AC Not Cooling? 7 Reasons Why & How to Fix It

It's the middle of summer, your air conditioner is running, but your room still feels warm. Sound familiar? You're not alone. AC not cooling is one of the most common complaints we receive at HUNAR — and in most cases, the fix is simpler than you think.

In this guide, we'll walk you through the 7 most common reasons your AC is not cooling properly, how to diagnose each one, and whether you need a professional AC repair technician or can handle it yourself.

1. Dirty or Clogged Air Filter

This is the #1 cause of poor AC cooling in India. Your AC filter traps dust, pet hair, and allergens. When it gets clogged, airflow is restricted — the evaporator coil can't absorb heat properly and cooling efficiency drops by up to 15%.

How to check:

• Open the front panel of your indoor unit
• Remove the filter — if it looks grey/black, it's clogged
• Wash with lukewarm water, let it dry completely, and reinstall

2. Low Refrigerant (Gas) Level

Refrigerant — commonly called AC gas — is the substance that actually cools the air. If your AC is low on refrigerant due to a leak, it simply cannot cool the room no matter how long it runs.

Signs of low refrigerant:

• AC blows air but room doesn't cool
• Ice forming on the copper pipes or indoor unit
• Hissing or bubbling sound from the unit
• Higher than usual electricity bills

3. Dirty Condenser Coils (Outdoor Unit)

Your outdoor unit releases the heat extracted from inside your home. If the condenser coils are covered in dust, leaves, or debris — which is very common in Indian cities — heat cannot escape efficiently, and cooling performance drops significantly.

Fix:

• Keep 2 feet of clearance around the outdoor unit
• Gently clean the fins with a soft brush
• For deep cleaning, book an AC service with HUNAR

4. Thermostat Set Incorrectly

Before calling a technician, check the basics. Many people accidentally set the thermostat to "Fan Only" mode instead of "Cool" mode. The fan runs, air circulates, but no actual cooling happens.

• Ensure mode is set to Cool (❄️) not Fan
• Set temperature to 24°C–26°C for optimal efficiency
• Check that the timer hasn't been set accidentally

5. Undersized AC for the Room

An air conditioner's capacity is measured in tonnes. If your AC is too small for the room, it will run continuously but never reach the desired temperature. As a general rule in India:

• Up to 120 sq ft → 1 Ton AC
• 120–180 sq ft → 1.5 Ton AC
• 180–240 sq ft → 2 Ton AC

6. Blocked or Leaking Air Ducts

For central AC or cassette units, blocked or leaking ducts mean cooled air never reaches the room. Signs include uneven cooling across rooms, weak airflow from vents, and a constant running compressor.

7. Faulty Compressor

The compressor is the heart of the AC. If it fails, the AC cannot cool at all. A faulty compressor is the most expensive AC repair — typically ₹4,000–₹15,000 depending on the brand and capacity.

Signs of compressor failure:

• AC runs but outdoor unit fan doesn't spin
• Loud clanking or banging noise from outdoor unit
• Circuit breaker trips when AC is turned on
• AC compressor doesn't start at all

When to Call a Professional AC Technician

Call a professional if:

• Cleaning the filter didn't help
• You suspect a refrigerant leak
• The outdoor unit makes unusual noises
• Your AC is more than 5 years old and hasn't been serviced
• Ice is forming on any part of the unit

HUNAR connects you with background-verified AC technicians across Mumbai, Delhi, Bangalore, Hyderabad, Pune, Chennai and more. Our technicians carry tools and spare parts for same-day AC repair.

AC Maintenance Tips to Prevent Cooling Problems

1. Service your AC at least once a year — ideally in March before summer
2. Clean the filter every 2–3 weeks during heavy use
3. Keep curtains closed during peak afternoon heat
4. Set temperature to 24°C–26°C — saves up to 6% electricity per degree
5. Use a ceiling fan alongside the AC — allows you to set temperature 2°C higher