Split AC

Syed Zurnain Abbas

Troubleshooting Guide: Split AC Not Cooling but Fan Is Running

Split AC

When your split air conditioner’s fan is running but it isn’t cooling, it can be frustrating and uncomfortable, especially during hot weather. Understanding the possible causes and solutions can help you address the issue quickly and effectively. This article explores common reasons why your split ac not cooling but fan is running, along with steps you can take to troubleshoot and resolve the problem.

Common Reasons for Split AC Not Cooling

Insufficient Refrigerant

Refrigerant is the substance that your AC uses to cool the air. If there is a leak or the refrigerant levels are low, the unit may not be able to cool the air effectively. This is a common issue that requires professional attention to diagnose and fix.

Dirty Air Filters

Clogged or dirty air filters can restrict airflow, causing the AC to struggle with cooling. Regularly cleaning or replacing air filters is essential for maintaining optimal performance and efficiency.

Blocked Condenser Unit

The outdoor condenser unit plays a critical role in the cooling process. If it’s blocked by debris, leaves, or other obstructions, it can’t dissipate heat effectively, which impairs the cooling function. Ensuring the condenser is clear and clean can resolve this issue.

Faulty Thermostat

A malfunctioning thermostat can lead to incorrect temperature readings, causing the AC to fail in cooling properly. Checking the thermostat settings and ensuring it’s functioning correctly can help in diagnosing this problem.

Frozen Evaporator Coils

Evaporator coils can freeze due to issues like low refrigerant, poor airflow, or malfunctioning components. When the coils are frozen, the AC unit won’t be able to cool the air efficiently. This often requires turning off the unit to let the coils thaw and then addressing the underlying cause.

Electrical Issues

Problems with wiring or electrical components can prevent the AC from cooling. This includes issues like faulty capacitors, relays, or circuit boards, which can affect the cooling cycle despite the fan running.

Steps to Troubleshoot and Fix the Problem

Check and Clean Air Filters

Start by inspecting the air filters. If they are dirty or clogged, clean or replace them. This is one of the simplest yet most effective ways to ensure your AC unit operates efficiently.

Inspect the Thermostat

Ensure that the thermostat is set to the correct temperature and mode (cooling mode). Replace the batteries if needed and check for any signs of malfunction. A properly functioning thermostat is crucial for the AC’s cooling performance.

Clear the Condenser Unit

Go outside and inspect the condenser unit. Remove any debris, leaves, or obstructions that might be blocking airflow. Cleaning the condenser coils can also improve efficiency.

Thaw Frozen Evaporator Coils

If you suspect frozen evaporator coils, turn off the AC unit to allow the coils to thaw. This can take several hours. Once thawed, check for underlying issues such as low refrigerant levels or airflow restrictions that might be causing the coils to freeze.

Check Refrigerant Levels

Low refrigerant levels require professional attention. Contact an HVAC technician to check for leaks, refill the refrigerant, and ensure there are no other underlying issues.

Examine Electrical Components

If the above steps don’t resolve the issue, there might be an electrical problem. Faulty capacitors, relays, or wiring issues need to be diagnosed and fixed by a qualified technician. Avoid attempting electrical repairs yourself to prevent injury or further damage.

When to Call a Professional

Persistent Issues

If the AC continues to have cooling problems despite your troubleshooting efforts, it’s time to call a professional. Persistent issues might indicate more complex problems that require expert diagnosis and repair.

Refrigerant Leaks

Handling refrigerant requires specialized knowledge and equipment. If you suspect a refrigerant leak, it’s essential to have a licensed HVAC technician address the problem to ensure safe and effective repairs.

Electrical Repairs

Electrical components can be hazardous to work on without proper training. A professional technician can safely diagnose and fix electrical issues, ensuring your AC unit operates correctly and safely.


When your split AC is not cooling but the fan is running, it’s important to understand the potential causes and how to address them. By checking and maintaining key components such as air filters, the thermostat, and the condenser unit, you can often resolve common issues. However, for more complex problems like refrigerant leaks or electrical issues, professional assistance is necessary. Regular maintenance and timely repairs can keep your AC unit running efficiently, ensuring your home stays cool and comfortable.

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