Air Conditioner opening

Today I worked on the opening for the air conditioner. I used the center vent opening. This worked out well because the center vent cover wasn't original, it was galvanized metal, rusted, and broken.

I drilled out all the rivits holding the vent frame in.

The opening is 14x16 but the air conditioner boot is made for a 14x14 opening so I needed to close it in by 2". I cleaned up the opening and cut two strips of aluminum. Then I riveted the strips down, one on the front, one on the back. I used Dicor under the strips to seal them. Then I put Dicor liberally on every rivet and seam.

I test fitted the air conditioner on the opening and it fits perfect.