Note the conditions
Record outside temperature, road speed and how long the vehicle has been running when cooling changes. Details like “cold on the highway, warm at idle” are more useful than “A/C not working.”
Avoid repeated untested top-ups
Adding refrigerant without understanding why charge was lost can lead to repeated service and may leave another fault unresolved.
Book before the system stops completely
Early A/C inspection can identify declining performance before a hot-weather trip. If airflow is weak rather than warm, say so in the request.