Motor service

Power window and engine maintenance

A window can stop working for one reason or another.

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Sometimes the fault is electrical, such as a bad power window switch, blown fuse, bad relay, or a loose or damaged wire. Other times the fault is a bad window motor or a broken part in the window regulator mechanism that raises and lowers the window.

The window regulator components inside the door usually include a small electric motor and a window regulator. The motor and regulator can usually be replaced separately, although both require removing the interior door panel to replace parts. Replacement typically takes about an hour, but may require an extra set of hands to hold the glass while the pieces are aligned and maneuvered into place.

The electric motors that drive the power windows are compact and powerful, and are similar to the motors used in power seats. OEM engines can cost between $100 and $300 or more, depending on the application (imports and luxury vehicles are generally more expensive).

On some vehicles, such as late model MINI Coopers, the window motor brushes can develop dead spots after four or five years of service due to the windows lowering and raising each time the door is opened.

This allows for a perfect seal, but all the extra movement also shortens the life of the window motor. Ford uses a similar setup in later Mustang models.

The regulator assembly that raises the glass is mechanical, and wears out over time, whether it is motorized with a motor or manual with a crank. Window tint on some vehicles can potentially cause additional stress on the engine and governor.

Some regulators use a steel cable and worm gears to lift the window, while others use a toothed plastic belt or a plastic band with teeth for the same purpose. Steel cables rarely fail, but plastic belts and bands often become brittle with age and exposure to heat, and can crack and fail, especially in cold weather.

On some applications, the plastic belt or strip can be replaced separately without having to replace the entire governor mechanism.

The plastic bushings and tracks of the window regulator mechanism can also be subject to wear, causing misalignment or binding as the window moves up and down. This can cause the glass to seal poorly with wind noise and/or water leaks.

The regulator assembly is usually bolted to the inside of the door frame and attaches to the bottom of the glass. Regulators can be relatively simple and compact, or large and complex. OEM replacement regulators (if available) can cost anywhere from $150 to $600 or more depending on the vehicle.

For applications that are over 10 years old, OEM parts may no longer be available. Fortunately, there are spare parts available for many applications.

Related items that a customer might need when replacing window regulator components include new weather stripping for the door, or weather stripping adhesive or sealant to repair loose or leaking gaskets.