Hey all, new guy here, hoping to find some insight into my little AC problem. 04 QuadCab with about 176,000 on the clock, AC blows good and cold, after about an hour on the highway theres almost no air out of the vents. Switching from dash to floor will sometimes alleviate the problem. The fan is still blowing and what air comes out is cold, so I'm pretty sure the problem is vacuum, but I have no clue where to start. Is there a vacuum pump. How do I test this system? Any help is appreciated.

 

Mine does the same thing. I was thinking that its in the switche sending the wrong signal to turn the blower to a lower setting or the blower motor is going bad or blower motor resister I haven't looked into it yet
Its nice when your hauling a boat to Texas in 105 degree heat and the A/C isn't blowing good

I am not sure if dodge's have a cabin filter it may be dirty and also the heater core and the evaporator maybe clogged with dirt and not allowing air through it?