A charge-verification tool is used with a charge-verification system to diagnose and remedy a charge condition. The charge-verification tool includes a device having a controller configured to communicate with a system controller in the charge-verification system and a display configured to display measurements and instructions to an installer. The device is a user interface and is configured to provide communication between the installer and the system controller in the charge-verification system. The controller prompts the installer to input charge-verification system information including refrigeration line length and diameter. The controller receives a subcooling temperature calculated by the system controller and determines whether the subcooling temperature is between a threshold and a target subcooling temperature. The controller displays an amount of charge to add to the charge-verification system based on whether the subcooling temperature is between the threshold and the target subcooling temperature.