Dor-O-Matic door closers use hydraulic pressure to close external and internal doors that must be kept shut for safety reasons. Inspecting the unit and making a few simple adjustments is often enough to fix most problems. The door closer may operate at the wrong speed or slam the door, which will require adjustment or repair. Most work can be completed in under 30 minutes with basic hand tools.
Have an assistant stand guard and make sure no one attempts to open the door while you are working on the mechanism. Climb up on a stepladder with slotted and Phillips head screwdrivers with the door closed.
Tighten up the screws that hold the closer to the door and frame with the Phillips head screwdriver. Loose screws will cause the unit to move during operation and sometimes interfere with the arm. Make sure the screw at the elbow joint in the arm is tight, along with the connections at the closer and the door.
Locate the main speed valve screw on the underside of the closer near the door. The screw is the one nearest the center of the unmarked pair. Turn the screw clockwise with the slotted screwdriver to increase the main closing speed or counterclockwise to slow it down. Repeat the process with the latch speed screw, the one next to the main speed valve. The latch speed screw controls the speed of the closer over the last few inches of travel.
Adjust the backcheck valve, if one is present, to control how heavy the door feels when it is pushed back open while closing. Turn the screw marked "BC" beside the main speed and latch speed controls clockwise to increase force or counterclockwise to reduce.
Spin the screw marked "DA" for Delayed Action clockwise to increase the amount of time the door stays open before closing. Turn the screw the opposite direction for the door to close quicker. Not all closers are equipped with this option.