98 Ram truck has an issue with the ac system, when vacuum drops when accelerating up a hill for instance, the cold air in my face drops out and I get what feels like room temp air, possibly from the defrost vents, then comes back on cold in my face when I back out of gas. My actuators, and I think there are three of them, are the vacuum type not electric. Can anyone tell me by the description I gave which actuator it is and the location, or if it's an actuator problem at all, maybe a broken vacuum line somewhere? Thanks for any input.