THE DO-IT-YOURSELF GUIDE TO HVAC CLEANING AND MAINTENANCE! With normal AC maintenance expenses somewhere in the range of $150 and $425, having your AC unit tuned up by a professional may not be in the budget. While you can’t tackle every issue, here are a few do-it-yourself tips you should know to keep your AC unit sound: CHECK AND REPLACE YOUR AIR FILTERS The most significant thing you can do at home is to check your air filter. A dirty air filter makes your AC unit less productive and causes strain on its working parts.