Mercedes X166 Rear Window Lifter Regulator Motor Adjuster Left N/S A1666700004

Mercedes X166 Rear Window Lifter Regulator Motor Adjuster is an original window lifting system component designed for installation on the rear driver's side. Thanks to its factory design, it ensures proper operation of the window mechanism, stable window guidance in the tracks, and predictable interaction with the vehicle's electrical system, which translates into comfort during daily use.

Specifications and technical data

• SKU: A1666700004
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1666700004
• Substitutable numbers: A1666700004, A 166 670 00 04
• Location on the vehicle: Rear, Left
• Category: Window Motors & Regulators

Purpose and function in the vehicle

The presented component belongs to the Window Regulators and Motors category and is responsible for controlling the movement of the rear left window in the Mercedes X166 body. It is mounted in the rear section of the body, on the left side, where it works with the guide mechanism and the window control system.

Its tasks include:

• ensuring smooth raising and lowering of the rear left window,
• maintaining a stable window position at the desired level,
• working with factory window control switches and the comfort system.

Construction and fitment for Mercedes X166

The regulator with motor has been designed specifically for the X166 body architecture, which means matched mounting points and appropriate operating geometry in the rear left door. As a result, installation is straightforward, without the need for structural modifications.

Original manufacturing ensures:

• compatibility with factory wiring and connectors,
• proper fitment with the window guide mechanism,
• maintenance of the window system operating parameters specified by the manufacturer.

Condition and service application

The component is offered in used condition, making it an attractive solution for service repairs where the priority is combining original quality with reasonable costs. This type of part is suitable both for replacing a damaged motor or regulator and for comprehensive door restoration on the rear left side.

In practice, using a used, original regulator with motor allows you to:

• restore full functionality of the rear left window control,
• maintain the consistency of the electrical system with other body components,
• reduce repair costs while maintaining factory specifications.

Benefits of choosing an original window regulator

By choosing this rear left window regulator and motor, you gain a component designed specifically for the given body model, which minimizes the risk of installation and operational issues. Proper fitment to the rear left door translates into stable window operation, reduction of unwanted play, and correct functioning of comfort features.

If you are planning a comprehensive repair or upgrade of the door and window area in your Mercedes and need other elements from the same group, such as drives, guides, or complete lifting mechanisms, check the available parts in the Mercedes Window Regulators and Motors category.

Technical support and part selection

When choosing a used window system component, it is worth approaching the cost-effectiveness of the repair consciously and comparing different service solutions. It may be helpful to read practical tips on selecting used and refurbished parts – you can find them in the article Refurbished or used original – which part to choose for repair?.

For drivers interested in a broader context of operation and maintenance costs of premium class cars, the material dedicated to BMW power units may also be useful, available in the blog post BMW E90 faulty engines: check what can ruin your budget!, which shows how conscious component selection affects long-term vehicle maintenance costs.