Why Is My AC Not Cooling? 10 Common Reasons & Solutions

An AC that isn't cooling during a hot Hyderabad afternoon can be incredibly frustrating. Before you panic, check these 10 common causes and how they can be fixed.

1. Dirty Air Filters

This is the number one cause of poor cooling. Dust restricts airflow, preventing your AC from circulating cool air. Clean your filters once every two weeks.

2. Incorrect Thermostat Settings

Ensure your remote is set to Cool Mode (snowflake icon) and not Fan or Dry mode. Set the temperature to a realistic 24°C for efficient cooling.

3. Clogged Outdoor Condenser Fins

The outdoor unit rejects the heat from your room. If the metal fins are covered in dirt, mud, or leaves, the heat exchange fails and the compressor overheats and shuts down.

4. Low Refrigerant Gas

Refrigerant is required to cool the air. Low gas levels (due to a leak) lead to slow cooling, frost on pipes, and eventual compressor failure.

5. Faulty Compressor Capacitor

If you hear a humming sound from the outdoor unit but the compressor doesn't start, the capacitor is likely dead. This is a quick and cheap replacement.

6. Blocked Evaporator Coils

Dust bypassing the filters deposits on the indoor coils. This insulating layer stops the refrigerant from absorbing heat from the air.

7. Faulty Thermistor / Sensor

If the AC sensor detects incorrect room temperatures, it will turn off the compressor prematurely before the room is cooled.

8. Undersized AC for the Room

A 1.0 Ton AC cannot cool a large 250 sq. ft. living room. Calculate your room size: under 120 sq ft needs 1.0 Ton, 120-180 sq ft needs 1.5 Ton, and above 180 sq ft needs 2.0 Ton.

9. Faulty PCB (Control Board)

The motherboard coordinates operations. Relay or microprocessor failure on the PCB can stop power from reaching the outdoor compressor.

10. Compressor Failure

The most expensive part of the AC. If the compressor windings are shorted or the mechanical pump is seized, it must be repaired or replaced.