The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.
Car Problem Reports
Dodge Ram 2500 HVAC Air Flow Switching to Defrost When Accelerating
Dodge Ram 2500 Problem
Average Mileage: 151,375 mi (100,000 mi - 188,500 mi)
Visitor, 1996 Dodge Ram 2500
switches to defrost under acceleration
Air flow switches to defrost when accelerating or pulling up hill. Have not found a fix as of now