With the exception of the commands to toggle the energy saver feature and the front panel lights, all of the commands encode a full system state instead of just a single command, ensuring the remote stays in sync with the air conditioner. This state is encoded in five bytes containing information on the power state, sleep state, system mode, fan speed, set temperature, and the remote temperature sensor reading. The final byte is some sort of checksum, which I have not been able to figure out. The remote is based around a 4-bit microcontroller with 64 bytes of RAM, a Sino Wealth SH66P51A, so the checksum calculation must be something simple. Based on its behavior to changing input, it seems to involve XOR operations, but it does not always behave like a simple XOR. As I haven’t been able to figure out the functional form of the checksum calculation, I can only send commands that I have recorded from the remote. This isn’t too much of an issue as I recorded all of the possible commands except for those involving the remote temperature sensor feature (and the timer since I didn’t care about it). Recording all temperature sensor commands would be very difficult as it only transmits once every three minutes and one needs to get the sensor to report all values. I was hoping to emulate the remote’s temperature sensor using a higher quality sensor, but, alas, I can’t without the functional form of the checksum. It turns out that the bit order of the data needs to be reversed for the checksum calculation. The checksum can be calculated by reversing the bit order of the five data bytes; adding them, truncating the result to 8 bits, and subtracting the result from 2⁸; and reversing the bit order of the subtracted result. Below is a Python function to do the checksum calculation.

def calc_checksum(bytes):
    # Reverse bits for each bytes
    bit_reversal = []
    for i in bytes:
        bit_reversal.append(int('{:08b}'.format(i)[::-1], 2))
    # Calculate checksum
    checksum = 2**8 - sum(bit_reversal) % 2**8
    # Return bits to original order
    return int('{:08b}'.format(checksum)[::-1], 2)

Detailed information on the individual data bytes, values recorded from the remote, and Python code for emulating the remote with a USB Infrared Toy is available here. If anyone figures out the checksum calculation, please let me know.

Edit 2016-04-23: Tim Chang figured out the checksum calculation and let me know via email. I updated the post to include the checksum calculation.

Edit 2016-08-17: Fixed description of middle pulse.