ESP32 DIY Air Conditioner with NTC Sensors

An experimental project using an ESP32 microcontroller to control a repurposed heat pump from a clothes dryer for room cooling. The system monitors temperatures using 10k NTC sensors, provides a web interface for control and monitoring, and includes safety and automation logic.

Features

• 📡 Wi-Fi Access Point: The ESP32 creates its own Wi-Fi network with a built-in web interface.
• 🌡️ Temperature Monitoring: 4 analog NTC sensors (10k) monitor:
  • Room temperature
  • Condenser coil temperature
  • Evaporator coil temperature
  • Compressor temperature
• 🎯 Adjustable Target Temperature: Set your desired room temperature via the web interface.
• 🔁 Automatic Cooling Logic:
  • Compressor and fans run until the room reaches the target temperature.
  • Compressor stops if the condenser temperature drops below 10 °C to prevent icing.
  • The evaporator fan keeps running for 10 minutes after cooling stops to dissipate remaining heat.
• 🔥 Safety Features:
  • Compressor cooling fan turns on if it gets too hot.
  • Compressor shuts off at critical temperature and resumes only after cooling down.
• 🖥️ Manual Relay Control: Toggle each relay manually from the web interface for testing or override.

Hardware Requirements

• ESP32 (WROOM module)
• 4x 10k NTC thermistors
• 4x ADC-capable GPIO pins
• 4x relay modules
• Repurposed heat pump (from clothes dryer)
• 5V or 3.3V power supply for sensors and ESP32

Pin Configuration

Function	ESP32 Pin	Description
Compressor temperature	A0 (GPIO36)	NTC thermistor
Condenser temperature	A3 (GPIO39)	NTC thermistor
Evaporator temperature	A6 (GPIO34)	NTC thermistor
Room temperature	A7 (GPIO35)	NTC thermistor
Compressor relay	GPIO16	Turns compressor on/off
Condenser fan relay	GPIO17	Controls condenser fan
Evaporator fan relay	GPIO18	Controls evaporator fan
Compressor cooler relay	GPIO19	Cools down hot compressor

How to Use

1. Upload the code to your ESP32 using Arduino IDE or PlatformIO.
2. The ESP32 creates a Wi-Fi network called ESP32-Climate (password: 12345678).
3. Connect to the network and open a browser at http://192.168.4.1.
4. View real-time temperatures, set your desired temperature, and control relays.

NTC Sensor Configuration

You can adjust the characteristics of your thermistors in the code:

#define BETA 3435           // Thermistor B-value
#define R_FIXED 10000       // Fixed resistor in voltage divider (ohms)