I have a 2008 3500 All the controls and vents work when it is first started, for the heater and AC. I have the glove box out and I can see the heat / AC controller work when I turn the know. I can also see the vent door working above the blower motor. Every thing works great until you drive for about 45 minutes then nothing works. You don't get heat or AC and the vent doors and controllers stop working. I have read all the threads about blower vents doors broke. this is not the problem, if it sits and cools down it is back to normal and you get Ac and Heat and you can direct it to any vent. Yes the blower works on all the different settings, I have cleaned the drain line and it drains condensation so I know it is open. Any suggestions, Thanks for the help.

 

The one door that you see working over the blower is the FRESH/RECIRCULATE door.
There are two other functions, the BLEND door that mixes the hot and cool air as you adjust it and the mode door that chooses HEAT/VENT/DEFROST

Do tell, after the time period when it stops working.... pull over, pop the hood (with defrost selected) and report if the AC Compressor clutch is engaged.
Does the larger pipe from the firewall feel cool like a cold can of beer?

Does the blower stop working also and you just feel ambient temperature regardless of the position of the temperature ****? [red or blue]

Hey, when you get this figured out, please return and tell us (tell the next guy, looking) what you discover and what you do to fix it, even if you end up taking it to a shop or dealership
Cheers!

 

FabricGATOR , this is my farm / go to the lumber yard truck / city truck, and I will be out of pocket for the week, give me until next week and I will make a run to the city and do some tests.

Thanks for the help.

 

FabricGATOR, here are my results, again the fan blows at all speeds and all settings from floor recirculate to defrost only, there is no air coming out of any of the vents after 45 minutes of driving. The outside temp the day I drove it was 40-60F. When you turn the temp controller on the dash you can see the gate arm move up and down when you change from cold to hot. I have the glove box out and the top vent door stays shut regardless of where you turn the **** that changes the airflow even the recirculation settings all the way to the left. Under the hood both of the lines for the AC were covered in frost. they temped at 29.9 F. Let me know what else you need to know. Thanks for the help.




when you turn it to hot the right this arm pulls up when you turn it to cold the left the arm goes down when it is having the problem

 

I put a ac pro tester on the system and found it was low on freon and needed a charge and added 1.5 small cans of freon to the system along with a little stop leak additive,. Made a trip to town and the system lasted over a hour but on the way back quit blowing out of the vents again. When I got back checked the freon level again and it had not changed. still showed charged.

 

Stopped blowing, or stopped blowing cold?

 

My Ram 2500 4x4 5.9l diesel auto is doing the same thing. I can be driving along and everything this working like it is suppose. But then I can start to feel the force of the air coming out of the vents decreasing until it stops coming out, but you can still hear the fan running. Then if I turn the fan all the way off for about 20 minutes or so, and turn it back on, it is working just fine until it starts it all over again. I just got back from a trip from Fl to Az and back and it did that the whole way. What I have done to it so far is, replaced all blend doors (with alum doors) and actuators, heater core and evaporator, and ac controls. I've had it apart twice so far and guess I will have it apart again. Any help would be greatly appreciated.

 

Does yours sound like it is full of pressure from the fan and none of the gates can move? questions? how do the Actuators work? I have talked to a lot of car people about this problem, one asked if i had a vacuum leak? Not knowing how everything works, and you have had it apart, could we be dealing with a vacuum leak that runs one of the doors or actuators, which is allowing a something to close and what I am thinking building up pressure not allowing anything to blow out? I did not see any vacuum hoses going into the fire wall.

 

Yes, it sounds like it is building pressure. With the fan on high, I can hear it going like crazy, but nothing coming out anywhere. The actuators are electric. At first, I thought they were vacuum like my Tj is. But, once I got it apart, I found that they were all electric.

 

and you replaced the actuators, is there a way the voltage could drop and allow them to release? I am in Utah and have about a month to figure this out before it snows and I need to the defroster to work.

I have have the glove box out I am thinking about drilling a hole in the vent door for the recirculating gate given mine does not have a cabin filter I can see it under the dash to see if it is a pressure problem. Thoughts? Figured I could always plug it if it does not help.