DIY Project Automates Analog AC Unit with ESP32 and Stepper Motor

The Challenge of Analog AC

The author's rental apartment in New York City features an AC unit with only analog knob controls, lacking a remote or wall-mounted thermostat. This setup required manual adjustments, prompting a search for an automation solution.

DIY Automation Solution

A custom device was built using an ESP32 microcontroller and a stepper motor. This assembly attaches to the AC unit's control knobs, allowing for automated adjustments. The total cost for parts was around $15.

Integration with Home Assistant

The custom hardware communicates with a Home Assistant instance using MQTT. This integration enables the AC unit to be turned on or off based on temperature readings from a sensor in the room, providing smart control over the previously manual system.

Practical Implementation

The physical setup involves a jerry-rigged ESP32-controlled stepper motor coupled to an AC knob with a shaft coupler. The entire contraption is affixed to the AC's back-plane using an L-bracket and a binder clip, with cardboard padding for stability. This approach avoids permanent modifications to the rental unit.