Causes and Fixes U0164 Code: Lost Communication with HVAC Control Module

How to diagnose and fix U0164 Code: Lost Communication with HVAC Control Module A U0164 Code is set when the main computer (ECM/PCM) cannot communicate with the HVAC control computer. The HVAC Control Module (HVACCM) receives inputs from sensors, some hardwired directly to it, some over the BUS communications system. These inputs allow the module to control the interior temperature of the vehicle, in this case for front only or both front and rear passengers. The CAN BUS (Controller Area Network) is a protocol that allows the ECM, PCM, ECU, HVACCM and other computer modules to communicate with each other. Possible Causes of a U0164 Code: Issues with Power Source (Bad Battery - Alternator Charging Issues - Bad Ground) Blown Fuse (ECM/PCM/ECU/BCM Fuses) Wiring Harness Open or Short Computer Module Has Failed By using this information, the user assumes all risks of use.