The air is cool, but not cold
A gradual drop in cooling is one of the most common signs of an A/C problem. Low refrigerant is possible, but so are condenser airflow issues, compressor performance problems and blend-door faults. A proper A/C inspection checks the system before refrigerant is added.
Cooling changes with driving speed
If the system cools on the highway but warms up at idle, note that detail. Fan operation, airflow and pressure behaviour can help narrow the cause. Weak air from the vents may point to a cabin filter or blower issue rather than refrigerant.
Do not ignore new noises or smells
Clicking, grinding or a musty smell deserves attention. Turn the system off if a severe mechanical noise begins and contact the shop. Include the vehicle year, make and model plus when the symptom appears in your service request.