That first blast of air when you switch on your AC should feel fresh and cool—not make you wrinkle your nose. A bad smell from your air conditioner is a common complaint in Kolkata's humid climate, and the type of odour tells you a lot about what is going wrong inside.

Here are the most common AC smells, what causes them, and how to get rid of them:

1. Musty or Mildew Smell (Mold on the Coils)

This damp, "dirty socks" smell is the most common AC odour.

  • The Problem: The evaporator coil and drain tray stay damp from condensation. In humid weather, mold and mildew thrive on this moisture and the dust trapped on the coil, releasing a musty smell every time air blows across them.
  • The Fix: A deep jet wet servicing flushes mold and grime off the coils, blower wheel, and drain tray. Running the AC in fan mode for a few minutes before shutting it off also helps dry the coil.

    • 2. Sour or Stagnant Smell (Clogged Drain Line)

    A sour, swampy smell often comes from standing water.

  • The Problem: When the condensate drain line clogs, stagnant water collects in the drain tray and starts to smell. Bacteria breeding in this water gets pushed into your room by the blower.
  • The Fix: We pressure-flush the drain line and disinfect the drain tray to clear the stagnant water and bacteria.

    • 3. Burning or Plastic Smell (Electrical Fault)

    This is the one smell you must take seriously.

  • The Problem: A burning, hot-plastic, or gunpowder-like smell can mean overheating wiring, a failing fan motor, or a burnt PCB inside the indoor unit.
  • The Fix: Switch the AC off at the MCB immediately and do not run it. Our technicians inspect the motor, capacitor, and circuit board to find and repair the overheating component before it becomes a fire risk.

    • 4. Stale or Smoky Smell (Dirty Filters)

    A dull, stale smell usually points to neglected filters.

  • The Problem: Air filters trap dust, smoke, cooking odours, and pet dander. Once saturated, they release these trapped smells back into the room every time the AC runs.
  • The Fix: Rinse the filters under running water, dry them completely, and refit them. Clean them every 15 days during heavy use.

    • Book a Deep AC Cleaning in Kolkata

    If your AC smells musty or sour no matter how often you clean the filters, mold has likely built up deep inside the coil. Book a same-day doorstep deep AC servicing with Appliance Service Kolkata for only ₹299 (completely adjusted in your repair bill). Call us at +91 8240528725 today!