Portable AC Window Vent Kits

Casement Window

Side-hinged windows that crank outward. A custom insert seals the opening so your portable AC exhausts hot air outside without gaps.

Awning/Basement Window

Top- or bottom-hinged windows often found in basements and utility spaces. The insert fits snugly in the opening to vent your AC cleanly outdoors.

Single/Double Hung Window

Vertical sliding windows where the sash moves up and down. A custom insert seals the opening so your portable AC vents efficiently.

Sliding Window or Door

Horizontal sliding windows and patio doors. The insert creates a tight vent opening while keeping the rest of the glass unobstructed.

Crystal-Clear Plexiglass

Our panels look like glass — clear enough to let natural light in while keeping hot air out. Far superior to wood, cardboard, or foam solutions that warp and deteriorate.

Custom Cut to Your Dimensions

Every insert is made to order for your exact window measurements. No more ill-fitting panels with drafty gaps — a precise snug fit every time.

Works With Any Portable AC

Compatible with all major portable air conditioner brands including Midea, LG, Whynter, Honeywell, and more. Universal hose connection points.

No Permanent Modifications

Install and remove easily without drilling, cutting, or damaging your window frame. Perfect for renters and homeowners alike.

Perfect Fit Guarantee

If your window insert doesn’t fit perfectly, we’ll remake it – free of charge.

Even if the measuring mistake was yours.

Email us at info@martinsonmanufacturing.com and tell us what needs adjusting. “Make the width ½ inch shorter.” “Tighten the height.” Whatever it takes. We’ll cut a new one and ship it the next business day.   

We don’t leave customers stuck with something that doesn’t work.

Step-by-step measuring video guides you

Universal hose design fits every AC unit

Every order reviewed before fabrication

If it doesn’t fit, we remake it for free

Clear Shipping Times. No Guesswork.

Every insert is custom-cut and shipped with clear timelines. Choose the delivery speed that works for you, standard shipping is always included.

UPS Ground

FREE

Typically 3–5 business days once shipped. Included with every order.

2nd Day Air

$45

Need it sooner? Upgrade to 2‑day delivery at checkout.

Overnight

$75

Our fastest option. Delivered the next business day after shipment.

Canada Shipping

$22

UPS Ground shipping to Canada. Import duties and taxes may apply at delivery.

Portable AC Window Venting Done Right

Portable AC units fail with the wrong window setup. This insert fixes that.

Martinson Manufacturing

Precision window inserts for non-standard openings.

Call Today 262-340-1418

Build Perfect Insert

Trusted by thousands of homeowners who needed a real casement window solution.

Find the Right Portable AC Window Insert for Your Window