AC Features Explained: Which Ones Are Worth Paying For

• Dry or dehumidify mode runs the compressor gently with a low fan to pull moisture out without over-cooling — ideal for humid monsoon days in Mumbai, Chennai or Kolkata. Nearly every AC has it.
• Sleep mode raises the set temperature by a degree or two over the first hours of the night, which matches how the body cools during sleep and saves power.
• Turbo mode runs at maximum capacity for fast pull-down. Use it for ten or fifteen minutes, then return to normal.
• Eco or energy-saver modes cap power draw. They trade some cooling on hot afternoons for a lower bill.

Standard AC filters are mesh dust filters. PM 2.5 filters, as on Daikin's current range and Blue Star's IC718QCUS and ID318DNUHC, catch a share of fine particles in the recirculated air, and activated carbon layers reduce some odours. They are not HEPA-grade, and an AC is not built to push air through dense filter media.

Ion technologies such as Panasonic's nanoe-X treat the air rather than filtering it. For measurable PM 2.5 reduction in a polluted city, use a HEPA air purifier alongside the AC.

• 4-way swing moves air up-down and left-right, which helps in wide or L-shaped rooms.
• Auto restart returns the AC to its last setting after a power cut — essential where cuts are common.
• Timer switches the AC off after you fall asleep, or on before you get home.
• Digital display and hidden display are purely cosmetic; a hidden display is nicer in a dark bedroom.
• Gas leak detection warns when refrigerant is low, before cooling quietly fades — Voltas lists it on several models.
• Filter-clean indicator reminds you to wash the filter; a clogged filter is the most common cause of poor cooling.