Just started winterizing sealing around the windows, doors and ACs. After I was done I noticed that it was ice cold around where the floor mouldings are in the front and back of the house. The walls and around the windows were the cold mouldings are aren't so cold.
Is this normal? Can I easily fix this?
Fix it, yes. Easily, depends on your definition.
Rim joist insulation might help. There's probably a gap in the insulation at the bottom plate. Hard to fix without removing the baseboard and opening the wall behind it. This way you see exactly what the issue is. A not so "exactly" solution would be to remove the baseboard and drill holes in the sheetrock wall and shoot in some slow expanding foam. I'd try 3-4 holes per bay. If it works, install the baseboard back. If not, see plan ,"A".