Hello,Have a question on a 2007 ford v6 base model mustang.When I turn on the ignition switch, if I turn the control knob to the right which is defrost or floor vents their is a clicking sound. But if I turn it to the left it doesn't click.Which actuator do I actually need to replace to stop this.I know the question has been asked before but your help will be greatly appreciated! Thanks in advance.