If your AC runs but does not cool, start with the basics: Cool mode, a lower set temperature, a clean filter and a clear outdoor unit. If those are fine, the cause is often a dirty coil, a weak capacitor or low gas from a leak, which a technician should test.
An AC that runs but does not cool is frustrating, especially in the middle of a hot, humid Thane summer. The cause is often simple. Work through this list from easiest to hardest.
1. Wrong mode or temperature
Check that the remote is in Cool mode, not Fan, Dry or Auto-fan, and that the set temperature is clearly below the room temperature. Also check that no timer or sleep mode has changed the settings.
2. Dirty air filter
A clogged filter restricts airflow, so the cooling coil cannot move cold air into the room. Slide out the filters, rinse gently under running water, let them dry completely and refit them. Do this every few weeks in season.
3. Doors, windows and heat load
Open doors, gaps around windows, afternoon sun and heat from kitchens or electronics all fight the AC. Close the room, use curtains and give the AC time to pull the temperature down.
4. Blocked or dirty outdoor unit
The outdoor unit gets rid of the heat. If it is clogged with dust, leaves or hemmed in by a wall, or its fan is not turning, cooling suffers. Make sure nothing is blocking it and that the fan spins. Do not hose a running unit and do not put your hand near the fan.
5. Dirty evaporator or condenser coils
Dust and grime on the indoor and outdoor coils reduce heat transfer. A professional jet-wash service cleans them properly. Read our guide on AC service types and cost.
6. Low refrigerant (gas leak)
If the filter and coils are clean but cooling is weak, low gas is a common culprit. Signs include ice on the pipe, hissing noises and a long, weak cooling cycle. A sealed AC should not lose gas, so there is a leak to find. See our guide to AC gas refill cost for what to ask before paying for a top-up.
7. Weak or failed capacitor
The capacitor helps the compressor and fan motors start. If the outdoor fan runs but the compressor does not, or the AC hums and clicks, a weak capacitor is likely. It is a common and relatively inexpensive repair, but should be done by a technician.
8. Faulty thermostat or temperature sensor
If the sensor misreads the room temperature, the compressor may switch off early or not start. This often shows up as the AC cycling erratically.
9. Compressor or PCB problems
If everything above is fine, the cause may be a failing compressor or a control board fault. These need a proper diagnosis and a clear quote before you decide on repair.
Quick safe checklist
- Cool mode, low set temperature, timer off
- Clean and dry the filters
- Check the outdoor unit is clear and the fan is spinning
- Check the MCB or plug point
- Close doors and windows, block direct sun
When to stop and call a technician
- Ice on the pipe or indoor unit
- Water leaking inside. See our guide on AC water leakage
- Burning smell, tripping MCB or sparks
- Outdoor unit not starting, or loud grinding
- Still not cooling after a clean and the basics
Prevent it before summer
Book a service before the first heatwave, clean filters regularly, keep the outdoor unit clear and do not wait for a complete failure. Small issues are cheaper to fix early.
AC repair in Thane, Kalwa and Mulund
Our technicians visit your home, test the AC properly and give you a quote before starting. See our AC repair service or message us on WhatsApp.