1. Essential Service Types General Servicing (Every 3–4 Months): Cleaning filters and coils to maintain airflow. Chemical Wash (Annual): Using specialized solutions to dissolve stubborn mold and grime. Chemical Overhaul: Full dismantling to fix persistent leaks or foul odors. Gas Top-up: Refilling refrigerant to restore cooling power. 2. Key HDB Regulations Certified Pros Only: Technicians must be BCA-trained for all HDB installations and external ledge work. No Dripping: Ens