Power windows are very common and a convenient accessory, until they break. Many people assume the power window motor must have failed. Surprisingly this is not the most common problem.
Power window motors are a lot better than they were just a few years ago. Advances in electric motor technology has greatly increased their reliability. A very small motor normally rotates a worm gear attached to the motor armature. The worm gear rotates a driven gear. (click any image for much larger view)
These motors are easy to test with a simple volt meter. If there is voltage and ground at the motor when the switch is pushed and it does not run, the motor is likely bad. If there is no voltage and/or ground, the problem is in the electrical feed. This could be the fuse, a bad switch, a relay or even a cut wire.
The driven gear attaches to the regulator drive gear, many times using drive rollers. These rollers allow for any slight misalignment, smooth window travel and quite window operation. They can also become brittle and break. When the drive rollers break, the motor will run, but the window will not go up or down.
If the regulator drive gear can be seen and does not turn, even though the motor is running, the likely fault is with the drive rollers. Drive rollers can often be replaced at a much lower cost than the window motor. This is particularly true on many older Ford products.
Converting the rotation of the motor into vertical window motion is the task of the window regulator. In the past most regulators were gear driven with arms. Small wheels rolled in the tracks and the arms would push the window up in a parallelogram fashion. These regulators were robust and gave very little problem. They were also a bit heavy and expensive to build.
In recent years many manufacturers have converted to cable type regulators. With the cable regulator a wire cable is fed though a drive mechanism, turned by the motor. A series of plastic pulleys guides the cable. A regulator carriage attaches to the cable and to the window glass and slides on the regulator track.
This system is light and cheap to produce, but is also quite fragile. Broken cables and pulleys are very common. These regulators are also non-repairable and must be replaced as an assembly when they fail.
The regulator normally attaches to the door shell with rivets. Felt and rubber channels guide the glass up and down in the opening. Keeping these channels clean and occasionally lubricating with dry silicon spray can greatly reduce regulator breakage.
When the regulator does break, the interior door panel must be removed. The rivets that attach the regulator to the door and to the window glass must also be removed. After removing the old regulator the new one is put in place and reattached with special rivets.
Power window repair is a bit tricky and many folks prefer to have it professionally done. AGCO is equipped to diagnose and repair any power window issue your vehicle may have. AGCO, it’s the place to go.
