Air Conditioning Guide: Types, Cost & Efficiency

Central air conditioning: Whole-house cooling via ductwork. Outdoor condenser + indoor evaporator coil (on the furnace). Most common for homes with existing ductwork. Cost: $3,000-$7,000 (installed, replacing existing).

Mini-split (ductless): Individual indoor units + outdoor compressor. No ductwork needed. Cost: $1,500-$4,000 (single zone), $5,000-$12,000 (multi-zone). Excellent for additions, garages, and homes without ducts. Can also heat (heat pump models).

Window AC: Single-room cooling. Installs in a window. Cost: $150-$700. BTU range: 5,000-25,000. Best for: apartments, single rooms, supplemental cooling.

Portable AC: Single-room, freestanding. Vents through a window hose. Cost: $250-$700. Less efficient than window units. Loud. Best for: temporary cooling, rooms where window units can't be installed.

Heat pump: Heats and cools (AC mode in summer, heat mode in winter). Same technology as central AC but reversible. Cost: $4,000-$10,000. Most efficient option for combined heating and cooling.

Central AC (installed): Replacing existing: $3,000-$7,000. New installation (with ductwork): $5,000-$12,000+. Condenser only: $2,000-$4,000.

Mini-split: Single zone: $1,500-$4,000. 2-zone: $3,000-$6,000. 3-4 zone: $5,000-$12,000.

Window AC: Small (5,000-8,000 BTU): $150-$350. Medium (8,000-12,000 BTU): $250-$500. Large (12,000-25,000 BTU): $400-$700.

Operating cost per month (summer): Central AC: $100-$300. Mini-split: $50-$150 (per zone). Window AC: $30-$80 (per unit).

Repair costs: Refrigerant recharge: $200-$500. Capacitor: $150-$400. Compressor: $1,500-$3,000 (often means replacement). Contactor: $100-$300. Fan motor: $200-$500.

Efficiency (SEER2): Minimum standard: 14-15 SEER2 (depends on region). Good: 16-18 SEER2. Excellent: 20+ SEER2. Each SEER point saves roughly 5-7% on cooling costs. A 16 SEER unit saves ~15% compared to a 14 SEER unit.

Sizing: 1 ton per 500-600 sq ft (in moderate climates). 1,500 sq ft: 2.5-3 ton. 2,000 sq ft: 3-4 ton. 2,500 sq ft: 4-5 ton. Proper sizing requires a Manual J load calculation. Oversized AC: short-cycles, poor humidity control, wastes energy. Undersized AC: runs constantly, can't keep up on hot days.

Energy saving tips: Set thermostat to 78°F when home. Use a programmable or smart thermostat. Seal ductwork leaks (saves 20-30%). Shade windows on the south and west sides. Insulate attic. Keep condenser clear of debris. Change filters regularly.