How to Install a Window Air Conditioner Panel?

A window AC panel installs by attaching the accordion side panels to the unit, seating it in the window, and locking the sash down before securing everything in place.

For the full breakdown, see our best Air Conditioner Window Panel guide.

Installing a window air conditioner panel so it seals tight is a doable weekend job. The process hinges on one thing: the accordion side panels must attach to the AC first, not the window frame, so the unit carries them when lifted into place. This guide covers the correct order, common mistakes, and exact hardware steps from manufacturers like GE.

What You Need Before You Start

Measure the window opening before installing anything. You need both the width and height with the sash raised, because the AC and side panels must meet the frame on all sides to seal. Grab a tape measure and record the numbers.

You’ll also want a drill with a 1/8-inch bit, a screwdriver, and the screws that ship with the unit. GE specifies Type-A screws for the top mounting rail and Type-B screws for the side curtains and window lock bracket. One GE model uses four Type-A screws, another uses three, so check your manual for the exact count.

Plan for two people. Window ACs are heavy, and lifting one into place while someone else handles the sash is much safer.

Installing the Side Panels and Seating the Unit

Start with the window fully open. If your model has a top mounting rail, install it first with the Type-A screws. Apply weather strips to the window’s top and bottom edges and to the side curtain frames before sliding anything together, since you can’t reach those spots once the unit is in place.

Slide the accordion side panels onto the AC housing. Some models use screws, some snap into frames, and some slide in without fasteners—follow your hardware package. With panels attached, lift the unit by its base—never the front panel or control knobs—and rest it on the sill or support bracket. Center it before going further, since moving it once the sash is down is a fight.

Lower the window sash so it sits behind the upper flange on the AC. The sash should rest on top and help hold it in place. At this point, the AC should be level or tilted slightly outward, about 1/4 to 1/2 inch toward the exterior. That tilt lets condensate drain; a level or inward-leaning unit will pool water and leak.

Securing the Panels and Sealing the Gaps

Extend the accordion panels until they press against the window tracks. On models with pre-drilled holes, mark the spot, drill 1/8-inch pilot holes, and drive in the Type-B screws. Pilot holes stop the thin window frame from splitting.

Install the window lock bracket next. This metal piece bridges the sash and window stool to stop outside lifting. Most kits include one; if not, it’s worth buying. Home Depot’s guide recommends an L-shaped lock bracket attached with the provided hardware.

Finish by pressing foam weatherstripping around the unit and panel edges to block air gaps that let heat and bugs in. The strips applied earlier compress as panels extend, creating the seal—skip that step and you’ll feel the draft immediately.

On power: plug the AC directly into a grounded three-prong wall outlet near the window. GE lists this as a compatibility requirement, and extension cords are a fire hazard at window AC amperage. If the nearest outlet is across the room, have one installed.

Common Mistakes to Avoid

• Not measuring the window opening first. A unit that doesn’t reach the frame on both sides won’t seal no matter how much foam you add.
• Lifting by the front panel instead of the base. The plastic panel isn’t load-bearing and will crack.
• Leaving the unit level or tilted inward. You need that 1/4 to 1/2 inch outward tilt for drainage.
• Skipping pilot holes. Screws driven directly into window trim split the wood.
• Using an extension cord when the outlet is out of reach. Move the unit or add an outlet.

If you’re still shopping, the roundup of tested air conditioner window panels covers options that fit standard single-hung windows with minimal fuss.