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100+ Free RSES CM Practice Questions

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2026 Statistics

Key Facts: RSES CM Exam

150

Exam Questions

RSES

70%

Passing Score

RSES

18

Knowledge Categories

RSES

~$25

Member Exam Fee

RSES

100

Practice Questions

OpenExamPrep

Foundational

Core HVACR Credential

RSES

The RSES Certificate Member (CM) exam is the foundational HVACR credential awarded by the Refrigeration Service Engineers Society (RSES). It is a 150-question multiple-choice test covering 18 categories of knowledge needed to install and service refrigeration and air conditioning equipment, and a score of 70% or higher is required to pass. Candidates must be RSES members, and the exam is proctored through RSES chapters or approved test sites, with members typically paying about a $25 exam fee. Content spans the refrigeration cycle and components, electrical fundamentals and motors, heating and combustion, air conditioning and psychrometrics, controls, refrigerants and EPA Section 608, and tools, troubleshooting, and system service. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample RSES CM Practice Questions

Try these sample questions to test your RSES CM exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In the basic vapor-compression refrigeration cycle, which component is responsible for absorbing heat from the conditioned space?
A.Condenser
B.Evaporator
C.Compressor
D.Metering device
Explanation: The evaporator is the heat-absorbing component. Low-pressure liquid refrigerant boils inside the evaporator coil, absorbing latent heat from the air or product being cooled, which is the useful refrigeration effect.
2What is the primary function of the compressor in a refrigeration system?
A.To condense the refrigerant vapor into liquid
B.To raise the pressure of the refrigerant vapor and circulate it
C.To meter liquid refrigerant into the evaporator
D.To remove moisture from the refrigerant
Explanation: The compressor is the heart of the system. It draws in low-pressure vapor from the evaporator, raises it to a high pressure and temperature, and pumps it to the condenser, creating the pressure difference that drives refrigerant flow.
3Superheat is defined as the difference between the:
A.Condensing temperature and the outdoor ambient temperature
B.Actual vapor temperature and the saturation temperature at that pressure
C.Liquid temperature and the saturation temperature at the high side
D.Suction pressure and the discharge pressure
Explanation: Superheat is the number of degrees a vapor's temperature is above its saturation (boiling) temperature for the measured pressure. It is measured at the evaporator outlet or suction line by comparing the actual line temperature to the saturated temperature from a P-T chart.
4A technician measures a suction line temperature of 50 F at a saturation temperature of 40 F. What is the superheat?
A.90 F
B.10 F
C.40 F
D.0 F
Explanation: Superheat equals the actual vapor temperature minus the saturation temperature: 50 F minus 40 F = 10 F. A superheat of about 8 to 12 F at the evaporator outlet is typical for many comfort-cooling systems.
5Subcooling is best described as liquid refrigerant that is:
A.Above its saturation temperature for the measured pressure
B.Below its saturation temperature for the measured pressure
C.At exactly its saturation temperature
D.In the process of vaporizing
Explanation: Subcooling is the number of degrees the liquid refrigerant has been cooled below its saturation (condensing) temperature. It is measured at the liquid line and confirms the refrigerant leaving the condenser is fully liquid, typically 10 to 15 F of subcooling on a TXV system.
6Which metering device maintains a constant superheat at the evaporator outlet by modulating refrigerant flow in response to load?
A.Fixed orifice (piston)
B.Capillary tube
C.Thermostatic expansion valve (TXV)
D.Hand expansion valve
Explanation: A thermostatic expansion valve (TXV) uses a remote sensing bulb on the suction line to sense superheat and modulates flow to hold a near-constant superheat across varying loads, improving efficiency and protecting the compressor from flooding.
7In a TXV, the three forces acting on the diaphragm are bulb pressure, evaporator (spring-adjusted) pressure, and:
A.Condenser pressure
B.Spring pressure
C.Atmospheric pressure
D.Discharge pressure
Explanation: A TXV balances three forces: bulb pressure (opening force) versus evaporator pressure plus spring pressure (closing forces). The superheat spring sets the operating superheat, and the bulb senses suction line temperature to modulate the valve.
8What is the purpose of a filter-drier installed in the liquid line of a refrigeration system?
A.To increase refrigerant flow rate
B.To remove moisture and filter contaminants from the refrigerant
C.To meter refrigerant into the evaporator
D.To store excess refrigerant
Explanation: A filter-drier contains a desiccant (such as molecular sieve and activated alumina) and a filtering medium to remove moisture, acids, and particulate contaminants. Moisture must be removed to prevent acid formation, ice at the metering device, and copper plating.
9Bubbles seen in a liquid-line sight glass during steady operation most commonly indicate:
A.The system is overcharged
B.The system is low on refrigerant or has a liquid-line restriction
C.The compressor is short-cycling
D.Excessive subcooling
Explanation: A flashing or bubbling sight glass means the liquid leaving the condenser is not fully subcooled, typically because the charge is low or a restriction (such as a plugged drier) is causing a pressure drop that flashes the liquid to vapor.
10The accumulator in a refrigeration system is installed in the suction line primarily to:
A.Store liquid refrigerant and prevent it from slugging the compressor
B.Increase the system's subcooling
C.Filter the discharge gas
D.Meter refrigerant to the evaporator
Explanation: A suction-line accumulator traps liquid refrigerant returning from the evaporator and meters it back as vapor (often with oil through a small bleed hole), protecting the compressor from liquid slugging that can break valves and bearings.

About the RSES CM Exam

The RSES Certificate Member (CM) exam is the core HVACR knowledge credential of the Refrigeration Service Engineers Society. It is a 150-question multiple-choice exam spanning 18 categories of refrigeration and air conditioning fundamentals, and requires a score of 70% or higher to pass.

Assessment

150 multiple-choice questions covering 18 categories of HVACR fundamentals, 70% required to pass; this practice bank is 100 selected-response items

Time Limit

Proctored; time varies by RSES chapter/test site

Passing Score

70%

Exam Fee

~$25 for RSES members; non-member and chapter pricing varies (Refrigeration Service Engineers Society (RSES))

RSES CM Exam Content Outline

22%

Refrigeration Cycle & Components

Vapor-compression cycle, compressors, condensers, evaporators, metering devices, receivers/accumulators, superheat, subcooling, and latent/sensible heat

16%

Electrical Fundamentals & Motors

Ohm's/Watt's law, series/parallel circuits, single- and three-phase power, PSC/ECM motors, hermetic terminals, capacitors, contactors, and relays

12%

Heating Systems & Combustion

Gas/oil/electric heat, combustion and CO safety, thermocouples and flame rectification, heat exchangers, manifold pressure, and sequence of operation

14%

Air Conditioning & Psychrometrics

Psychrometric chart, dry/wet-bulb, relative humidity, dew point, sensible/latent cooling, airflow, static pressure, temperature split, and SEER2

10%

Controls

Ladder diagrams, NO/NC contacts, low/high-pressure controls, thermostat terminals, defrost and anti-short-cycle timers, reversing valves, and DDC

14%

Refrigerants, EPA Section 608 & Safety

Section 608 certification and venting rules, R-22/R-410A/R-32/R-454B, zeotropic blends, recovery and cylinder safety, the AIM Act, and ASHRAE 34

12%

Tools, Troubleshooting & System Service

Evacuation and micron gauges, manifold gauges, ammeters/multimeters, leak detection, superheat/subcooling charging, lockout/tagout, and diagnosis

How to Pass the RSES CM Exam

What You Need to Know

  • Passing score: 70%
  • Assessment: 150 multiple-choice questions covering 18 categories of HVACR fundamentals, 70% required to pass; this practice bank is 100 selected-response items
  • Time limit: Proctored; time varies by RSES chapter/test site
  • Exam fee: ~$25 for RSES members; non-member and chapter pricing varies

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

RSES CM Study Tips from Top Performers

1Weight your study toward the refrigeration cycle, electrical/motors, and controls, which together make up a large share of the 18 CM categories
2Memorize core values: 1 ton = 12,000 Btu/hr, 144 Btu/lb latent heat of fusion, ~400 CFM per ton, and 24V control voltage
3Practice superheat and subcooling calculations and know which charging method (superheat for fixed-orifice, subcooling for TXV) applies
4Know EPA Section 608 cold: the venting prohibition, certification Types I/II/III, the 80% recovery-cylinder limit, and recovery requirements
5Be fluent with thermostat terminals (R, Y, W, G, C, O/B) and reading ladder/wiring diagrams for sequence of operation
6Complete all 100 practice questions and review every miss with the AI tutor before sitting the exam

Frequently Asked Questions

How many questions are on the RSES CM exam and what score do I need?

The RSES Certificate Member (CM) exam has 150 multiple-choice questions covering 18 categories of HVACR fundamentals, and you need a score of 70% or higher to pass. That means answering at least 105 of the 150 questions correctly.

What does the RSES CM exam cover?

It covers the refrigeration cycle and components, electrical fundamentals and motors, heating and combustion, air conditioning and psychrometrics, controls, refrigerants and EPA Section 608, and tools, troubleshooting, and system service across 18 RSES knowledge categories.

Who is eligible to take the RSES CM exam?

The CM exam is open to RSES members. There is no formal degree requirement, but candidates are expected to have a working knowledge of refrigeration and air conditioning fundamentals from training or field experience.

How much does the RSES CM exam cost?

RSES members typically pay about a $25 exam fee for the CM examination. Pricing for non-members and specific chapter or test-site arrangements may vary, so confirm with RSES or your local chapter.

How is the RSES CM exam administered?

The CM exam is a proctored multiple-choice test offered through RSES chapters and approved test sites. RSES also provides Technical Institute and CM preparation materials to help candidates study the 18 categories.

Is this free RSES CM practice as good as paid prep?

Our 100 practice questions cover the same HVACR content domains as the CM exam, with a teaching explanation for every answer plus free daily AI tutor interactions. All content is free forever and updated for 2026.