Ignoring a frozen coil or chipping the ice off
Ice is a symptom of airflow or refrigerant trouble, and running the unit frozen strains the compressor while the melt can flood the drain pan. Chipping ice bends the soft aluminium fins and can puncture the coil, converting a cleaning job into a major repair. Thaw on fan-only mode and diagnose the cause.
Booking the first service of the year in June
The whole country calls a technician in the same first hot week, so June brings the year's longest waits and least negotiable prices. A March or April service finds problems while the weather is forgiving and the trade is quiet. Pre-summer maintenance is the cheapest version of every repair you will otherwise buy in August.
Closing vents in unused rooms to save energy
On a ducted system, closed supply vents raise static pressure in the ductwork rather than saving money: airflow across the coil drops, icing risk rises, and the blower strains. If a room genuinely never needs cooling, the right answer is a damper adjustment at the unit or a zoning setup, not a shut grille.