Go to the hardware store and buy weather stripping. It is really inexpensive and is a tape so goes on easy.
Insulate the gap with PUF or thermocol.Contact an AC Mechanic……….
you can buy a seal kit at the hardware store. explain your situation to one of the clerks
put a soft siding around your door frame
You could just hang a blanket over the door…
They have this weatherproofing tape that you put in the door frame to provide a more secure seal for your door. They also have stuff you can put on the bottom of your door.
Yes, if air is coming in around the door, it shouldn’t be. It means the weather stripping is worn out or maybe even missing. Any hardware store will have a variety of styles to choose from. You can get it in plastic, metal, foam, and rubber. the sticky foam stuff works well and is easy to put up (may need to be re-done every couple of years though). If you know someone to ask for help, then that would be great otherwise the better hardware stores should be able to instruct you as well. It’s pretty easy. I you have more questions, feel free to email me too.
visit your local home supply store and talk to a salesperson about sealing around your doors AND windows. you will need specific equipment.