HVACR 2025/2026 Study Guide: Core Principles & Safety
1. What is the primary purpose of the HVACR system?
ANSWER ✓ To control the environment within a conditioned space by managing
temperature, humidity, air quality, and air circulation (for refrigeration, specifically to
preserve food and other perishables).
2. What does the acronym HVACR stand for?
ANSWER ✓ Heating, Ventilation, Air Conditioning, and Refrigeration.
3. What are the four main processes of the refrigeration cycle?
ANSWER ✓ Compression, Condensation, Expansion, and Evaporation.
4. Why is safety the most critical aspect of HVACR work?
ANSWER ✓ Technicians work with high voltages, pressurized systems, heavy equipment,
and potentially hazardous refrigerants. A safety-first mindset prevents serious injury,
fatalities, and property damage.
5. What personal protective equipment (PPE) is essential for basic HVACR tasks?
ANSWER ✓ Safety glasses, cut-resistant gloves, sturdy work boots, and appropriate
clothing. Specific tasks may require respirators, hearing protection, or arc-flash gear.
6. What is the primary hazard associated with refrigerants?
ANSWER ✓ Asphyxiation in confined spaces due to displacement of oxygen, and
frostbite from contact with liquid refrigerant during a rapid pressure release.
7. What does the GHS pictogram for compressed gases indicate?
ANSWER ✓ It indicates the contents of the cylinder are under high pressure and can
rupture explosively if mishandled or exposed to heat.
8. Why must oxygen never be used to pressurize a system for leak checking?
ANSWER ✓ Oxygen under pressure can cause oils and other materials to explode
violently.
9. What is the purpose of a Material Safety Data Sheet (MSDS/SDS)?
ANSWER ✓ To provide detailed information on the properties, hazards, safe handling,
and emergency procedures for a specific chemical substance, such as refrigerant or
cleaning agents.
, 10. What is the first step before servicing any electrical component?
ANSWER ✓ To disconnect and lock out/tag out (LOTO) all power sources to the unit to
prevent accidental energization.
Refrigeration Cycle & Components
11. In the refrigeration cycle, where does heat absorption occur?
ANSWER ✓ In the evaporator.
12. What is the state of the refrigerant as it enters the compressor?
ANSWER ✓ A low-pressure, low-temperature superheated vapor.
13. What is the state of the refrigerant as it leaves the compressor?
ANSWER ✓ A high-pressure, high-temperature superheated vapor.
14. What is the primary function of the metering device?
ANSWER ✓ To create a pressure drop, which lowers the boiling point of the refrigerant,
allowing it to evaporate at a low temperature in the evaporator.
15. What are the two main types of metering devices?
ANSWER ✓ Fixed restriction (e.g., piston/orifice) and variable restriction (e.g.,
Thermostatic Expansion Valve - TXV, or Electronic Expansion Valve - EEV).
16. How does a Thermostatic Expansion Valve (TXV) modulate refrigerant flow?
ANSWER ✓ It uses a sensing bulb filled with a refrigerant charge to monitor the
superheat at the evaporator outlet and adjusts the valve opening to maintain a constant
superheat.
17. What is the function of the condenser?
ANSWER ✓ To reject the heat absorbed from the conditioned space (and heat of
compression) from the refrigerant to the outside air (or water).
18. What is "subcooling"?
ANSWER ✓ The process of cooling liquid refrigerant below its saturation temperature
(condensing temperature) at a given pressure.
19. Where is subcooling measured?
ANSWER ✓ At the bottom of the condenser or the liquid line, after the refrigerant has
fully condensed into a liquid.
1. What is the primary purpose of the HVACR system?
ANSWER ✓ To control the environment within a conditioned space by managing
temperature, humidity, air quality, and air circulation (for refrigeration, specifically to
preserve food and other perishables).
2. What does the acronym HVACR stand for?
ANSWER ✓ Heating, Ventilation, Air Conditioning, and Refrigeration.
3. What are the four main processes of the refrigeration cycle?
ANSWER ✓ Compression, Condensation, Expansion, and Evaporation.
4. Why is safety the most critical aspect of HVACR work?
ANSWER ✓ Technicians work with high voltages, pressurized systems, heavy equipment,
and potentially hazardous refrigerants. A safety-first mindset prevents serious injury,
fatalities, and property damage.
5. What personal protective equipment (PPE) is essential for basic HVACR tasks?
ANSWER ✓ Safety glasses, cut-resistant gloves, sturdy work boots, and appropriate
clothing. Specific tasks may require respirators, hearing protection, or arc-flash gear.
6. What is the primary hazard associated with refrigerants?
ANSWER ✓ Asphyxiation in confined spaces due to displacement of oxygen, and
frostbite from contact with liquid refrigerant during a rapid pressure release.
7. What does the GHS pictogram for compressed gases indicate?
ANSWER ✓ It indicates the contents of the cylinder are under high pressure and can
rupture explosively if mishandled or exposed to heat.
8. Why must oxygen never be used to pressurize a system for leak checking?
ANSWER ✓ Oxygen under pressure can cause oils and other materials to explode
violently.
9. What is the purpose of a Material Safety Data Sheet (MSDS/SDS)?
ANSWER ✓ To provide detailed information on the properties, hazards, safe handling,
and emergency procedures for a specific chemical substance, such as refrigerant or
cleaning agents.
, 10. What is the first step before servicing any electrical component?
ANSWER ✓ To disconnect and lock out/tag out (LOTO) all power sources to the unit to
prevent accidental energization.
Refrigeration Cycle & Components
11. In the refrigeration cycle, where does heat absorption occur?
ANSWER ✓ In the evaporator.
12. What is the state of the refrigerant as it enters the compressor?
ANSWER ✓ A low-pressure, low-temperature superheated vapor.
13. What is the state of the refrigerant as it leaves the compressor?
ANSWER ✓ A high-pressure, high-temperature superheated vapor.
14. What is the primary function of the metering device?
ANSWER ✓ To create a pressure drop, which lowers the boiling point of the refrigerant,
allowing it to evaporate at a low temperature in the evaporator.
15. What are the two main types of metering devices?
ANSWER ✓ Fixed restriction (e.g., piston/orifice) and variable restriction (e.g.,
Thermostatic Expansion Valve - TXV, or Electronic Expansion Valve - EEV).
16. How does a Thermostatic Expansion Valve (TXV) modulate refrigerant flow?
ANSWER ✓ It uses a sensing bulb filled with a refrigerant charge to monitor the
superheat at the evaporator outlet and adjusts the valve opening to maintain a constant
superheat.
17. What is the function of the condenser?
ANSWER ✓ To reject the heat absorbed from the conditioned space (and heat of
compression) from the refrigerant to the outside air (or water).
18. What is "subcooling"?
ANSWER ✓ The process of cooling liquid refrigerant below its saturation temperature
(condensing temperature) at a given pressure.
19. Where is subcooling measured?
ANSWER ✓ At the bottom of the condenser or the liquid line, after the refrigerant has
fully condensed into a liquid.
