10 Most Common AC Problems and Their Solutions

From water leaks to compressor failures, split and cassette AC systems can run into various issues. Here is a troubleshooting guide for the 10 most common AC problems, their causes, and how to resolve them.

1. Water Dripping from the Indoor Unit

Cause: A clogged condensate drain line due to dust and algae buildup, or an incorrect drain pipe slope.
Solution: Flush the drain pipe with pressurized water or clear it manually. Correct the piping slope if it has sagged.

2. AC Unit Not Turning On

Cause: Burnt power contactor, dead remote batteries, blown PCB fuse, or a tripped MCB.
Solution: Check the circuit breaker and remote batteries. Call a technician to inspect the PCB fuse and electrical wiring.

3. Lukewarm Air Instead of Cool Air

Cause: Low refrigerant gas, dirty condenser coil, or a faulty compressor capacitor.
Solution: Clean the outdoor unit. If that doesn't help, have a technician check the gas pressure and capacitor values.

4. Ice Formation on the Evaporator Coil

Cause: Clogged air filters blocking heat exchange, or very low refrigerant gas levels.
Solution: Turn off the AC, let the ice melt, and clean the filters. If the ice returns, check for gas leaks.

5. Constant On/Off Cycling (Short Cycling)

Cause: A dirty air filter restricting airflow, a faulty thermostat sensor, or an oversized unit.
Solution: Clean filters and verify sensor values. Ensure the AC is sized correctly for your room.

6. Strange Vibrating or Grinding Noises

Cause: Unbalanced indoor blower wheel, loose casing screws, or worn motor bearings in the outdoor fan.
Solution: Tighten any loose screws. Blower fan wheels and motor bearings need professional replacement.

7. Foul Musty Odour from Vents

Cause: Mold, mildew, and bacteria breeding in the damp environment of the indoor drain pan.
Solution: Perform a deep chemical cleaning of the evaporator coil and disinfect the drain tray.

8. Remote Control Not Working

Cause: Dead batteries, damaged infrared receiver on the AC display panel, or a faulty remote.
Solution: Change batteries. If it still doesn't work, test with a universal AC remote or call for PCB sensor repair.

9. Outdoor Unit Fan Not Running

Cause: Failed fan motor winding, or a dead fan run capacitor.
Solution: Replace the fan motor capacitor or the fan motor assembly.

10. Circuit Breaker Trips Instantly

Cause: Direct short circuit in the compressor winding, or a grounded fan motor.
Solution: Do not try to turn it back on. Call an emergency technician immediately to test for electrical grounding.