Auxiliary HVAC Control Assembly

Vehicles with automatic front and auxiliary HVAC systems will communicate back and forth over Keyboard Data Display (KDD) circuits. The HVAC control module will send out a HZ signal over the driver HVAC control assembly clock signal circuit to the rear auxiliary HVAC control assembly & return a HZ signal on the driver HVAC control assembly signal circuit. Vehicles with the sunroof option will have the rear auxiliary HVAC control assembly removed. A manually operated auxiliary system will be installed instead. Yukon and Tahoe models will have an adapter harness installed in line due to vehicle length.