Sizing by room area alone
❌ Mistake: "120 sq ft = 1 ton AC." Everyone quotes this rule. It's incomplete.
✅ Reality: Sun exposure, ceiling height, and how many people use the room matter just as much. A west-facing room needs 20-30% more capacity than a shaded one the same size.
💸 The cost: An undersized AC runs flat-out 24/7 trying to catch up — noticeably higher bills, every season, for years.
Trusting the star rating without checking the year
❌ Mistake: Seeing "5 star" and assuming it means the same thing every year.
✅ Reality: BEE tightens star rating standards roughly every 2 years. A 3-star AC today can beat a 5-star AC from a few years back.
💸 The cost: Paying a premium for an "efficient" label that's actually outdated.
Not thinking about the outdoor unit until installation day
❌ Mistake: Buying first, figuring out outdoor placement later.
✅ Reality: A boxed-in outdoor unit with no airflow cripples even the best inverter AC — this matters more than brand.
💸 The cost: A poorly ventilated unit silently inflates your bill, with zero warning signs.
Never checking copper vs aluminium coils
❌ Mistake: Not asking — because it's rarely advertised.
✅ Reality: Copper conducts heat better and lasts longer. Aluminium is cheaper to make and corrodes faster, especially in humid areas.
💸 The cost: An avoidable coil repair bill within just a few years.
Chasing the biggest "% OFF" badge on sale day
❌ Mistake: Picking whichever AC has the loudest discount tag.
✅ Reality: A small discount on a unit that costs more to run every year isn't a deal — it's a trap.
💸 The cost: Over the AC's life, that "deal" can cost you far more than what you saved.