LS Aircon Servicing Singapore

Aircon is Blowing Hot Air

Top 8 Reasons Why Your Aircon is Blowing Hot Air

Nothing is more irritating than an aircon blowing hot air in the hot blazing summer. A sudden gust of warm air from your aircon when you’re expecting cool relief can be frustrating and uncomfortable. Several factors can contribute to this issue, ranging from minor problems to more complex malfunctions. Let’s explore in detail the top eight reasons why your aircon might be blowing hot air.

Why is My Aircon Blowing Hot Air?

This section elaborates on the most common causes of aircon blowing hot air. 

Thermostat Settings

The thermostat is the control center of your aircon system, dictating when the unit turns on or off and at what temperature. Incorrect thermostat settings are a common reason for an aircon blowing warm air.

Ensure your thermostat is set to “Cool” mode and that the temperature setting is lower than the current room temperature. Sometimes, the thermostat may be inadvertently set to “Heat” mode, causing the aircon to blow hot air. Additionally, check the batteries in your thermostat, as low battery power can affect its functionality.

Dirty Air Filters

Clogged or dirty air filters can significantly impact your aircon’s performance. Air filters trap dust, dirt, pollen, and other airborne particles, preventing them from entering your home and the aircon system. However, when filters become congested, airflow is restricted, leading to reduced cooling efficiency and resulting in air conditioners blowing hot air.

To maintain optimal airflow, it is essential to replace or clean your air filters regularly every 1-3 months, depending on usage and the filter type. This simple maintenance task improves air quality and helps your air conditioner operate more effectively.

Refrigerant Leaks

Refrigerant is the substance responsible for absorbing heat from indoor air and releasing it outside, cooling your home in the process. If there’s a refrigerant leak in your aircon system, it can lead to hot air blowing from the vents.

Signs of a refrigerant leak include:

  • Reduced cooling capacity
  • Hissing sounds near the AC unit
  • Ice buildup on the refrigerant lines
  • Increased energy bills due to decreased efficiency

A licensed HVAC technician like Aircon Servicing Singapore should address refrigerant leaks promptly. They will locate and repair the leak, recharge the system with the correct amount of refrigerant, and ensure your aircon is functioning optimally.

Why my Aircon is Blowing Hot Air

Compressor Issues

The compressor is a vital component of your aircon system. It compresses the refrigerant and facilitates heat transfer. If the compressor malfunctions or fails, your aircon won’t be able to cool the air properly, leading to hot air output.

Common compressor issues include:

  • Electrical failures
  • Mechanical damage
  • Motor problems

A malfunctioning compressor requires professional diagnosis and repair. HVAC technicians have the expertise and tools to assess compressor issues accurately and restore your AC’s cooling performance.

Electrical Problems

Electrical problems can disrupt the functioning of your aircon, resulting in the aircon blowing hot air or failing altogether. Issues such as faulty wiring, capacitor problems, or a tripped circuit breaker can affect the aircon’s ability to cool effectively.

Signs of electrical issues with your AC include:

It’s crucial to have a qualified electrician or HVAC technician inspect and address any electrical problems promptly to prevent further damage to your aircon system.

Blocked Condenser Unit

The condenser unit, located outside your home, plays a vital role in releasing heat from the refrigerant. If the condenser is obstructed by debris, vegetation, or other objects, it can’t expel heat efficiently, resulting in reduced cooling performance and hot air blowing from your aircon.

Regularly clean the area around your condenser unit to ensure adequate clearance for optimal airflow. Trim vegetation and remove debris to prevent airflow restrictions and maintain your aircon’s cooling efficiency.

Insufficient Insulation

Poor insulation in your home can contribute to hot air issues with your aircon. Inadequate insulation allows cool air to escape and warm air to enter, making it challenging for your AC to maintain desired temperatures.

Areas to check for insulation improvement include:

  • Walls
  • Windows
  • Doors
  • Attic

Improving insulation in these key areas enhances energy efficiency and helps your aircon cool your home more effectively. Consider consulting with an insulation specialist to assess and upgrade your home’s insulation as needed.

Aircon is Blowing Hot Air Singapore

System Age and Maintenance

The age and maintenance of your aircon system also play a significant role in its performance. Over time, aircon can experience wear and tear, leading to decreased efficiency and potential hot air problems.

Regular maintenance, including:

  • Cleaning
  • Lubricating moving parts
  • Inspecting components

If your AC unit is old and inefficient, upgrading to a newer, more energy-efficient model may be beneficial. Newer systems often feature advanced technology, improved energy efficiency ratings, and enhanced cooling capabilities, providing better comfort and long-term cost savings.


In conclusion, several factors can be responsible for an aircon blowing hot air, ranging from simple issues like thermostat settings and dirty filters to more complex problems like refrigerant leaks or compressor malfunctions. Regular maintenance, prompt repairs, and professional inspections are key to ensuring your aircon operates efficiently and delivers cool, comfortable air when you need it most. By addressing these potential issues proactively, you can enjoy reliable and effective cooling throughout the summer months.

Frequently Asked Questions

The fan located in the indoor unit draws warm air from inside the house via the return air ducts. This air is compressed and spread inside the room.
The initial step, which may seem more proactive, is to turn off your aircon unit. Running the unit while a component is loose or if the condenser isn't functioning correctly can potentially lead to further damage.
An AC unit can also be configured to heat up and warm your home or office during colder months.