WARNING: This page is about a different car, the 2019 Kia Soul EV. However, it is still accessible from the selected car via links, so may be relevant.
FATC: Sends AC/PTC power request to VCU when driver demands cooling/heating (AC SW).
A/C load is controlled within the power range allowed by VCU.
BMS: Provides usable battery power and SOC data.
VCU: Sends final FATC allowed power by using the battery information and FATC requested power data.