Yes, testing the air conditioner immediately after installation while the technician is still on-site is strongly recommended, as it allows any installation errors to be identified and corrected on the spot without requiring a second service call. Run the unit for at least 15 to 30 minutes at its full cooling setting and check that the room temperature drops noticeably, that the airflow from the indoor unit is strong and consistent, and that no unusual sounds, vibrations, water leaks, or error codes appear during operation. Confirming that the unit is functioning correctly before the technician leaves protects you as a consumer and ensures that any issues discovered during the test run are addressed as part of the original installation job rather than billed as a separate service.