Start with settings
Make sure the thermostat is set to cooling and the fan setting is appropriate. If the fan runs without active cooling, the air may feel warm even when the blower itself works.
Check what you can safely see
Look at the filter and accessible vents. If the outdoor unit is not operating, the system is icing, or breakers keep tripping, avoid repeated resets and arrange diagnosis.
Professional causes require testing
Electrical faults, refrigerant-side problems, failed components, and control issues should be diagnosed with proper tools rather than guessed from symptoms alone.
Safety note: If you smell gas, see smoke or fire, suspect carbon monoxide, or believe there is an immediate safety danger, leave the area as appropriate and contact the relevant emergency or utility service. Do not treat an active safety emergency as a routine HVAC appointment.