Next, press and hold down the ‘Reset’ button for 3 or more seconds and then release. Often, the button is quite small but should be labelled and can frequently be found beneath the digital display. In this way, where is the reset button on the Carrier air conditioning unit?you will need to locate the ‘Reset’ button on the air conditioner’s control panel. Press and hold the “Reset” button down for another 3 seconds - this time a light should flash on the display. Press and hold the “Reset” button down for 3 seconds and then release. How to Reset a Carrier Air Conditioner Unit Locate the “Reset” button on the air conditioner’s control panel.