DTC U0164: Lost Communication With HVAC Control Module: General Description
WARNING: This page is about a different car, the 2017 Kia Soul EV. However, it is still accessible from the selected car via links, so may be relevant.
CAN communication is the circuit consisting of LOW line, HIGH communication line and two 120Ω resistances (installed in EPCU and CLU) that allows control modules (EPCU, LDC, VCU, BMS, TCS, AHB, EWP, FATC, TMU, OBC, etc.) to exchange information to each other.