Re: 2003 Grand Cherokee A/C vent problem
Welcome to the garage.
The manual system uses a vacuum operated mode door actuator. This actuator is failsafe (so without vacuum) in the defrost position. Vacuum is taken from the engine intake.
There is probably a loose or worn through vacuum line under the hood
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
Monroe Reflex shocks /
Pirelli Scorpion ATR 245/65/17/
Transgo reprogramming shiftkit.