Ford 1999 Wagon-Econoline Owner's Manual page 165

Maintenance and care
WINDSHIELD WIPER BLADES
Check the wiper blades at least twice a year or when they seem less
effective. Substances such as tree sap and some hot wax treatments used
by commercial car washes reduce the effectiveness of wiper blades.
Checking the wiper blades
If the wiper blades do not wipe properly, clean both the windshield and
wiper blades using undiluted windshield wiper solution or a mild
detergent. Rinse thoroughly with clean water. To avoid damaging the
blades, do not use fuel, kerosene, paint thinner or other solvents.
Changing the wiper blades
To replace the wiper blades:
1. Pull the wiper arm away from the
windshield and lock into the service
position.
2. Turn the blade at an angle from
the wiper arm. Push the lock pin
manually to release the blade and
pull the wiper blade down toward
the windshield to remove it from the
arm.
3. Attach the new wiper to the
wiper arm and press it into place
until a click is heard.
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