Check Your Thermostat First
Ensure it's set to COOL (not heat or fan only), the temperature is set below room temperature, and batteries aren't dead.
Inspect the Air Filter
A clogged filter restricts airflow so severely that the system can't cool properly. Replace if dirty—this is the most common DIY fix.
Examine the Outdoor Unit
Is the fan running? Is ice present? Are there obstructions? Clear debris and ensure 2 feet of clearance around the unit.
Check the Circuit Breaker
Outdoor units have separate breakers. A tripped outdoor breaker means the fan runs inside but the compressor doesn't cool.
Frozen Evaporator Coil
Ice on the indoor coil indicates airflow or refrigerant issues. Turn off AC, run fan only to thaw, and call for service.
Low Refrigerant
Refrigerant leaks cause gradual cooling loss. If the system cooled less effectively over time, a leak is likely. This requires professional repair.