hi gang. new to the site and already asking for help! 1988 dakota 3.9 auto 4x4. my question is, what controls the heat and air cond. controls as far as moving from defrost to floor to panels etc. my blower works fine on all speeds but just in the defrost position. if you push the button for floor,panel mix etc. it still just blows on defrost. also, do you have to have the control set to panel to start the a/c? i know you have to push the button to engage the comp. and slide to cold side. another car i had you had to set it on panel then start comp. thats the only setting it would run on.was wondering if this was the same. its my first dodge newer than 77 and i know very little about them so far. any help is appreciated! thank you

 

Welcome! The engine vacuum controls the switching of air vents. It sounds to me like you have a vacuum leak. There is a link to the engine vacuum diagram in the FAQs section. As for the A/C comp, it can turn on in any position, and in fact it should be on when you are running the defroster, cause the defroster won't defrost if the air is not dry.