This topic has been covered a few times on here before, so you might try using the search button for other suggestions.

From my own experience, the one that has made the biggest difference for me (former smoker) is sing an ozone generator. I think you might be able to rent these. A lot of fire mitigation places use them after a fire. However, it's important to note that you should not be home when using the machine. Ozone in high quantities is dangerous to your lungs. When I tried this, I set the machine near one of the air intakes for the heat/AC and leave it on full blast for a few hours (letting the AC cycle on and off a few times). This allows the ozone to be carried through the AC itself as well as all of the vents and rooms of the house.

Be sure to open all the windows and doors and let everything "air out" as much as possible before reentering or spending any time in the house. You'll want the ozone to dissipate as much as possible before you go back in.

Since you've already tried painting and vinegar, the problem may be in the AC itself (especially if it's worse after you turn it on). You might contact an AC repair center and see if they have any suggestions.

Good luck! If you find something that works, remember to tell us about it on here!

You may have to invest in a air purifier. Or...you may have to call in a professional cleaner. Make sure you tell your cleaner that you are trying to get rid of the smell of smoke in your house so that they are sure to use the appropriate cleaner.
Good luck!