What do you mean by ‘cond’? Is this inside or outside the house?
Where is the cold coming in?
You need to find out where the drafts are then go about using a caulk or other insulating material to close the gaps. For outside walls you can use the foam covers or even the plugs in the outlets if not in use. Check the bottom of the door for a rubber gasket that touches the sill or floor lightly when closed. Check around the windows and then caulk if there is a draft coming in. You do not say if there is a basement or just one level so it is hard to give a real response. Maybe the insulation in the attic needs more depth.
I'm trying all those things and I hope it works.
You can buy insulated covers for air conditioners at any hardware store or on Amazon if that is what you are referring to.