- The Air Conditioning - Service specialty exam has 100 questions, separate from the 50-question Core exam.
- You must pass both exams within two years of your first passing examination.
- Content is organized into four domains: Installation, Service, System Components, and Applied Knowledge.
- MACCA's in-person testing rules allow a nonprogrammable calculator; remote proctoring through providers like HVACRedu follows different rules.
What This Cheat Sheet Covers
This is a condensed, one-page-style review for candidates preparing for the NATE-AC-SERVICE credential - the Air Conditioning - Service specialty administered by North American Technician Excellence, Inc. (NATE). It is built specifically around the traditional Air Conditioning - Service track, not the Air Conditioning Installation specialty and not the CHP-5 pathway. If you're still mapping out your full preparation timeline rather than doing a final review, the NATE-AC-SERVICE Study Guide 2026 walks through a complete first-attempt strategy in more depth.
Use this page the way you'd use a pilot's pre-flight checklist: not as your primary study material, but as the last thing you scan before test day to confirm the mechanics, the domain structure, and the high-value technical topics are all fresh in your mind.
The Two-Exam Structure You Must Pass
Certification is not a single test. It requires two separate examinations:
- The specialty exam - 100 questions covering Air Conditioning - Service content.
- The Core exam - 50 questions, kept in a separate bank from the specialty content.
Both must be completed within two years of your first passing examination. That means if you pass the specialty exam first, your clock starts running immediately, and you need to schedule the Core exam (or vice versa) well inside that two-year window. Treat the "Exam" line item you see on testing schedules as the specialty exam alone - it does not represent a combined Core-and-specialty sitting, so don't assume one registration covers both.
Key Takeaway
Never let the two-year clock become an afterthought. Schedule your second exam the same week you pass your first one, even if the test date itself is months out.
For a deeper breakdown of how the passing threshold is calculated for each exam, see the NATE-AC-SERVICE Passing Score 2026 guide, and for a realistic assessment of how challenging candidates find each portion, check How Hard Is the NATE-AC-SERVICE Exam?
The Four Domains at a Glance
The specialty exam's 100 questions are organized around four content domains. Knowing what each domain actually tests - not just its name - is what separates a quick cheat sheet from a useless one.
Domain 1: Installation
Even though this is the Service specialty, installation-adjacent knowledge still appears because service technicians must evaluate whether a system was set up correctly before diagnosing a complaint.
- Verifying proper equipment sizing and placement as a precondition for service work
- Recognizing installation errors that mimic service failures
- Confirming airflow and duct configuration match design intent
Domain 2: Service
This is the heart of the exam. Expect scenario-based questions built around real service calls.
- Charging methods and confirming correct refrigerant charge
- Superheat and subcooling calculations and interpretation
- Leak testing procedures and evacuation practices
- Symptom-based diagnosis: matching complaints to root causes
Domain 3: System Components
This domain checks whether you understand what each part of the refrigerant circuit and electrical system actually does, not just how to name it.
- Refrigerant circuit components and their function under normal vs. faulty operation
- Electrical controls, safety devices, and how they interact with the mechanical system
- Component-level failure signatures
Domain 4: Applied Knowledge
Applied Knowledge blends the other three domains into original, scenario-driven questions rather than isolated fact recall.
- Multi-symptom troubleshooting scenarios
- Airflow problems that present as electrical or refrigerant issues
- Judgment calls where more than one answer looks partially correct
For a full breakdown of how these domains interrelate and how test writers tend to phrase questions in each, the NATE-AC-SERVICE Exam Domains 2026 Complete Guide is the companion resource to this cheat sheet.
Core Technical Topics You'll Be Tested On
Across all four domains, certain technical themes recur constantly. If you only have time to drill a short list before test day, this is that list:
- Refrigerant circuits - pressure-temperature relationships, state changes, and circuit troubleshooting logic
- Superheat and subcooling - how to calculate each, what a reading outside normal range implies, and which charging method depends on which measurement
- Charging methods - weight charging, superheat method, subcooling method, and when each is appropriate
- Airflow - static pressure, CFM expectations, and how restricted or excessive airflow masquerades as a refrigerant problem
- Electrical controls - contactors, relays, capacitors, safety switches, and sequence-of-operation logic
- Leak testing - method selection and interpreting results correctly
- Evacuation - target vacuum levels, triple-evacuation logic, and why moisture removal matters for long-term system health
- Symptom-based diagnosis - working backward from a customer complaint to a specific, testable hypothesis
Registration, Calculators, and Testing Formats
Registration for the NATE-AC-SERVICE specialty exam runs through a NATE testing organization rather than through NATE directly. Two mechanics worth locking in before test day:
- In-person testing: Organizations such as MACCA publish their own instructions for in-person sessions, including permission to bring a nonprogrammable calculator. Confirm the specific rules for your test site rather than assuming a blanket policy applies everywhere.
- Remote/online proctored testing: NATE training provider HVACRedu describes live online proctored testing as an alternative format. Remote-session instructions are not the same as in-person instructions - don't mix the two up when you're prepping your testing-day logistics.
For item-level mapping of exactly which knowledge points fall under which domain, the official reference is the Air Conditioning - Service Knowledge Areas of Technician Expertise (KATE) document. If you want a plain-language walkthrough of registration steps and fee mechanics rather than the raw source document, see NATE-AC-SERVICE Certification Cost 2026: Complete Pricing Breakdown and NATE-AC-SERVICE Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
| Attribute | Specialty Exam (AC - Service) | Core Exam |
|---|---|---|
| Question count | 100 questions | 50 questions |
| Content focus | Installation, Service, System Components, Applied Knowledge for AC service | General HVAC/R foundational knowledge, separate item bank |
| Completion window | Must be completed within two years of first passing exam | Must be completed within two years of first passing exam |
| Registration path | Through a NATE testing organization | Through a NATE testing organization |
Renewal: Keeping Your Certification Active
Passing both exams isn't the end of the process - it's the start of a renewal cycle. NATE-AC-SERVICE certification is maintained through a continuing-education renewal route: 16 relevant continuing-education hours completed within a two-year cycle. Track your CE hours the same way you'd track any recurring license requirement - don't wait until the final months of the cycle to start collecting credit.
If you're weighing whether the ongoing renewal commitment is worth the career payoff, Is the NATE-AC-SERVICE Certification Worth It? Complete ROI Analysis 2026 covers that tradeoff directly, and NATE-AC-SERVICE Jobs looks at where employers specifically ask for this credential on job postings.
A One-Week Domain-by-Domain Review Plan
Generic study techniques - spaced repetition, timed drills, flashcards - only help if they're pointed at the right domain at the right time. Here's a compressed final-week plan built around the four domains above rather than a generic template:
Service Domain Deep Review
- Redo superheat/subcooling calculations until they're automatic
- Rehearse all three charging methods and when each applies
- Drill leak testing and evacuation procedures
System Components Refresh
- Walk through refrigerant circuit components function-by-function
- Review electrical control sequences and common failure points
Installation-Adjacent Concepts
- Review sizing, placement, and duct/airflow design basics as they relate to service diagnosis
Applied Knowledge Scenarios
- Practice full symptom-based diagnosis scenarios that blend multiple domains
- Time yourself on scenario questions to build pacing confidence
Logistics and Light Review
- Confirm your testing format (in-person vs. remote) and what's allowed, including calculator rules
- Light review only - no new material
For a more thorough version of this plan spread across several weeks rather than a final cram week, revisit the NATE-AC-SERVICE Study Guide 2026. And when you're ready to test your recall under exam-like conditions, running timed scenario questions on our practice test platform is one of the fastest ways to find weak spots before the real exam does.
Frequently Asked Questions
No. This cheat sheet covers the Air Conditioning - Service specialty specifically, which is distinct from the Air Conditioning Installation specialty and from the CHP-5 pathway. Each has its own content focus, even though some underlying HVAC knowledge overlaps.
No. They are separate examinations, and the "Exam" designation typically refers to the specialty exam alone. You do need to complete both within two years of your first passing exam, but they can be scheduled separately.
In-person testing instructions from organizations like MACCA permit a nonprogrammable calculator. Remote or online proctored testing sessions, such as those described by HVACRedu, may have different rules, so confirm the specific instructions for your chosen testing format in advance.
Renewal is handled through continuing education: 16 relevant continuing-education hours completed within a two-year cycle. Start logging qualifying CE hours early in the cycle rather than scrambling near the deadline.
The Air Conditioning - Service Knowledge Areas of Technician Expertise (KATE) document is the official item-level mapping source. For a more digestible breakdown organized by domain, see the NATE-AC-SERVICE Exam Domains 2026 Complete Guide, and for background on what the credential is and who it's for, start with What Is NATE-AC-SERVICE?