So im having kind of a strange issue, for a long time my defrost would blow only thru the front vents but now it’s reversed. Nothing blows out of the front vents, everything blows out of the top vents. Anyone have an idea on what the issue could be?

 

Sounds like a blend door related issue.

 

'Could you explain? I dont know what that is

 

Blend door(s) is(are) irrelevant to the outlet selection for airflow. Blend doors only pertain to the temperature of the outlet air - that is, they control whether the air is warmed or not.

There are, however, mode selection doors in the plenum that control inlet and outlet selection. The doors, on trucks newer than 2003, are electrically operated under the climate control module. Possible faults would include the control module, the actuator/motor(s), or a physically jammed or broken door. Careful observations need to be made to better understand what is and is not working correctly so the list of possible causes can be narrowed down.

 

Regardless of whether you have EMTC or DATC, Item 1 below is the door that controls the airflow to the defrost vents, panel vents, or floor. This is your problem area and is likely the actuator has failed. Luckily this actuator can be reached just above the throttle pedal.