1. Clean the filters
Dust on the indoor filters is the #1 reason a unit cools poorly. Pop them out, rinse with water, dry completely, refit.
2. Clear the outdoor coil
Leaves, lint and dust on the condenser coils make the system work harder. A garden hose at low pressure clears most of it.
3. Check for refrigerant leaks
If cooling has slipped year-on-year, gas may be low. Don’t top up blindly — ask a technician to find the leak first.
4. Test the drain line
A blocked drain causes water to leak inside the room. Flush the line with vinegar to keep algae out.
5. Inspect the capacitor and fan
A capacitor that’s about to fail will start to bulge. Catch it before the compressor refuses to start mid-July.