Development and Evaluation of Teaching Aids for Vehicle Air Conditioning Systems in the Automotive Technology

Development and Evaluation of Teaching Aids for Vehicle Air Conditioning Systems in the Automotive Technology

Mohd Syazwan Che Manshor¹, Siti Faizzatul Aqmal Mohamad Mohsin²

¹Department of Mechanical and Manufacturing Technology, Seri Iskandar Vocational College

²Department of Engineering Technology, Faculty of Technical and Vocational, Sultan Idris Education University

DOI: https://dx.doi.org/10.47772/IJRISS.2025.908000392

Received: 14 August 2025; Accepted: 21 August 2025; Published: 13 September 2025

ABSTRACT

Air conditioning is an important part of the vehicle. However, its hidden location on the dashboard of a vehicle makes it difficult for lecturers to effectively deliver practical lessons. The limitations in the practical work prevent students from clearly visualizing the whole air-conditioning system of a vehicle. Therefore, teaching aids for lecturers have been developed by constructing a fully accessible vehicle air conditioning system outside of the vehicle. This improvement ensures that lecturers and students have full access to the vehicle air-conditioning system of the vehicle during training sessions. The ADDIE model has been used as a basis for the design process of the teaching aid project. The project utilizes an air compressor, condenser, condenser fan, expansion valve, cooling coil, blower fan, 1 HP AC motor, hoses, high- and low-pressure pipes, compressor switch, and condenser fan switch to create a standalone air conditioning system that operates without using fuel or vehicle engine. Six subject matter experts evaluated the system’s functionality by conducting performance assessments and leakage tests. The development of the teaching aid has proved to be effective in providing convenience to lecturers in delivering lesson content while enabling students to experience effective learning.

Keywords: Automotive technology, vehicle air conditioning system, teaching aid, vocational colleges, TVET

INTRODUCTION

The air conditioning (AC) system functions to provide ventilation and cooling within the cabins of both domestic and commercial vehicles. It is required to regulate the internal temperature in the cabin to ensure the comfort of vehicle users (Zhang et al., 2018). The usage of AC systems in vehicles is essential, particularly in Malaysia. This is due to Malaysia’s humid tropical environment with an average temperature of approximately 30 ̊C. However, observational studies on temperature trends in Malaysia indicate an increase each year (Saimi et al., 2020). Thus, air conditioning maintenance in the automotive sector represents a critical area that requires attention to ensure the smooth operation of vehicle AC service. Not only that, the emergence of electric vehicle (EV) technology has also brought significant transformation to the automotive industry. EVs require more efficient AC systems for automotive applications (Zhang et al., 2018). Hence, the automotive air conditioning service centre is obligated to provide optimal service to customers, as service operations, especially those involving automotive products, are central to business success (Khonglumtan & Srisattayakul, 2023).

Problem statement

The role of Technical and Vocational Education and Training (TVET) institutions is becoming more crucial in developing essential skills for specialized fields. Vocational Colleges (KV) in Malaysia are a part of the education system that focuses on TVET, which integrates both theoretical and practical components. The objectives are to cultivate skilled and semi-professional workers to meet industry demands. A total of thirty-three programs are offered across Vocational Colleges in Malaysia to elevate the visibility of TVET in the education sector (Ministry of Education, 2025). One of the programs offered is Automotive Technology.

The teaching and learning process of the vehicle AC system is an essential module for Automotive Technology students.

However, the positioning of the AC system within the vehicle dashboard makes it difficult for students to visualize, understand, and perform practical work, especially in AC system maintenance.  To enable effective student learning, a tangible teaching aid project for vehicle’s AC system which is located outside the vehicle, is required. This is in accordance with the concept of work-based learning practiced in Vocational Colleges, particularly among students in Automotive Technology program. Work-based learning incorporates real-world skills into the students’ learning process (Mazlan et al., 2025). Diagnostic skills and the ability to detect and repair a vehicle’s system faults are crucial skills for automotive students (Haron & Ahmad, 2018). However, only hands-on practical experience during the teaching and learning process can cultivate these skills.

Many existing TVET programs fall short of industry requirements, leading to a mismatch between graduates’ skills and market demands (Qianyu et al., 2024). One of the main challenges for TVET institutions providing skills-based education is the substantial investment required to ensure infrastructure development aligns with industry advancement (Shahran, 2024). Nevertheless, research indicates that TVET institutions continue to have difficulties pertaining to insufficient learning materials, inadequate training facilities, deficient training equipment, limited classroom space, and inefficient lecturing practices (Had Sabtu et al., 2016). This shortcoming needs to be addressed effectively to produce competent graduates who meet industry standards, especially in the automotive service-related field. The provision of well-developed infrastructure, especially for carrying out practical work, can enhance students’ learning effectiveness and assist lecturers in the teaching process (Mohamad et al., 2022; Muhammad et al., 2019).

The lack of infrastructure for conducting skills-based practical work also negatively impacts the competencies of both lecturers and students. Shaharom et al. (2024) stated that instructors who are not competent in conducting practical sessions will adversely affect students’ skills, which in turn will impact the employability of students in skill-based fields (Mustafa, 2024). The employability of graduates in the TVET field depends on their ability to meet the skill demands of the industry. Therefore, the provision of teaching aids in skill-based fields is highly encouraged to ensure that lecturers have the necessary and precise tools to teach, while students can effectively acquire practical skills.

The maintenance of a vehicle’s AC system requires energy that can only be supplied by starting the vehicle’s engine, which involves fuel combustion. In the context of this study, concerns regarding the need to purchase fuel for each vehicle involved in AC maintenance practical sessions lead to wastage. Lambert and Jones (2006) noted that the mechanical compressor used in AC systems can increase vehicle fuel consumption by 12 percent to 17 percent, depending on the vehicle’s size. At times, the fuel that is purchased and prepared is often insufficient due to unforeseen factors that occur during the practical sessions, causing the teaching and learning process to be disrupted and postponed.

Therefore, this study aims to develop a vehicle’s AC system that can be accessed externally without dismantling the dashboard and does not require fuel to operate. The development of this project also aims to fulfil the need for teaching aids at the diploma level in Automotive Technology, especially for the courses DMA4073 Automotive Air Conditioning Service and DMD2122 Vehicle Electrical and Electronic Systems, notably in Vocational Colleges

METHODOLOGY

Analysis Phase

The development of the External AC System (EACS) adopts the ADDIE Model approach, which consists of five main phases, namely Analysis (A), Design (D), Development (D), Implementation (I), and Evaluation (E). These phases are illustrated in Fig. 1 below:

Fig. 1 Description of project development for each phase in the ADDIE Model

Design Phase

The analysis phase is the first stage of the ADDIE model. The analysis phase involved the identification of challenges faced by students and teachers in understanding and identifying the entire component of the vehicle’s AC system. The lack of teaching aids for teachers is also one of the challenges encountered in conducting the theory and practical sessions.

Side View Top View Front View Actual View

Fig. 2 The illustration of EACS

Development Phase

The development phase of the EACS project is based on the sketch in Figure 2, which is then refined with dimensions and the identification of necessary components. Figure 3 shows the development of the EACS along with the components.

Side View Top View Back View

Fig. 3 The EACS project

The EACS project, as in Fig. 3 was built using the same AC system components as in actual vehicles as Fig. 4.

Fig. 4 The Automobile Air Conditioning System

In real vehicles, the AC system requires engine power to drive a pulley, which is connected to both the engine and the compressor via a drive belt, in order to function. However, to develop user-friendly, accessible, and easy-to-maintain teaching aids, this project does not use a real vehicle engine. Instead, an alternating current motor is used to replace the engine power needed to operate the AC system.

Normal vehicle electrical systems typically use direct current to operate, but EACS uses alternating current power to run the motor. There are differences between the use of alternating current and direct current in vehicle electrical systems and domestic electrical systems. Using alternating current in the AC system could potentially damage its components. Therefore, converting alternating current to direct current is essential for the developed teaching aids to function properly. To generate direct current for EACS, a vehicle alternator rectifier is used to convert alternating current to direct current. The electrical power output from the alternator is directed to the battery storage, which then serves as the power source to activate the electrical components of the EACS.

The EACS operates similarly to the real vehicle AC system but in a more user-friendly, accessible, and maintainable version. The vehicle AC system works in a closed-loop cycle involving pressure and refrigerant states to cool the air. There are four main components in the vehicle’s AC system, namely the compressor, condenser, expansion valve, and evaporator.

The compressor draws in low-pressure refrigerant and compresses it into a high-pressure, high-temperature gas. The high-pressure gas is then sent to the condenser, where it changes into a mixture of liquid and gas suitable for flowing to the expansion valve. The expansion valve regulates the flow of refrigerant from the condenser to the evaporator by reducing its pressure and temperature. When the high-pressure refrigerant passes through this valve, it undergoes a sudden drop in pressure, producing a low-temperature mixture of liquid and gas ideal for cooling.

The valve also adjusts the flow amount based on system needs, ensuring efficient cooling and preventing evaporator freeze-up. This ensures the cooling coil does not freeze, allowing cold air to be delivered through the air conditioning vents.

The cooling coil, located inside the cabin, absorbs heat from the cabin air, lowering the cabin temperature. Cold air is then blown through the blower and distributed via air vents to cool the interior of the car.

Implementation Phase

This phase involves the involvement of six experts in Automotive Technology to determine the validity and functionality of EACS. These experts are lecturers in Automotive Technology with over six years of pedagogical experience. Validating the EACS at this stage is crucial to ensure its successful operation and practical implementation. Identifying malfunctions or errors in the developed EACS is crucial at this stage to ensure its effective application in delivering and providing both theoretical and practical instruction for the diploma courses DMD4073 Automotive Air Conditioning Service and DMD2122 Vehicle Electrical and Electronic Systems at Vocational Colleges.

Evaluation Phase

The evaluation process is conducted in two stages, namely the validity and the usability of EACS.

Validity of EACS

The quantitative approach was used to find out the degree of agreement among experts about the developed external AC system. The CVI score was evaluated according to the cumulative score from the expert. A total of six experts from Vocational Colleges were chosen based on specific criteria, namely expertise, qualifications, experience, and field. All the experts have over six years of experience in the automotive field. Selecting subject-matter experts to determine the project’s validity is essential for ensuring accuracy in meeting specific objectives (Bougie & Sekaran, 2019). These experts aim to test the EACS project and validate its content. Table I delineates the backgrounds of the experts involved in this study.

TABLE I The backgrounds of the experts involved in assessing the project’s validity

The CVI was calculated according to the cumulative score from each expert based on an assessment of the EACS content. CVI calculation is a widely accepted method for assessing content validity. CVI was used because this method is more focused on measuring the degree of agreement among the experts. Experts were provided with a questionnaire during the assessment session to validate the EACS.

A relevance rating of 1 (relevance scale for 3 or 4) or 0 (relevance scale of 1 or 2) must be recoded before the CVI is calculated. The formula applied is based on the item-level content validity index (I-CVI). The ratio of content experts rating a relevance rating of 3 or 4 is calculated as the number of agreed items divided by the total number of experts involved (Polit et al., 2007). Table II shows the content validation with I-CVI analysis for the developed project. The scale-level content validity index (S-CVI/Ave) was assessed to determine the proportion of the relevance as evaluated by all experts. The S-CVI/Ave was computed using the formula of the sum of I-CVI divided by the number of items. The universal agreement (UA) score assigned a value of 1 when there is 100% consensus among experts; otherwise, the UA score is assigned a value of 0. Table 2 presents the outline of the EACS content in automotive technology subjects, along with the validity values assigned to the EACS project by each expert.

TABLE II The relevance ratings for the EACS from six experts

According to Lynn (1986), the acceptable I-CVI value for a panel of six to eight experts is at least 0.83. In this study’s findings, the I-CVI obtained from the six experts was 1.00. Therefore, this project has high validity as a teaching aid for the vehicles’ air conditioning system.

Usability of EACS

The project’s usability was assessed by the functionality test of the air conditioning system and the gas leakage test.

Functionality Test of EACS

This test was conducted to verify that the air conditioning system in this project is operational. The project operates by using a belt installed to drive the pulley compressor to generate the required power for the external AC system. Table 3 presents the time schedule for the functionality of the external air conditioning system during practical sessions.

Table III The relevance ratings for the EACS from six experts

As indicated in Table III, this project is able be powered on, and the air-conditioning system operates effectively for 20 minutes and able to generates cool air at a temperature of 5 ̊C before shutting down. The EACS project inability to operate for an extended period due to the type of motor used. The 1HP AC motor used as the power source is unable to supply adequate power for the system to operate over a prolonged duration. Nonetheless, in terms of practical work session, the project effectively capable for demonstrating the actual operational functionality of a vehicle’s air conditioning system.

Air Conditioning System Leak Test

This leak test is conducted to ensure that the EACS does not experience any system leakage. Leakage in the air conditioning system can reduce the efficiency of the constructed system. Therefore, leak testing can be carried out using three methods namely, electronic leak detector, UV dye, and the soap bubble method. In the context of this study, the leak test was conducted using the soap bubble method. This testing process is important to ensure that refrigerants such as Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) are not released, as they can deplete the ozone layer and contribute to global warming (Daviran et al., 2017). Table IV shows that no gas leakage was detected at any of the component connections in the developed air conditioning system.

Table IV Air Conditioning System Leak Test

CONCLUSION

This study seeks to develop a project-based teaching aid for the maintenance of vehicle air conditioning within the context of automotive technology in TVET institutions, particularly vocational colleges. The development of the teaching aid, named External Air Conditioning System (EACS), is intended to address the demand for practical instructional resources and has demonstrated beneficial impacts on the functionality of the tool. EACS operates efficiently in delivering comprehensive explanations of the air conditioning mechanism within a vehicle. EACS also provides more substantive knowledge to enrich and engage students’ learning experiences. The EACS was engineered with a portable design, enabling it to be transported effortlessly during practical sessions. It facilitates educators in conveying lesson content more effectively. The development of the EACS offers exposure to external researchers in producing more economical and effective teaching aids that can be used by the students and lecturers especially in TVET sectors. It is suggested that the evaluation of the EACS project be expanded for use in various automotive-based related institutions so that the research findings can be compared, and further refinements can be made. The use of the EACS project among students showed a positive effect on students’ learning experiences. Therefore, it is hoped that this project can be expanded to the next phase in order to be refined and disseminated more widely in the automotive technology sector.

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