Mini HVAC System

1. Background

During my AvenueE program back on Sep, 2025, my teammates and I were tasked to constructed an automation that can assist the drivers when they operation their vehicle. Before selecting our project, our team brainstormed several ideas to improve vehicle safety and comfort:

• Pressure plate to sense users within the vehicle when locked, then set off an alarm outside
• Assisted parking system
• Proximity sensor
• More advanced signal lights
• Automated HVAC
• Legal speed limit detection

2. Weighted Decision Matrix

To choose the final topic, we created a weighted decision matrix.
Each idea was scored on several criteria, and each criterion had a different weight:

• Time to Implement (weight 5)
• Team Expertise (weight 2)
• Impact on Safety (weight 3)
• Impact on Efficiency (weight 2)
• Estimated Implementation Cost (weight 2)

The scores and totals are shown below.

The Automated HVAC idea received the highest total score (52), so we selected it as our final project.

Selected Topic: Automated HVAC

3. Project Overview

The idea is to keep the interior at a safe and comfortable temperature by automatically turning on cooling when the cabin gets too hot, instead of making the driver suffer in a “baking” car when they return. We built a proof-of-concept prototype using an Arduino and basic electronic components, with the long-term goal of integrating a similar system into real vehicles.

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4. Team Roles

Our project was a team effort. Each member contributed in different areas:

• Ryan Huynh

• Helped setting up and wiring the circuit on the breadboard
• Design the outer case / enclosure for the prototype
• Test and choose the thermal thresholds for when the fan should turn on or off

• Alfred Tsang

• Focused on coding the Arduino and implementing the control logicd
• Worked on debugging issues with the code and hardware interaction
• Contributed to the in-person presentation and explanation of the system

• Steven Clark

• Created and organized the slides for our presentation
• Helped with coding parts of the Arduino program
• Led the online presentation, explaining the project to the audience

5. My Role in the Project

In this project, I contributed to both the hardware setup and the practical design of the Mini HVAC system. My main responsibilities were:

• Setting up and wiring the circuit

I helped connect the temperature sensor, LCD display, fan, and power lines on the breadboard.
This included tracing the internal bus lines on the breadboard, choosing the correct Arduino pins, and making sure each component received the right voltage and signals without causing shorts.

• Designing the outer case / enclosure
  I worked on the physical housing that covers and protects the components.
  The case makes the prototype look more organized and easier to handle, while still allowing airflow for the fan and clear visibility of the LCD display.

• Finding a suitable temperature threshold
  I helped test and choose the temperature at which the fan should turn on and off.
  By experimenting with different values, we found a threshold that makes the system respond when the cabin feels noticeably warm, but without turning the fan on and off too frequently.

Overall, my contributions helped ensure the system was wired correctly, protected by a clean enclosure, and calibrated to react reliably during our demo.

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6. Problem and Motivation

On hot days, the interior of a parked car can quickly become much hotter than the outside air. This can lead to:

• Discomfort when people first get into the vehicle.
• Potential heat-related health issues in extreme conditions.
• A more frustrated and distracted driver.

In cold weather, people face the opposite problem: the interior is freezing, and they must wait for the cabin to warm up before feeling comfortable. A smarter HVAC system can help in both situations by conditioning the interior before the driver enters.

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7. Proposed Solution

Our solution is a Mini HVAC / Automatic Cooling System that monitors the vehicle’s interior temperature and compares it to a desired setpoint:

• The driver chooses a comfortable temperature.
• If the cabin gets more than a certain amount above that setpoint, the system automatically turns on cooling (the fan).
• Once the temperature returns to the comfortable range, the fan turns off.

In a full vehicle implementation, the same logic could also control a heater in cold weather and interface with the car’s existing HVAC system.

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8. Prototype Implementation

We built our prototype using an Arduino Uno and an electronics kit.

Main hardware:

• Arduino Uno (or compatible board)
• Temperature sensor
• Small DC fan (represents the vehicle’s A/C)
• LCD display to show temperature and status
• Breadboard, resistors, jumper wires
• Power from a USB cable or battery

How the prototype works:

1. The temperature sensor continuously measures the “cabin” temperature.
2. The Arduino reads this value and compares it to a setpoint.
3. When it’s too hot, the fan turns ON.
4. When it cools down, the fan turns OFF.
5. The LCD shows the temperature and status.

You can imagine replacing the small fan with a real car blower and A/C compressor, and putting the sensor in the actual vehicle interior.

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9. Control Logic

The system is a simple form of closed-loop control. It keeps checking the temperature and reacts when it moves too far away from the comfort range.

A simplified version of the logic looks like this:

loop:
  read currentTemperature

  if currentTemperature >= setTemperature + threshold:
    // Too hot – turn cooling on
    fan = ON

  else if currentTemperature <= setTemperature:
    // Back to target or below – turn cooling off
    fan = OFF

  // repeat forever

Demo