100+ Free NVQ L4 Automobile AC Technician Practice Questions

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2026 Statistics

Key Facts: NVQ L4 Automobile AC Technician Exam

60-70%

Pass Rate

TVEC Statistics

50%

Passing Score

Theory minimum

Exam Questions

Theory Paper MCQ

30%

Component Service

Largest exam weight

2 Years

RPL Experience

Alternative route entry

G50S024

TVEC Code

NCS Standard

The NVQ Level 4 Automobile Air Conditioning Technician theory exam tests critical diagnostic and safety skills. Focusing on the G50S024 National Competency Standard, the exam covers key domains from electrical wiring to transport refrigeration. Candidates must demonstrate competence in all modules to secure certification, opening career pathways in specialized automotive repair and fleet services across Sri Lanka.

Sample NVQ L4 Automobile AC Technician Practice Questions

Try these sample questions to test your NVQ L4 Automobile AC Technician exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1During a manifold gauge test on an R-134a system at an 85°F (29°C) ambient temperature, the low-side reads 10 psi and the high-side reads 110 psi. What is the most likely cause?

A.The system is undercharged with refrigerant.

B.The system is overcharged with refrigerant.

C.The condenser fan motor has failed.

D.The compressor reed valves are broken.

Explanation: At 85°F ambient, normal R-134a pressures are typically 30-45 psi on the low-side and 180-220 psi on the high-side. Both pressures being significantly below normal indicates an undercharged system due to a refrigerant leak.

2What physical change occurs to the refrigerant as it passes through the condenser in an automobile air conditioning system?

A.It changes from a high-pressure gas to a high-pressure liquid.

B.It changes from a low-pressure liquid to a low-pressure gas.

C.It changes from a high-pressure liquid to a low-pressure liquid.

D.It changes from a low-pressure gas to a high-pressure gas.

Explanation: The condenser's function is to reject heat from the compressed, hot refrigerant vapor to the outside air. As the refrigerant cools down inside the condenser tubes under high pressure, it condenses from a gas into a liquid.

3A technician notices that an A/C system's low-side pressure is 55 psi and the high-side is 120 psi while the compressor is running. When the engine speed is increased, the pressures barely change. What is the most likely diagnosis?

A.The compressor has failed internally and has low pumping efficiency.

B.The expansion valve is restricted or stuck closed.

C.The system has a severe restriction in the liquid line.

D.The condenser airflow is blocked.

Explanation: When low-side pressure is higher than normal (e.g., 55 psi) and high-side pressure is lower than normal (e.g., 120 psi), the compressor is not building a sufficient pressure differential. This is a classic sign of worn piston rings, damaged scroll seals, or leaking reed valves in the compressor.

4Where should the sensing bulb of a Thermostatic Expansion Valve (TXV) be mounted for proper system operation?

A.On the evaporator outlet pipe, insulated and positioned at the 10 o'clock or 2 o'clock position.

B.On the evaporator inlet pipe, exposed to the ambient airflow.

C.On the compressor discharge line, close to the condenser inlet.

D.Directly inside the receiver-drier container, submerged in liquid refrigerant.

Explanation: The TXV sensing bulb monitors the temperature of the refrigerant vapor leaving the evaporator. It must be mounted on a horizontal section of the evaporator outlet (suction) line, insulated to prevent ambient temperature interference, and positioned at 10 or 2 o'clock to avoid reading oil lying at the bottom of the tube.

5Which A/C system component is designed specifically to prevent liquid refrigerant slugging from entering the compressor suction port in an orifice tube system?

A.The accumulator

B.The receiver-drier

C.The thermostatic expansion valve

D.The liquid line sight glass

Explanation: An accumulator is located on the low-pressure side (evaporator outlet) of an orifice tube system. Its primary role is to catch any unvaporized liquid refrigerant and store it, allowing only vapor to be drawn into the compressor suction port, thus protecting the compressor from liquid slugging.

6A technician connects a manifold gauge set and reads 250 psi on the high-side and 32 psi on the low-side. The ambient temperature is 80°F (27°C). After spraying water on the condenser, the high-side pressure drops to 160 psi. What does this test indicate?

A.The condenser airflow is inadequate or the condenser fan is weak.

B.The system has an excessive amount of compressor oil.

C.The expansion valve is stuck wide open.

D.The compressor clutch is slipping under high load.

Explanation: A high-side pressure of 250 psi at 80°F is excessive. When spraying water on the condenser artificially cools it and rapidly drops the pressure back to normal (160 psi), it proves that the refrigerant is not condensing properly due to insufficient airflow (fan failure, clogged fins, shroud missing) rather than an overcharge.

7What is the function of the desiccant bag found inside a receiver-drier or accumulator?

A.To absorb moisture and prevent acid formation in the A/C system.

B.To filter out large metal particles from a failing compressor.

C.To separate liquid refrigerant from vapor refrigerant.

D.To regulate the pressure drop of the refrigerant.

Explanation: Moisture in an A/C system can react with refrigerant and lubricant to form highly corrosive acids (like hydrochloric acid). The desiccant bag contains silica gel or zeolites that attract and hold moisture, keeping the internal system dry and preventing internal corrosion.

8An A/C system uses a variable displacement compressor. During testing, the low-side pressure stays at 30 psi regardless of engine speed, and vent temperatures are cool. What does this indicate?

A.The system is operating normally.

B.The compressor control valve is stuck in maximum displacement.

C.The expansion valve is restricted.

D.The system is severely undercharged.

Explanation: A variable displacement compressor adjusts its stroke (displacement) to maintain a constant suction pressure (typically 28-32 psi) regardless of engine RPM or heat load. A constant low-side pressure and cool vent temps show the system is modulating properly.

9Frost is forming on the inlet line of the accumulator in an orifice-tube A/C system. What is the most likely cause?

A.Low airflow across the evaporator due to a clogged cabin filter or bad blower.

B.The system is completely overcharged with refrigerant.

C.The orifice tube is completely missing from the line.

D.The compressor clutch is stuck in the engaged position.

Explanation: If airflow across the evaporator is severely restricted (clogged cabin filter, dirty evaporator fins, or failing blower motor), the refrigerant cannot absorb enough heat to boil completely. Liquid refrigerant leaves the evaporator and continues boiling in the suction line and accumulator inlet, causing frost to form.

10Which type of leak detector is recommended for finding very small leaks in an R-1234yf system and is certified to SAE J2913 standards?

A.An electronic corona-discharge leak detector.

B.A heated-diode or infrared electronic leak detector.

C.A propane halide torch leak detector.

D.A soap bubble solution applied to the fittings.

Explanation: R-1234yf is mildly flammable (A2L classification). Heated-diode and infrared electronic leak detectors certified to SAE J2913 are highly sensitive to R-1234yf and do not create sparks, making them the industry standard and safest choice for finding micro-leaks.

About the NVQ L4 Automobile AC Technician Exam

The Sri Lanka NVQ Level 4 Automobile Air Conditioning Technician written exam (G50S024) measures essential knowledge in automotive HVAC systems. This includes servicing, diagnosing, and repairing A/C and heating systems, working with electrical circuits and sensors, executing safe refrigerant recovery and recharging (R134a/R1234yf), maintaining refrigerated truck units (reefers), estimating costs, and adhering to environmental and workplace safety regulations.

Questions

40 scored questions

Time Limit

2 hours

Passing Score

50%

Exam Fee

Rs. 1,500 (Tertiary and Vocational Education Commission (TVEC), Sri Lanka)

NVQ L4 Automobile AC Technician Exam Content Outline

30%

A/C Service & Component Diagnosis

Troubleshooting and repairing compressors, condensers, evaporators, thermostatic expansion valves (TXV), and orifice tubes using pressure gauges.

25%

Electrical Controls, Sensors & Circuits

Testing blower resistors, relays, electromagnetic clutch circuits, thermistors, pressure switches, actuators, and automatic climate control units.

25%

Refrigerant Recovery, Charging & OHS

Safe recovery of R134a and R1234yf, system evacuation and leak testing, lubricant oil management (PAG/POE), and OHS gas handling rules.

10%

Transport Refrigeration

Servicing truck reefers, diesel-standby power configurations, defrost solenoid logic, and insulation integrity.

10%

Customer Interaction & Cost Estimation

Interpreting customer AC issues, drafting repair estimates, computing refrigerant and labor costs.

How to Pass the NVQ L4 Automobile AC Technician Exam

What You Need to Know

Passing score: 50%
Exam length: 40 questions
Time limit: 2 hours
Exam fee: Rs. 1,500

Keys to Passing

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

NVQ L4 Automobile AC Technician Study Tips from Top Performers

1Master the refrigeration cycle, including the state changes of refrigerant between high-pressure gas/liquid and low-pressure gas/liquid.

2Study electrical wiring diagrams, including how relays, thermostats, pressure switches, and blower speed resistors operate.

3Understand manifold gauge readings for diagnosing common faults such as restrictions, compressor failure, or overcharging.

4Learn the recovery and recharging procedures, including vacuum levels, oil balancing, and safety rules for handling pressurized refrigerants.

5Review the specialized components of transport refrigeration units (reefers) on refrigerated trucks, including separate power sources and defrost mechanisms.

6Be prepared for cost calculation and estimation questions related to labor, parts, and refrigerant quantities.

Frequently Asked Questions

What is the Sri Lanka NVQ Level 4 Automobile AC Technician exam pass mark?

The exam requires a 'Competent' rating, which corresponds to achieving 50% or above in the theory written assessment, in addition to passing the practical evaluation.

How do I register for the NVQ Level 4 assessment?

Candidates can register through TVEC-accredited centers, or apply through NAITA or VTA under the RPL (Recognition of Prior Learning) program if they have 2+ years of industry experience.

What topics are covered in the G50S024 curriculum?

The G50S024 standard covers customer interaction and cost estimation, troubleshooting and repairing A/C systems, refrigerant recovery/recycling, transport refrigeration (refrigerated trucks), and occupational safety (OHS).

Is there a practical component to the NVQ Level 4 certification?

Yes, NVQ is competency-based. Passing the written exam is necessary, but candidates must also pass a hands-on practical assessment supervised by a TVEC examiner to get certified.

What refrigerants are covered under NVQ Level 4?

The exam covers R134a and modern low-GWP refrigerants like R1234yf, focusing on pressure relationships, safe recovery, evacuation, leak detection, and environmental regulations.