Clogged temp sensor vents can also cause problems for the auto climate control unit. These are located behind both of the front grab handles above each front door. Pry out the small plastic devices with a hole in the middle. Inside each opening is a FRAGILE thermister device that helps regulate the cabin temp. CAREFULLY vacuum out all the dust that has accumulated inside the opening. There's a small fan behind the thermister that draws in the air. One of mine started buzzing one day and sounded like a hugh bumble bee inside the headliner.