AC Not Cooling? 7 Common Reasons and What To Do
An AC that runs but doesn't cool is usually one of seven things: a dirty filter, low refrigerant from a leak, blocked coils, a faulty compressor, poor installation, a control fault, or a unit too small for the room. Most causes need a proper diagnosis — a few are safe to check yourself, others strictly need a technician.
7 reasons your AC isn't cooling
1. Dirty or clogged air filter
A blocked filter restricts airflow over the cooling coil, so the AC runs but cooling drops sharply. This is the most common cause and the easiest to check — remove the filter, rinse or vacuum it, and let it dry fully before refitting. If cooling doesn't improve, move to the next cause.
2. Low refrigerant from a gas leak
AC gas doesn't get 'used up' in normal operation — if levels are low, there's a leak somewhere in the line. This needs a technician to locate the leak, seal it, and recharge the correct gas quantity; handling refrigerant yourself is unsafe and won't fix the underlying leak.
3. Blocked or dirty outdoor/condenser unit
The outdoor unit needs clear airflow to release heat. You can safely clear leaves, dust and obstructions from around it yourself. But cleaning the condenser fins and internal coil properly needs a technician's tools to avoid damaging them.
4. Faulty compressor
The compressor is what actually cools the refrigerant — if it's failing or has tripped its overload protector, cooling drops or stops entirely. This is an electrical and mechanical component that should never be opened or tested by anyone other than a trained technician.
5. Poor or incorrect installation
Wrong indoor/outdoor unit placement, excess pipe length, or incorrect tilt on the indoor unit can all reduce cooling efficiency permanently, not just occasionally. If cooling has never been great since installation, a technician needs to inspect and correct the setup.
6. Thermostat or control board fault
If the AC runs, the fan spins, but the compressor never kicks in or cycles oddly, the thermostat sensor or control board may be misreading temperature. This is an electronics fault a technician diagnoses with proper test equipment, not a DIY fix.
7. AC undersized for the room
If the AC has always struggled on hot days, it may simply be too small for the room's size or heat load (large windows, top floor, many people). This isn't a fault — a technician can assess your room and advise honestly whether a larger unit or a second AC makes sense.
Straight answers before you book.
Is a non-cooling AC something I can fix myself?
Cleaning or replacing the air filter is safe to do yourself and resolves a good share of cases. Anything involving gas, the compressor, or wiring needs a trained technician — these aren't DIY-safe repairs and attempting them can make the fault worse.
How fast can W2 send someone to check my AC?
For most Bengaluru localities we offer same-day visits when you book before 4 PM. The technician diagnoses on the spot and gives a written quote before any work begins.
Will I be charged just for the visit?
Yes — a flat visiting charge applies for the diagnosis, shown live on this page, and it's adjusted against your bill if you go ahead with the repair.
Free diagnosis, written quote, 90-day warranty.
Visiting charge ₹350 — adjusted in your bill if you proceed. For full details, see our AC Repair & Service page →