vent air on windsheld

I've got a '94 that is blowing air on the windsheild only. I read a long time ago that it was usually a vacuum leak to the controller? I was hoping someone could point me to any areas to look before I started to look myself. Any info will be of great help.
TIA,
Alan

The vacuum leak isn't necessarily to the controller. It could be anywhere. Look especially for leaks in the line that goes along the right inner fender, beneath the battery tray, to the vacuum canister behind the front bumper. Battery corrosion often eats that line up. If you've had some hard knocks, check the canister, too. It can crack, and if the mounting tabs break, they can leave a hole. If everything there looks good, check for pulled hoses on the vacuum motors to the heater flaps.