The ARS-1 mini-split air conditioner controller is a unique product that solves the age-old problem of having separate day and night temperature settings on your mini-split air conditioners. The ARS-1 is a universal controller that works with most mini-split air conditioners (and some window-type AC units too), as long as the unit came with an IR / infrared remote controller. We use the remote control that came with the unit to “teach” those IR signals to the ARS-1 module. Once the ARS-1 “learns” those remote control codes, the ARS-1 will send those same signals to the indoor mini-split head unit changing the setpoint to the desired Day or Night temperature setting automatically base on the photocell sensor status. *Note: The ARS-1 is currently not compatible with the following brands of devices: Daiken, Mr. Cool, Innovair, Denali Aire, Cooper and Hunter. *Firmware Update Note: To update firmware on the TrolMaster's controllers and modules, you must use a Micro SD card that is 32GB or less capacity.