4.10 - Practice Questions

Module: Refrigeration Cycle Components Gauges and Pressure-Temperature Relationships
Covers: Sections 4.1–4.9
Question type: Original EPA 608-style multiple-choice practice
Technical verification basis: Module 4 content reviewed through August 9, 2026
Answers: See 4.11 - Answers and Explanations.md

Instructions

• Select the single best answer for each question.
• Complete the entire set without notes or external references when using it as a cumulative assessment.
• Record a confidence code for every answer:
  • C3 — certain and can explain the reason.
  • C2 — probably correct but not fully certain.
  • C1 — guessed between two or more choices.
  • C0 — no reliable basis for the answer.
• Enter every incorrect, C1, and C0 response in the project error log.
• Review the detailed explanations only after completing all questions.
• A correct guess is not considered mastered.
• Pay close attention to refrigerant state, flow direction, pressure side, pressure reference, bubble/dew selection, and the order of subtraction in superheat and subcooling calculations.
• These are original project questions. They are not actual EPA examination questions and are not represented as questions from any certifying provider.

Practice Record

• Date:
• Time started:
• Time completed:
• Testing condition: Closed-book
• Question set: Module 4 Practice Set
• Correct answers: ___ / 35
• Low-confidence answers (C0–C1):
• Topics requiring review:
• Open critical technical errors after review:

This 35-question module set is a cumulative learning assessment. The project’s separate Confirmed Ready standard of 22–25 correct out of 25 on two independent closed-book attempts applies to the project’s 25-question section-readiness assessments.

Coverage

Question 1

Which sequence correctly follows refrigerant flow through the four major components of a basic vapor-compression refrigeration cycle?

A. Compressor → Evaporator → Metering Device → Condenser → Compressor

B. Compressor → Condenser → Metering Device → Evaporator → Compressor

C. Condenser → Compressor → Evaporator → Metering Device → Condenser

D. Metering Device → Compressor → Condenser → Evaporator → Metering Device

Question 2

Which component receives mechanical or electrical work input and raises the refrigerant pressure?

A. Evaporator

B. Condenser

C. Compressor

D. Metering device

Question 3

Which component primarily absorbs heat from the cooled space or load?

A. Evaporator

B. Compressor

C. Condenser

D. Receiver

Question 4

Which component creates the major pressure drop from the high-pressure side to the low-pressure side?

A. Compressor

B. Condenser

C. Accumulator

D. Metering device

Question 5

In the simplified cycle model, what is the refrigerant condition immediately after leaving the compressor?

A. Low-pressure liquid

B. High-pressure high-temperature vapor

C. Low-pressure liquid-vapor mixture

D. High-pressure subcooled liquid

Question 6

What is the simplified refrigerant condition immediately after the metering device?

A. High-pressure vapor

B. High-pressure liquid

C. Low-pressure liquid-vapor mixture

D. Low-pressure superheated vapor only

Question 7

Which refrigerant line normally carries high-pressure vapor from the compressor to the condenser?

A. Discharge line

B. Liquid line

C. Suction line

D. Equalizer line

Question 8

Which line normally carries high-pressure liquid from the condenser toward the metering device?

A. Suction line

B. Liquid line

C. Discharge line

D. Evaporator return line

Question 9

Which line normally carries low-pressure vapor from the evaporator toward the compressor?

A. Discharge line

B. Liquid line

C. Receiver line

D. Suction line

Question 10

Where is a receiver normally located in the refrigerant circuit?

A. Between the evaporator and compressor on the suction side

B. Between the compressor and condenser in the discharge line

C. After the condenser and before the metering device on the high-pressure liquid side

D. Immediately after the metering device on the low-pressure side

Question 11

What is the primary purpose of a suction accumulator?

A. To store high-pressure liquid before the metering device

B. To separate excess liquid from suction vapor and help protect the compressor

C. To remove noncondensable gases from the condenser

D. To create the main system pressure drop

Question 12

What is the primary function of a refrigerant filter-drier?

A. To remove moisture and particles from the refrigerant circuit

B. To remove all air and nitrogen from the system

C. To measure liquid-line pressure

D. To store liquid refrigerant during normal operation

Question 13

A technician observes bubbles in a liquid-line sight glass. Which conclusion is most appropriate?

A. The system is definitely undercharged.

B. The compressor is definitely damaged.

C. The filter-drier has definitely failed.

D. The observation must be interpreted with other system information and does not by itself prove undercharge.

Question 14

What is the primary function of the compound gauge on a traditional manifold gauge set?

A. It measures only high-side discharge pressure.

B. It measures low-side positive pressure and provides a rough vacuum indication.

C. It measures deep vacuum accurately in microns.

D. It controls refrigerant flow through the center hose.

Question 15

Which gauge is normally connected to the system high-pressure access point?

A. Micron gauge only

B. Compound gauge

C. High-pressure gauge

D. Vacuum gauge only

Question 16

On a traditional manifold gauge set, which hose or port is normally used to connect a refrigerant source, recovery machine, or vacuum pump?

A. Center service hose

B. High-side red hose

C. Low-side blue hose

D. Gauge-face vent

Question 17

Where should the red high-side hose normally be connected when both sides of the system are being monitored?

A. Refrigerant supply cylinder

B. Vacuum pump inlet

C. Recovery-cylinder vapor port

D. System high-pressure access point

Question 18

On a traditional two-valve manifold, both manifold valves are closed while the low- and high-side hoses remain connected to the system. Which statement is correct?

A. Neither gauge can indicate system pressure.

B. The gauges can still indicate their respective system pressures while the valves block flow through the manifold toward the center port.

C. The center hose automatically becomes connected to both system sides.

D. Closing the valves converts both gauges into micron gauges.

Question 19

Assuming standard sea-level atmospheric pressure, approximately what absolute pressure corresponds to 0 psig?

A. 0 psia

B. 1 psia

C. 14.7 psia

D. 29.92 psia

Question 20

What is the reference point for absolute pressure?

A. Perfect vacuum

B. Local atmospheric pressure

C. Saturation pressure of water

D. The low-side gauge zero

Question 21

How many microns are equal to 1 mm Hg absolute?

A. 25.4 microns

B. 100 microns

C. 760 microns

D. 1,000 microns

Question 22

Which statement correctly describes a micron reading during evacuation?

A. A larger micron value always means a deeper vacuum.

B. A smaller micron value means a lower absolute pressure and therefore a deeper vacuum.

C. Microns are gauge pressure measured above atmospheric pressure.

D. A micron reading cannot be used during evacuation.

Question 23

Which instrument is most appropriate for verifying a deep evacuation?

A. High-pressure gauge

B. Standard compound gauge alone

C. Micron gauge

D. Liquid-line sight glass

Question 24

What two properties are directly related by a refrigerant pressure-temperature chart at saturation?

A. Saturation pressure and saturation temperature

B. Compressor amperage and refrigerant mass

C. Airflow and line temperature

D. Oil viscosity and receiver volume

Reference Data for Questions 25–26

Use the following R-134a saturation data:

Question 25

A technician measures a stabilized R-134a saturation pressure of 35.0 psig. Using the supplied P-T data, what is the corresponding saturation temperature?

A. 25°F

B. 40°F

C. 45.4°F

D. 50°F

Question 26

A technician measures an R-134a saturation pressure of 45.4 psig. Using the supplied P-T data, what is the corresponding saturation temperature?

A. 22.1°F

B. 35°F

C. 45.4°F

D. 50°F

Question 27

A cylinder containing a known refrigerant has both liquid and vapor present and has been allowed to stabilize. Its measured pressure is substantially higher than the expected saturation pressure at the measured temperature. What is the best interpretation?

A. Investigate possible causes such as noncondensables, wrong or mixed refrigerant, or measurement error.

B. The pressure difference proves the cylinder is overfilled.

C. The refrigerant is definitely pure.

D. The cylinder must contain only liquid refrigerant.

Question 28

For a zeotropic refrigerant blend, which saturation reference is normally used when evaluating vapor superheat?

A. Bubble point

B. Critical point

C. Dew point

D. Triple point

Question 29

For a zeotropic refrigerant blend, which saturation reference is normally used when evaluating liquid subcooling?

A. Dew point

B. Bubble point

C. Critical point

D. Average of bubble and dew in every case

Question 30

Which expression correctly calculates superheat?

A. Vapor saturation temperature − actual vapor temperature

B. Actual liquid temperature − liquid saturation temperature

C. Liquid saturation temperature − actual liquid temperature

D. Actual vapor temperature − vapor saturation temperature

Question 31

At the measured suction pressure, the P-T reference gives a vapor saturation temperature of 42°F. The actual vapor-line temperature is 56°F. What is the superheat?

A. 14°F

B. 42°F

C. 56°F

D. 98°F

Question 32

Which expression correctly calculates subcooling?

A. Actual vapor temperature − vapor saturation temperature

B. Actual liquid temperature − liquid saturation temperature

C. Liquid saturation temperature − actual liquid temperature

D. Vapor saturation temperature − actual vapor temperature

Question 33

At the measured liquid-side pressure, the P-T reference gives a liquid saturation temperature of 105°F. The actual liquid-line temperature is 94°F. What is the subcooling?

A. 9°F

B. 11°F

C. 94°F

D. 199°F

Question 34

A technician measures higher-than-expected superheat. Which conclusion is most appropriate?

A. The system is definitely overcharged.

B. The compressor is definitely failing.

C. The condenser is definitely flooded with liquid.

D. Several conditions can produce high superheat, so the reading must be interpreted with system design, load, refrigerant flow, and other measurements.

Question 35

Why should the pressure and line-temperature measurements used for a superheat or subcooling calculation represent the same relevant refrigerant condition?

A. Pressure can change through piping and components, which changes the corresponding saturation temperature.

B. Refrigerant pressure has no relationship to saturation temperature.

C. Line temperature is constant throughout the entire refrigeration cycle.

D. Superheat and subcooling depend only on temperature and never on pressure.

Answers and detailed explanations will be provided in 4.11 - Answers and Explanations.md.