I have a 2018 eco diesel Laramie. When trying to change the air flow to the defrost it will not change. I changed the actuator and the hvac control module behind the glove box. Did not work. Dealership says it is the heater control module 68158081AC but can’t tell me where it is located. I have searched the net and looked everywhere for it. Under the seats, all over under the hood and on every inch of the frame. One diagram says it should be on a bracket with the upper nox sensor and particular matter sensor. No bracket. Nox sensor is mounted to frame by itself. Any help locating it would be very appreciated. Winter will be here soon!!