As many will know , the mechanism of regulation of various settings between user and conditioner , is via a remote control , which is based on sending infrared signals . To investigate the function of these signals , I recommend you look at the post in reference to Chapter 10 of the Arduino design becomes simple
Obviously , the code of an air conditioner , vary depending on the model and according to the manufacturer. For this reason, as the first phase of the work , you must do the procedure that is called reverse engineering , that is to obtain the codes for your device , using the sensor TSOP1738 .
Once you have obtained the codes for your air conditioner, we're almost to complete "the work ." You need to use a small program that simplifies setting the code to insert into the Arduino , and you can send the various encodings . These codes can be set by the user through a simple web page , with or without protection.
As you have read in the " Hardware requirements " , I wrote that you need two Arduino , the main reason is that the sequences of bits to be sent to the air conditioners are too large to be contained in a single device , which among other things should also take care of the part of management commands that will be transmitted via the Internet.
In practice there will be a device that will take care of the part webserver and the other to send IR signals . The other reason that prompted me to do this project with two device , is that you can safely use Raspberry PI for the management of the webserver , so definitely improve the look and feel of the web page.