AC Not Cooling?12 Fixes from a Real HVAC Technician
Your AC is running but the room stays warm? Here are the 12 most common causes — and exactly how to diagnose and fix them before you pay for a service call.
Why is my AC running but not cooling?
The most common causes are a dirty air filter, low refrigerant gas, or a failing compressor. Start by cleaning the filter and checking your thermostat mode. If the large copper pipe is not cold, you likely need a gas recharge.
These three issues account for over 70% of cooling complaints in the field. Always check simple fixes first before calling a technician.
Best AC in India — Top Rated ModelsIf your AC is not performing well, consider upgrading to a more efficient model. best AC models →
Quick Diagnosis
Select the symptoms you are seeing. We will tell you the most likely cause.
Step-by-Step Fixes
Ranked from easiest to most complex. Start at #1 and work your way down until your AC is cooling again.
What to do:
- 1Press the Mode button on your remote and ensure it shows 'Cool' or a snowflake icon.
- 2Set the temperature to at least 3–4°C below the current room temperature.
- 3If you have a smart AC, open the app and verify the mode has not been changed remotely.
Many service calls are resolved by switching from Fan mode to Cool mode. Always check this first.
Expert Insight
Based on real repair cases, low cooling is most often caused by refrigerant leakage, incorrect AC sizing, or a failing compressor capacitor. These three issues account for over 70% of the "not cooling" complaints we see in the field. Always check the simple fixes first — but do not ignore the warning signs that need professional attention.
When to Call a Technician
Some fixes are beyond DIY. Here are the situations where a trained HVAC technician is the safest and most cost-effective choice.
Refrigerant leak detected (hissing sound, oil stains, warm suction pipe)
PCB burnt smell or repeated error codes after reset
Compressor clicks but never starts — possible capacitor or compressor failure
Ice returns on coils within 24 hours after thawing and cleaning filter
AC is under warranty — DIY repairs may void coverage
Electrical work needed (capacitor, wiring, breaker replacement)
Average Service Costs in India (2026)
Preventive Maintenance Tips
Most AC failures are preventable. Follow this routine and extend your unit's life by 3–5 years.
Clean filters every 2 weeks
In dusty Indian cities, filters clog fast. A clean filter improves airflow, cooling speed, and energy efficiency by 15–25%.
Clean outdoor coils monthly
Use a soft brush or low-pressure water spray on the condenser fins. Dust storms in North India can cut cooling by 30% if ignored.
Check drain pipes quarterly
Pour diluted vinegar through the drain line to prevent algae and dust clogs that cause water backup and auto-shutdown.
Service before summer starts
Book a pre-season service in March. Technicians are less busy, parts are in stock, and your AC is ready before the first heatwave.
Keep outdoor unit shaded
A condenser in direct sun works 10–15% harder. Install a simple shade structure with 1 foot clearance on all sides for airflow.
Monitor voltage stability
If your area has frequent voltage dips, invest in a quality stabilizer. It protects the compressor, capacitor, and PCB from premature failure.
Tools You May Need
Most fixes above require basic household items. Here is the full list:
Multimeter
Check input voltage and stabilizer output
₹300–₹800
Fin Comb
Straighten bent condenser fins
₹150–₹400
Soft Brush
Clean dust from coils and filters
₹100–₹250
Garden Hose
Gently rinse outdoor condenser coils
Already owned
Screwdriver Set
Open indoor panel and outdoor electrical cover
₹200–₹500
LED Flashlight
Inspect dark areas inside outdoor unit
₹200–₹500
Choosing the right AC depends on multiple factors, including budget and room size. top air conditioners →
Common Questions
Quick answers to the questions we hear most often in the field.
The most common causes are: the remote is set to Fan or Dry mode instead of Cool mode, the air filter is completely clogged, or the refrigerant (gas) level is too low for the compressor to absorb heat effectively. Start by checking the remote setting, then clean the filter. If those are fine and the larger copper pipe (suction line) is not cold and sweating, you likely need a gas recharge — but only after the leak is found and sealed.
Still struggling with frequent AC problems? Explore the best replacement options. best AC models →
If your AC is over 8 years old or keeps failing, it may be time to upgrade. top air conditioners →
Sulaiman Sekh
Verified ExpertHVAC Expert & AC Repair Specialist
Sulaiman has 8+ years of hands-on experience in diagnosing and repairing air conditioning systems. He works with real AC units daily and ensures all guides are practical and based on real-world scenarios.
This article has been reviewed by an HVAC professional with real-world experience to ensure accuracy and practical usefulness. All recommendations are based on hands-on field work, not manufacturer spec sheets alone.