs
- AHRI A2L building code map
Descriptions are from each site's own page. ESCO's page was read with a fetch tool because it blocks simple scripts.