I have a 2001 Dodge Ram 1500, 5.2 L V8, 2 wheel drive with 118000 miles. I am having an issue with my A/C. It blows cold air, which in Houston is a great thing. However, whenever I hit the accelerator to pass someone or get up to speed, the air stops blowing through the vents and blows out of the defrost vents. Once I let off the gas, the air returns to the A/C vents. I have no idea what is wrong but I would love to fix this myself if it is possible. Thanks for your help.
I think that you will find that you have a vacuum leak in the vent control system. When the engine is idling or at road speed you have plenty of vacuum to over come any small leak, when you acclerate you loose manifold vacuum when the throttle snaps open, the vacuum accumulator may not have enough reserve to function due to the leak, vacuum drops and the valves that relly on vacuum to stay open close untill vacuum is restored. Hence the change from vents to screen. Now the tricky part, finding the leak. You will have to listen around all the vacuum controls, lines & valves, if the leaks is bad enough you will hear a hiss, these leaks can be very time consuming to locate so take your time and you should pick the leak up.