I have been having some trouble getting any air to come out of the vents after atleast 20 miles have gone by. It blows nicely and then after 20 miles or so you can barely feel anything come out of the vent. I thought it might have been a vacuum issue but I don't feel anything out of the defrost vents when it is doing this either. The fan always sounds the same, making a ton of noise but something is cutting all the air flow off. Any ideas? :confused:

I don't think so because it doesn't go to the defrost vents at all and it all stays ice cold. I am still waiting for another hot day B)

Heres another piece to the puzzle. It got hot today so I ran it and it did it again, reduced to half the flow. I felt everywhere and it wasn't blowing anywhere but the two head vents I had open, just hardly blowing. BUT!, I set it on defrost for about 30 secs and it felt a little bit stronger, so I went back to head vents and the thing was back to full flow.. So it's almost like the defrost door just needed to be reshut or something to seal off better but I don't understand why there is 0 flow through the defrost vents when it goes into that limp mode state. I would think there would be backflow. At least I found the little trick to make it work, supposed to be 93f tomorrow and 97f thursday, along with the wonderful humidity that Missouri is known for :mad

Hmmm... Vacuum leak under the dash, bad vacuum motor that is leaking or a bad vacuum selector fot the vent controller??? :confused:

Have you pulled and checked the fan blower motor resistor?.Its located on the bottom of the heater box inside the cab mounted with two screws,It will casue some of the symptoms your having.Also of note the Second Generation Dodges are NOTORIOUS for the A/C evaporator cores failing and causing the system to loose charge.In the 206,000 miles I have owned my truck I have had 3 installed(2 by Mopar under warranty and the last one by my local A/C man last year).When I did the last one we also did the heater core to be safe as I did not want to pull the dash and air box a second time......Andy