- What the MD-MHVACR Exam Actually Tests
- Eligibility: Confirming You Can Sit for the Exam
- The Six Exam Domains, Ranked by Priority
- Your Approved Reference Library
- Registration, Fees, and Retest Rules
- A Domain-Weighted Study Timeline
- Exam-Day Mechanics
- After You Pass: Licensing and Insurance
- Frequently Asked Questions
- You need 70% on 100 questions in 4 hours to pass - that's 70 correct answers, no more, no less.
- The exam is open-book, but only tabbed, highlighted, or underlined references are allowed - no handwritten notes.
- Refrigeration and Air Conditioning is the largest of the six domains, so study time should reflect that weight.
- A failed attempt means a 30-day wait for your first retest and 60 days for any retest after that.
What the MD-MHVACR Exam Actually Tests
The Maryland Master HVACR Contractor License Exam (MD-MHVACR) is administered by the Maryland Board of Heating, Ventilation, Air Conditioning and Refrigeration Contractors through PSI testing centers. It is a computer-delivered, open-book, multiple-choice exam with 100 questions and a 4-hour time limit. Passing requires a 70% score - a hard, unambiguous cutoff that every candidate needs to plan around from day one.
This is not a generic HVAC knowledge quiz. It's a licensing exam built around the specific skills a Master Contractor is expected to supervise: electrical systems, piping, refrigeration, heating, air distribution, and jobsite safety. If you're still confirming what this credential involves before diving into study mode, our overview article What Is MD-MHVACR? and the companion piece on MD-MHVACR Meaning lay out the full context in plain language.
Eligibility: Confirming You Can Sit for the Exam
Before you build a study plan, confirm you actually qualify to sit for the exam. Maryland requires applicants to have been licensed and regularly employed for at least three years as one of the following:
- Journeyman
- Limited Contractor
- Master Restricted Contractor
- HVACR instructor
In addition, applicants must have worked under the direction and control of a licensed Master Contractor, and must document at least 1,875 hours of HVACR services performed in the year immediately preceding the application. These are not soft guidelines - they are documentation requirements the Board will verify. For the full breakdown of qualifying pathways, see MD-MHVACR Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Key Takeaway
Gather your employment verification letters and hour logs before you schedule your exam date - eligibility paperwork issues are a far more common delay than exam difficulty itself.
The Six Exam Domains, Ranked by Priority
The MD-MHVACR exam is organized into six content domains. Understanding how these domains are weighted relative to each other is the single most useful thing you can do before opening a textbook, because it tells you where your study hours should actually go.
Domain 3: Refrigeration and Air Conditioning
This is the largest domain on the exam and should receive your heaviest study allocation. Candidates need fluency in refrigerant cycles, charging procedures, compressor and condenser troubleshooting, and system diagnostics as covered in Modern Refrigeration and Air Conditioning.
- Superheat/subcooling calculations under time pressure
- System diagnosis from symptom descriptions
- Cross-referencing Ductulator data with load calculations
Domain 1: Electrical Knowledge, Motors, and Controls
Expect scenario-based questions on motor types, control circuits, wiring diagrams, and troubleshooting logic rather than pure definitions.
- Single-phase vs. three-phase motor applications
- Control sequencing and safety switches
Domain 2: Piping
Piping questions draw heavily on the International Mechanical Code (2012 or 2018 edition), covering sizing, material selection, and installation practices.
- Refrigerant piping sizing and support requirements
- Code-referenced clearances and materials
Domain 4: Heating Systems
Covers combustion, venting, and heating equipment types - gas, oil, and electric - along with code-driven safety controls.
- Venting and combustion air requirements
- Heat exchanger and safety control troubleshooting
Domain 5: Air Distribution Systems
Duct design and airflow questions rely on Manual J calculations and Ductulator use - bring your slide rule skills, not just memorized formulas.
- Duct sizing with an ACCA Ductulator
- Airflow balancing and static pressure basics
Domain 6: Safety
Safety questions draw on OSHA 29 CFR Part 1926, focusing on jobsite hazard recognition and required protective procedures.
- Fall protection and confined space basics
- Refrigerant handling and PPE requirements
For a domain-by-domain deep dive with more worked examples, read MD-MHVACR Exam Domains 2026: Complete Guide to All 6 Content Areas. If you're still weighing how tough this exam is relative to your current experience level, How Hard Is the MD-MHVACR Exam? Complete Difficulty Guide 2026 walks through the honest answer.
Your Approved Reference Library
Because the exam is open-book, knowing exactly which references are allowed - and how you're permitted to mark them up - is a strategic advantage. Approved references include:
- 2012 or 2018 International Mechanical Code
- Modern Refrigeration and Air Conditioning, editions 19 through 21
- Manual J, 2006 eighth edition
- OSHA 29 CFR Part 1926
- ACCA Ductulator
You are permitted to permanently tab, highlight, and underline these references. You are not permitted to bring handwritten notes, loose papers, or study guides into the testing room. This means your prep work should focus on building tabbing systems and highlight patterns you can navigate instantly - not on writing cheat sheets you'll never be allowed to use.
Registration, Fees, and Retest Rules
The examination fee is $150, paid through PSI when you schedule your test. If you don't pass on your first attempt, Maryland requires a 30-day wait before you can request your first retest, and 60 days before any subsequent retest request. That means a failed attempt can cost you two months or more before you're back in the testing chair - a strong argument for treating your first attempt as the one that counts.
For a complete cost picture, including licensing fees beyond the exam itself, see MD-MHVACR Certification Cost 2026: Complete Pricing Breakdown. If you're mapping out when to schedule around work commitments and the required wait periods, MD-MHVACR Exam Dates 2026: Testing Windows, Deadlines & Scheduling covers the scheduling mechanics in detail.
| Item | Detail |
|---|---|
| Exam fee | $150 |
| Question count | 100 multiple-choice questions |
| Time limit | 4 hours |
| Passing score | 70% |
| First retest wait | 30 days |
| Subsequent retest wait | 60 days |
| Master license fee | $94.50 |
For the exact math behind the passing threshold - how many questions you can afford to miss - check MD-MHVACR Passing Score 2026: Exactly What You Need to Pass.
A Domain-Weighted Study Timeline
Rather than splitting study time evenly across six domains, allocate more weeks to Refrigeration and Air Conditioning given its size, and treat Safety and Piping as focused, shorter reviews since they lean heavily on specific reference documents (OSHA 1926 and the IMC, respectively) that reward familiarity over memorization.
Refrigeration and Air Conditioning foundations
- Review refrigerant cycle diagrams in Modern Refrigeration and Air Conditioning
- Practice superheat/subcooling problem sets
- Tab your code book by system type
Electrical, Motors, and Controls
- Drill motor wiring diagrams and control logic
- Practice scenario-based troubleshooting questions
Piping and Heating Systems
- Cross-reference IMC piping sizing tables
- Review combustion and venting requirements for heating equipment
Air Distribution, Safety, and full timed run-throughs
- Practice Ductulator sizing against Manual J scenarios
- Review OSHA 1926 highlights for jobsite safety
- Take a full 100-question, 4-hour timed practice session
Use spaced repetition for terminology-heavy material like code references and OSHA sections, but save your full timed practice runs for the final week so your pacing under the 4-hour clock is fresh going into exam day. If you want a compact, single-page reference for last-minute review, bookmark the MD-MHVACR Cheat Sheet 2026: One-Page Review of Must-Know Facts - just remember it's for your own study, not the testing room, since study guides are prohibited references.
Exam-Day Mechanics
You'll test at a PSI center on a computer-delivered format. Bring your approved, permanently tabbed references - Modern Refrigeration and Air Conditioning, the IMC, Manual J, OSHA 29 CFR Part 1926, and your Ductulator. Double-check that nothing in your materials contains handwritten notes or loose inserts, since that can disqualify a reference at check-in.
With 100 questions and 4 hours, pacing discipline matters. A practical approach: flag questions you're unsure of and move on rather than burning five minutes chasing one answer in your code book. Come back to flagged questions once you've secured the ones you know cold.
After You Pass: Licensing and Insurance
Passing the exam is one step toward the Master Contractor license. The current Master license fee is $94.50. Master Contractors subject to the insurance requirement must maintain $300,000 in general-liability insurance and $100,000 in property-damage insurance - budget for these before you assume you're finished once you pass the exam.
Maryland also maintains HVACR reciprocity with Delaware and Virginia, which can matter if you plan to take on work across state lines. For a broader look at whether the investment in time, fees, and insurance pays off across a career, read Is the MD-MHVACR Certification Worth It? Complete ROI Analysis 2026 and the related MD-MHVACR Salary Guide 2026: Complete Earnings Analysis. If you're curious about the range of employers and roles that value this license, MD-MHVACR Jobs covers common paths, and MD-MHVACR Training outlines how apprenticeship and instructor hours factor into eligibility.
Key Takeaway
Treat the exam fee, license fee, and insurance minimums as one combined budget line - passing the exam is necessary but not sufficient for operating as a licensed Master Contractor in Maryland.
For readers who landed here still sorting out terminology, our glossary-style pieces - What Does MD-MHVACR Stand For?, What Does MD-MHVACR Mean?, What Is A MD-MHVACR?, and What Is MD-MHVACR Certification? - are good starting points before returning to the study plan above. You can also review overall exam difficulty context in MD-MHVACR Pass Rate 2026: What the Data Shows and the general MD-MHVACR Certification overview, or head back to our practice test homepage to start a timed session today.
Frequently Asked Questions
The exam has 100 multiple-choice questions with a 4-hour time limit, delivered by computer at a PSI testing center.
No. While the exam is open-book, only approved references may be used, and they can be tabbed, highlighted, and underlined but cannot contain handwritten notes or loose papers. Study guides are not allowed as references.
You must wait 30 days before requesting your first retest. If you fail again, subsequent retest requests require a 60-day wait period.
Refrigeration and Air Conditioning is the largest domain on the exam, so it should receive the largest share of your study time relative to the other five domains.
Yes. Applicants need at least three years as a licensed Journeyman, Limited Contractor, Master Restricted Contractor, or HVACR instructor, work under a licensed Master Contractor's direction, and documentation of at least 1,875 HVACR service hours in the year before applying.