Best free resources for 313D prep in 2026 — compiled list
I've been compiling resources as I study for my 313D - Residential Air Conditioning Systems Mechanic Certification certification and figured I'd share what I've found. All free unless noted.
Practice Tests:
- PracticeTestGeeks — most comprehensive collection I've found, good question explanations, covers 313D - Residential Air Conditioning Systems Mechanic Certification, Air Conditioning Repair, and ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers Certification. Free.
- Official practice materials from the certifying body — usually 1 free sample exam, worth doing even though it's short
Study Materials:
- The official 313D exam handbook / candidate guide (PDF, free from the certifying body's website)
- YouTube — search for "313D exam prep" — there are surprisingly good free video reviews for most hvac certifications
- Reddit r/certifications — people post their exam experiences and tips regularly
Paid (worth it if budget allows):
- Official study guides run $30-80 for most hvac certifications — worth it if your exam has lots of specific factual content
- Some certifying bodies offer prep courses — check if your employer covers it (many do for required certifications)
What resources have others found useful for hvac exams? I'll add them to this list.
Great list. I'd add: LinkedIn Learning has some hvac-related courses that overlap with cert content, and if you have a library card many libraries give free access to it. Also check if your local library has access to O'Reilly or similar — tons of technical content there.
The official candidate guide is something a lot of people skip but it literally tells you the topic weighting and domain breakdown. It's the roadmap for your study plan. Never skip it.
For 313D - Residential Air Conditioning Systems Mechanic Certification specifically, I found the PracticeTestGeeks explanations were detailed enough that I didn't need to buy a separate study guide. The combination of doing the practice questions + reading every explanation (for both right and wrong answers) covered most of the content I needed.