First, the thermostat. Sounds basic, but we walk into one or two houses a week where the system got bumped to HEAT or to FAN ON without anyone noticing. Confirm COOL, set 5° below room temp, and listen for the outdoor unit to start within 90 seconds.
Second, the air filter. A filter loaded with Texas dust can choke airflow enough that the evaporator coil freezes solid. If you see ice on the indoor unit or refrigerant lines, shut the system off, leave the fan on, and let it thaw for 2–3 hours before restarting.
Third, the outdoor unit. If the fan isn't spinning or the unit is humming without spinning, that's almost always a failed capacitor — a $20 part and a 15-minute fix for a tech, but a fire hazard to attempt yourself. If the unit is spinning and warm air is still coming out, the issue is likely refrigerant charge or a failing compressor — both call territory.
What we see most after those three: dirty condenser coil (we recover 10–20% capacity with a real coil flush), failed contactor, low refrigerant from a slow leak, or a control board issue. Any of those, we handle the same day with parts on the truck.
