- MD-MHVACR is the Maryland Master HVACR Contractor License Exam, administered through PSI for the state board.
- The exam has 100 questions, a 4-hour limit, and requires a 70% passing score.
- It is open-book, but only specific approved references are allowed - study guides are not.
- Candidates need three years of qualifying experience and 1,875 documented HVACR service hours in the prior year.
What Is A MD-MHVACR, Exactly?
MD-MHVACR stands for the Maryland Master HVACR Contractor License Exam, the state licensing test that qualified heating, ventilation, air conditioning, and refrigeration professionals must pass to legally operate as a Master HVACR Contractor in Maryland. This is not a manufacturer certification or a general industry credential - it is a state-issued license exam tied directly to Maryland's contractor licensing law, and passing it is the gateway to running or supervising HVACR work under a Master license in the state.
If you're researching whether this exam applies to you, it's worth reading a companion breakdown at What Is MD-MHVACR?, which covers the same core definition from a slightly different angle, or the shorter explainer at MD-MHVACR Meaning if you just need the acronym unpacked quickly.
Who Administers the Exam
The Maryland Board of Heating, Ventilation, Air Conditioning and Refrigeration Contractors oversees licensure for HVACR trades in the state, and it contracts with PSI to deliver the actual examination. PSI runs the computer-based testing centers where candidates sit for the exam, handles scheduling, and reports results, but the underlying license requirements, exam content outline, and approval of candidates come from the state board itself.
This distinction matters because candidates sometimes confuse the testing vendor with the licensing authority. When you're checking eligibility, submitting documentation, or asking about renewal, you're dealing with the Maryland board. When you're scheduling your seat or asking about testing-center policies, you're dealing with PSI.
Who Can Sit for the Exam
Maryland doesn't let just anyone register for the Master HVACR exam. Candidates must meet a specific experience threshold before they're eligible to apply:
- At least three years licensed and regularly employed as a Journeyman, Limited Contractor, Master Restricted Contractor, or HVACR instructor
- Work performed under the direction and control of a licensed Master Contractor
- Documentation of at least 1,875 hours of HVACR services in the year immediately preceding application
These aren't loose guidelines - the board expects documented proof, so candidates typically need employer verification, pay records, or job logs to support their application. For a full walkthrough of exactly what paperwork and timelines are involved, see MD-MHVACR Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Key Takeaway
Don't wait until you've submitted your application to start gathering hour documentation. Begin tracking your 1,875 hours and employer verification as early as possible, since incomplete paperwork is one of the most common reasons applications stall.
Exam Format and Fees
The MD-MHVACR exam is delivered as a computer-based, open-book, multiple-choice test with the following structure:
- 100 questions total
- 4-hour time limit
- 70% required to pass
- $150 examination fee
Because it's open-book, the exam rewards candidates who know where to find information quickly in their approved references almost as much as candidates who have facts memorized. That said, 100 questions in 4 hours doesn't leave time to look up every answer - you still need working knowledge of core HVACR concepts to move efficiently. For a deeper look at how demanding this pacing actually is in practice, check out How Hard Is the MD-MHVACR Exam? Complete Difficulty Guide 2026.
If a candidate doesn't pass on the first attempt, Maryland requires a 30-day wait before the first retest request, and 60 days for any subsequent retest requests. That waiting period makes first-attempt preparation especially valuable - retesting isn't instant, and each delay pushes back when you can start operating under a Master license.
The Six Exam Domains
The MD-MHVACR exam is built around six content domains that reflect the real, hands-on scope of Master-level HVACR work in Maryland. Understanding how these domains are weighted and what each one actually tests is essential - a full breakdown lives at MD-MHVACR Exam Domains 2026: Complete Guide to All 6 Content Areas, but here's the core structure:
Domain 1: Electrical Knowledge, Motors, and Controls
Covers wiring principles, motor types, control circuits, and diagnostic logic that a Master contractor must understand to troubleshoot system electrical faults.
- Motor starting and control components
- Control circuit troubleshooting logic
Domain 2: Piping
Focuses on piping practices used across refrigerant, gas, and water lines in HVACR installations, including sizing and installation standards.
- Piping materials and joining methods
- Sizing considerations tied to system design
Domain 3: Refrigeration and Air Conditioning
This is the largest domain on the exam, reflecting how central refrigeration and cooling system knowledge is to Master-level HVACR practice in Maryland.
- Refrigeration cycle fundamentals
- Air conditioning system components and diagnostics
Domain 4: Heating Systems
Covers combustion, heating equipment types, and heating system installation and service knowledge.
- Heating equipment types and controls
- Combustion and venting principles
Domain 5: Air Distribution Systems
Tests knowledge of ductwork design, airflow, and distribution system performance - closely tied to referencing tools like the ACCA Ductulator.
- Duct sizing and layout principles
- Airflow measurement and balancing concepts
Domain 6: Safety
Covers jobsite and system safety practices relevant to Master contractors, including standards referenced in OSHA regulations.
- General safety compliance concepts
- Hazard recognition on HVACR jobsites
Because Refrigeration and Air Conditioning is the largest domain, it deserves a disproportionate share of your study time relative to the other five. Candidates who treat all six domains equally often find themselves under-prepared for the sheer volume of refrigeration and AC content on test day.
Approved References for an Open-Book Exam
One of the most distinctive features of the MD-MHVACR exam is that it's open-book - but only with a specific, approved set of references. Candidates may bring:
- The 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
- An ACCA Ductulator
These references may be permanently tabbed, highlighted, and underlined ahead of time, which means preparation isn't just about memorizing content - it's about organizing your physical references so you can flip to the right page under time pressure. However, references may not contain handwritten notes or loose papers, and study guides are explicitly prohibited from the testing room.
Key Takeaway
Spend part of your prep time physically tabbing your approved references by domain topic. On a 4-hour, 100-question exam, the seconds you save flipping directly to a tabbed section add up fast.
After You Pass: License and Insurance
Passing the exam is a milestone, not the finish line. Once you pass, you'll move toward obtaining the actual Master HVACR Contractor license, which currently carries a $94.50 license fee. For a full accounting of every cost involved - exam fee, license fee, and related expenses - see MD-MHVACR Certification Cost 2026: Complete Pricing Breakdown.
Master Contractors who are subject to Maryland's insurance requirement must maintain:
- $300,000 in general-liability insurance
- $100,000 in property-damage insurance
These coverage minimums are part of what makes the Master license meaningful to employers and clients - it signals that the license holder has met not just a knowledge bar, but also financial accountability standards set by the state.
Reciprocity With Other States
Maryland maintains HVACR licensing reciprocity with Delaware and Virginia. For contractors who work across state lines in the Mid-Atlantic region, this reciprocity can simplify the path to holding recognized credentials in neighboring jurisdictions without starting the licensing process completely from scratch. If you're weighing whether pursuing the Maryland Master license makes sense given your regional work plans, Is the MD-MHVACR Certification Worth It? Complete ROI Analysis 2026 walks through the practical tradeoffs.
Preparing for the Exam
Because the MD-MHVACR is open-book but tightly timed, effective preparation blends two things: genuine command of HVACR fundamentals, and fluency navigating your approved references under pressure. A reasonable way to structure your final weeks is to dedicate more time to Refrigeration and Air Conditioning early, since it's the largest domain, then work through Electrical, Piping, Heating, Air Distribution, and Safety in the following weeks, leaving your last stretch for timed practice questions.
Refrigeration and Air Conditioning
- Review refrigeration cycle and AC diagnostics using Modern Refrigeration and Air Conditioning
- Tab relevant sections for quick open-book reference
Electrical, Piping, and Heating
- Work through motor and control circuit scenarios
- Review piping standards and heating equipment fundamentals
Air Distribution and Safety
- Practice duct sizing with the ACCA Ductulator
- Review OSHA 29 CFR Part 1926 safety provisions
Timed Practice
- Run full-length, 100-question timed practice sessions
- Refine reference navigation speed across all six domains
For a structured, exam-specific walkthrough of this entire process, see MD-MHVACR Study Guide 2026: How to Pass on Your First Attempt. If you want a fast-reference companion for last-minute review, MD-MHVACR Cheat Sheet 2026: One-Page Review of Must-Know Facts condenses the must-know facts into one page. And when you're ready to test your readiness under realistic conditions, practice tests on the main site can help you simulate the pacing of a 100-question, 4-hour exam before test day.
It's also worth understanding how test-takers generally perform, which you can explore in MD-MHVACR Pass Rate 2026: What the Data Shows, and what the credential does for your career prospects afterward in MD-MHVACR Salary Guide 2026: Complete Earnings Analysis. Employers hiring for lead technician, project supervisor, and independent contractor roles across Maryland's HVACR sector often list Master licensure as a requirement or strong preference, which is reflected in listings you'll find through MD-MHVACR Jobs.
| Exam Detail | Specification |
|---|---|
| Administering Body | Maryland Board of Heating, Ventilation, Air Conditioning and Refrigeration Contractors (via PSI) |
| Format | Computer-delivered, open-book, multiple-choice |
| Questions | 100 |
| Time Limit | 4 hours |
| Passing Score | 70% |
| Exam Fee | $150 |
| Retest Wait (1st attempt) | 30 days |
| Retest Wait (subsequent) | 60 days |
| Master License Fee | $94.50 |
Frequently Asked Questions
It refers to the Maryland Master HVACR Contractor License Exam, administered by the Maryland Board of Heating, Ventilation, Air Conditioning and Refrigeration Contractors through PSI. For more on the terminology itself, see What Does MD-MHVACR Stand For? and What Does MD-MHVACR Mean?
Yes, but only specific approved references are allowed, including the International Mechanical Code, Modern Refrigeration and Air Conditioning, Manual J, OSHA 29 CFR Part 1926, and an ACCA Ductulator. Study guides and handwritten notes are not permitted.
The exam has 100 multiple-choice questions with a 4-hour time limit, and you need a 70% score to pass.
You must wait 30 days before requesting your first retest. If you fail again, subsequent retest requests require a 60-day wait.
Yes. You need at least three years as a licensed Journeyman, Limited Contractor, Master Restricted Contractor, or HVACR instructor, work under a licensed Master Contractor, and documentation of at least 1,875 HVACR service hours in the preceding year. See MD-MHVACR Requirements 2026: Eligibility, Prerequisites & How to Qualify for full details.