1. Locate the wiper arm you wish to adjust.
This is the bracket connected to the wiper blade itself, not to the wiper motor.
2. There are two nuts on most E-150 wiper arms: a hexagonal one and an Allen-head one.
To tighten the arm (increasing the pressure), turn the hexagonal nut that's closer to the pivot clockwise; counterclockwise to loosen it.
3. On some models, there may only be one nut on the arm.
Tightening or loosening this nut will accomplish the same thing.
4. Tightening the nut makes the arm push the blade with more force, decreasing the nut loosens the arm.
Be sure not to overtighten, or you could damage the nut, arm, or windshield.
5. Once you have the desired pressure, release the arm.
It will lock back in place.
Make sure to test your wiper arm adjustment before driving in rain or snow.
This will ensure that your wiper blades are working properly and clearing your windshield adequately.
