Hi,

Recently, I have this issue with the A/C in my Ram. When its running and I
step on the gas pedal, a hear a noise like a flap closing and it the cool air
is diverted instead of out of the vents, its coming out where the defoster
would. But when I left off the gas the flap open/closes and the air comes out
the vents.
Any ideas ??

Thanks
Bruce

this is a VERRY common isue with the dodge trucks, since the heat/air controls are ran off of engine vacume.

your isue coudl be from one of two things; first, there is a check valve that, if I remember correctly, is on the engine side of the fire wall, and is in the vacume supply line that goes to the vacume switch behind the dash. there is a new version of this check valve available from the dealership, and I think there was even a TSB about it quite a wile back.

or, the other thing it could be is just a vacume leak someplace. however, it may be tricky to track down, because you'll need to check all of the vacume lines.

http://dodgeram.info/tsb/1996/24-01-96a.htm

Could this possibly cause the engine to run hot? I have the same issue but the engine seems to run hot. I have had the fan replaced and put in a new thermostat. The temp gauge goes almost all the way over but doesn't overheat if I don't run the air... cut the air on and it overheats!