Hey, welcome to the club-nothing like a summer sweatbox to motivate some wrenching. First off, don’t dive straight into refrigerant; that’s a fast way to turn your garage into a hazmat zone without the right gear. Start simple: Pop the cabin air filter (it’s behind the glovebox on most Civics) and see if it’s clogged with dust bunnies. A dirty one kills airflow like nobody’s business. Swap it for a $10-15 filter from AutoZone-no tools needed beyond your hands.
If that’s clean, eyeball the condenser coils up front (behind the grille) for leaves or bugs gunking it up; hose ’em gently with a garden sprayer. Tools? Just a basic screwdriver set and maybe some compressed air cans ($5). If it’s still weak, grab a cheap manifold gauge set (~$30 online) to check pressure, but YouTube a Civic-specific vid first to avoid guessing. Hit us with what year your Civic is for more tailored advice!