What Is a Power Moonroof?

by Chris Stevenson

In common usage, "moonroof" has replaced "sunroof," although the two are nearly interchangeable. A sunroof uses a solid panel to slide back or tilt up, to allow air and light into the vehicle passenger compartment; a power moonroof consists of electric controls that power an inbuilt tinted glass panel into an open-closed or tilted position on the vehicle roof.

Glass Panel

A moonroof panel generally consists of a square-shaped piece of thick glass that sits in the center of the roof. The glass can have a slight curved profile that follows the roofline, or it can be uniformly flat. The glass comes in various stages of sun tint, depending upon the make and model of the vehicle. Some moonroofs are equipped with chrome, one-way panels that reflect heat but let in light.

Moonroof Seal

Moonroof panels have a gasket ring that seals the glass against the roof frame, to protect against the intrusion of water and air. The gasket material can be made of silicone, EPDM-type rubber or brand materials. The pliable gaskets have a maintenance-free design and construction, requiring only periodic cleaning with a cloth and water. The gasket ring also serves as a noise damper, keeping the glass panel from vibrating in the channel tracks.

Tracks

Moonroof glass panels sit inside a double trackway system, which extends from the front of the glass edge, in the full closed position, to a distance at the rear of the roof structure, hidden between the headliner and roof skin. The tracks, usually made of lightweight metal, have water channels that lead to small drainage hoses. The glass panel slides back and forth on the tracks for either the open or closed position.

Motor

An electric 12-volt motor powers the moonroof glass panel, for either the open or closed position. Two cables, which connect to the motor drive gear, attach to each rear section of the glass panel. The motor winds the cables rearward to pull the glass open and pushes the cables to close the glass in a locked, forward position. The control for the motor is located near the driver's seat, in the form of a rocker button or toggle switch. The glass panel can be partially opened to any position.

About the Author

Chris Stevenson has been writing since 1988. His automotive vocation has spanned more than 35 years and he authored the auto repair manual "Auto Repair Shams and Scams" in 1990. Stevenson holds a P.D.S Toyota certificate, ASE brake certification, Clean Air Act certification and a California smog license.

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