308A Red Seal — Refrigeration & AC Mechanic

About the 308A Red Seal Exam — Refrigeration & AC Mechanic

The 308A Refrigeration and Air Conditioning Mechanic Red Seal exam is Canada's national certification for technicians who install, maintain, and service commercial and industrial refrigeration systems, HVAC equipment, and process cooling. Refrigeration mechanics with Red Seal status are in high demand across food processing, cold storage, commercial real estate, and industrial facilities.

The exam consists of 120 multiple-choice questions based on the 2023 Red Seal Occupational Standard (RSOS), requiring a minimum score of 70%. Exam time is 3 hours.

Topic Breakdown (2023 RSOS)

• Refrigeration Theory & Cycle Analysis (~25%) — The foundation of the exam. Vapour-compression cycle (evaporation, compression, condensation, expansion), P-H diagrams (Mollier charts), subcooling and superheat calculations, COP and system efficiency. You must be able to read a P-H diagram and diagnose system performance from it.
• Refrigerants & Environmental Regulations (~20%) — Refrigerant properties (R-404A, R-410A, R-134a, R-744 CO₂, R-290 propane, low-GWP alternatives), HCFC phase-out schedules, Environment and Climate Change Canada (ECCC) regulations, refrigerant recovery and handling (TSSA/CSA B52), and leak detection methods.
• Compressors (~18%) — Reciprocating, scroll, screw, and centrifugal compressor operation, capacity control, valve diagnostics, oil management, and failure analysis. Suction and discharge pressure relationships.
• Electrical Controls & Automation (~17%) — Ladder logic, sequencing controls, solid-state relays, VFDs for compressors and fans, DDC/BAS system integration, pressure and temperature controllers, and safety control circuit testing.
• Condensers, Evaporators & Heat Transfer (~12%) — Air-cooled and water-cooled condensers, cooling tower operation, evaporative condensers, direct-expansion and flooded evaporator circuits, defrost methods (electric, hot gas, off-cycle).
• Piping, System Installation & Safety (~8%) — CSA B52 Mechanical Refrigeration Code, pipe sizing, pressure testing, nitrogen purging, refrigerant charge verification, and machine room requirements.

Exam Strategy for 308A

Master the P-H diagram. Pressure-enthalpy diagrams appear in multiple 308A questions. Practice plotting a complete cycle, identifying subcooling and superheat zones, and diagnosing abnormal conditions (high discharge temp, liquid slugging, flash gas in the liquid line).

Know the current refrigerants. Questions on low-GWP refrigerants (R-32, R-454B, R-744) have increased with each RSOS revision. Understand their flammability classification (A2L), pressure behaviour, and oil compatibility.

Electrical controls are heavily tested. The 308A has increased its electrical/controls weighting significantly. Expect ladder logic diagrams, VFD parameter questions, and DDC setpoint questions.

How to Use This Practice Tool

This tool includes 115 questions covering all 308A topic blocks with full answer explanations. Filter by topic to drill refrigeration cycle calculations and refrigerant properties — the two areas where most candidates lose marks. Use Mock Exam Mode to practice under timed conditions.

Related reading: How to Pass the 308A Red Seal Exam | 308A Salary Guide | 308A Career Guide