What is Window AC and Diagram How Does it Works?

Window AC
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Window Air conditioners (ACs) efficiently cool smaller spaces and have become integral appliances for this purpose. These cost-effective and accessible compact units are popular for residential use, offering an effective solution to beat the heat.

In this article, we will elucidate the working principle of a window AC, exploring how it draws in hot air, cools it with a refrigerant-filled coil, and then circulates refreshing cool air back into the room.

Additionally, we will discuss the unit’s ability to reduce humidity levels, thereby providing a more comfortable indoor environment. Understanding the basics of how a window AC system operates can empower users to make informed decisions when selecting and maintaining these cooling devices.

What is a window? AC


A window air conditioner (AC) is a self-contained cooling system designed to be mounted in a window or a specially designed opening in a wall. It is a compact and individual cooling unit that is commonly used to cool single rooms or smaller spaces. Here are some key features and characteristics of a window AC

How Window AC Works learn with diagram

Window AC Diagram


A window air conditioner (AC) operates on the principles of refrigeration to cool and dehumidify the air in a room. Here’s a basic overview of how a window AC works:


  1. Refrigeration Cycle:
    • The heart of a window AC is the refrigeration cycle, which involves the circulation of refrigerant gas through a closed loop.
    • The refrigerant undergoes phase changes between gas and liquid to absorb and release heat.
  2. Components:
    • Compressor: The compressor is responsible for pressurizing the refrigerant gas. This compression increases the temperature of the gas.
    • Condenser Coil: The hot, pressurized refrigerant then flows to the condenser coil located on the outside part of the AC unit. Here, the refrigerant releases heat to the external environment and condenses into a high-pressure liquid.
    • Expansion Valve: The high-pressure liquid then passes through an expansion valve, which reduces its pressure. This causes the refrigerant to evaporate, absorbing heat in the process.
  3. Evaporator Coil:
    • The low-pressure, cool refrigerant now enters the evaporator coil inside the AC unit installed in the room.
    • Warm air from the room is drawn over the evaporator coil by a fan.
  4. Heat Exchange:
    • As the warm air passes over the cold evaporator coil, heat from the air is transferred to the refrigerant.
    • The now-warmed refrigerant vaporizes and returns to the compressor to start the cycle again.
  5. Dehumidification:
    • As the air cools, moisture in the air condenses on the cold evaporator coil and is collected in a drain pan or expelled outside.
  6. Fan:
    • The AC unit’s fan circulates the cooled and dehumidified air back into the room.
  7. Thermostat and Controls:
    • A thermostat monitors the room temperature and regulates the AC’s operation to maintain the desired temperature.
    • Controls on the unit or a remote allow users to adjust settings such as temperature, fan speed, and mode.

Advantages of Window AC

  1. Affordability:
    • Window AC units are generally more affordable than central air conditioning systems, making them a cost-effective cooling solution, especially for those on a budget.
  2. Ease of Installation:
    • Installing a window AC is relatively simple, and it doesn’t require extensive modifications to the existing structure. It can be mounted in a window or a specially designed opening in a wall.
  3. Energy Efficiency:
    • Compared to some portable air conditioners, window AC units can be more energy-efficient. They have a dedicated location for expelling heat to the outside, which can contribute to better cooling efficiency.
  4. Cooling Specific Areas:
    • Window AC units are designed to cool specific rooms or areas, allowing users to target cooling where it’s needed most. This can be more energy-efficient than cooling an entire home with a central AC system.
  5. Cooling Power:
    • Window AC units come in various cooling capacities measured in BTUs (British Thermal Units) per hour. Users can choose a unit with the appropriate BTU rating for the size of the room or space they want to cool.
  6. Space-Saving Design:
    • Window ACs are compact and do not take up floor space in the room. They are an ideal solution for smaller living spaces or rooms where floor space is limited.
  7. Customizable Settings:
    • Most window AC units come with adjustable settings, including temperature controls, fan speed, and mode options. Users have the flexibility to customize the cooling experience based on their preferences.
  8. Availability:
    • Various brands and models offer consumers a wide availability of window AC units. This range of options empowers consumers to select units that align with their specific cooling needs and preferences.

 Considerations for Choosing a Window AC

  1. Cooling Capacity (BTUs):
    • Determine the size of the room or space you intend to cool. The cooling capacity of a window AC is measured in British Thermal Units (BTUs) per hour. Choose a unit with the appropriate BTU rating based on the size of the room. Too few BTUs may result in inadequate cooling, while too many may lead to inefficient operation.
  2. Window Size and Compatibility:
    • Make sure the dimensions of the window or opening where you will install the AC unit, ensuring a secure fit and proper mounting. Verify that the chosen window AC unit is suitable for horizontal sliding windows, vertical sliding windows, or casement windows.
  3. Energy Efficiency Rating (EER):
    • Check the Energy Efficiency Ratio (EER) of the window AC. A higher EER indicates better energy efficiency. Energy-efficient models can save on electricity costs over time.
  4. Noise Level:
    • Consider the noise level of the unit, especially if it will be installed in a bedroom or other quiet areas. Look for window AC models with lower decibel (dB) ratings for quieter operation.
  1. Ease of Installation:
    • Choose a window AC unit that is easy to install, and make sure it comes with a complete installation kit. Some units may require additional support brackets, while others have a more straightforward installation process.
  2. User Controls and Features:
    • Look for units with user-friendly controls, including adjustable temperature settings, fan speeds, and mode options (cooling, fan-only, dehumidification). Some models come with remote controls for added convenience.
  3. Dehumidification Capability:
    • Consider the dehumidification capacity of the window AC. Units with effective dehumidification features can help control humidity levels in addition to cooling.
  4. Energy-Saving Features:
    • Look for energy-saving features such as programmable timers, sleep modes, and energy-efficient settings. These features can help reduce energy consumption and save on operating costs.
  5. Brand Reputation and Reviews:
    • Research and consider the reputation of the brand and read reviews from other users. Reliable brands often produce more durable and efficient window AC units.
  6. Warranty:
    • Check the warranty offered by the manufacturer. A longer warranty period can provide peace of mind and indicate the manufacturer’s confidence in the product.

Maintenance Tips

Proper maintenance is essential to ensure the efficient and reliable operation of a window air conditioner (AC). Here are some maintenance tips to keep your window AC in good condition:

  1. Regular Cleaning:
    • Clean or replace the air filter regularly. A dirty filter can restrict airflow, reducing the efficiency of the unit. Follow the manufacturer’s recommendations for cleaning or replacing the filter.
  2. Clean the Coils:
    • The evaporator and condenser coils can accumulate dirt over time. Clean these coils annually to maintain proper heat exchange. Use a soft brush or a vacuum cleaner to remove dust and debris.
  3. Check the Condensate Drain:
    • Ensure that the condensate drain is not clogged. A clogged drain can lead to water leakage and affect the unit’s performance. Clean the drain by passing a wire or using a vacuum to remove any blockages.
  4. Inspect the Seal:
    • Check the seal between the window AC unit and the window or wall opening. Make sure it is tight and secure to prevent warm air from entering and compromising cooling efficiency.
  5. Exterior Maintenance:
    • Clean the exterior of the unit, including the condenser coil, regularly. Remove any debris, leaves, or obstructions around the unit that could impede airflow.
  6. Check the Thermostat Accuracy:
    • Use a separate thermometer to check the accuracy of the thermostat. If there is a discrepancy, it may be necessary to recalibrate or replace the thermostat.
  1. Inspect the Fan:
    • Inspect the fan blades for any damage or obstruction. Clean the blades and the fan housing to ensure smooth operation.
  2. Inspect the Power Cord:
    • Check the power cord for any signs of damage, fraying, or wear. If you notice any issues, replace the cord to prevent electrical hazards.
  3. Test Controls and Settings:
    • Regularly test and calibrate the controls, including temperature settings, fan speeds, and modes. Ensure that all settings are functioning correctly.
  4. Inspect Insulation:
    • Check the insulation around the refrigerant lines. If there are signs of wear or damage, replace the insulation to maintain energy efficiency.
  5. Verify Window Seals:
    • Ensure that the window or wall seals around the unit are intact and in good condition. Replace or repair any damaged seals to prevent air leaks.
  6. Schedule Professional Maintenance:
    • Consider scheduling professional maintenance annually. A trained technician can perform a more thorough inspection, address potential issues, and recharge refrigerant if necessary.

Common Issues and Troubleshooting in Window AC

Window air conditioners can encounter common issues over time. Here are some common problems and troubleshooting tips:

  1. Unit Not Turning On:
    • Troubleshooting: Check the power source and ensure the unit is plugged in. Test the outlet with another device to confirm it’s functioning. If the outlet is working, inspect the power cord for any damage. Also, check the fuse or circuit breaker.
  2. Inadequate Cooling:
    • Troubleshooting: Verify that the unit is the correct size for the room. Clean or replace the air filter, as a dirty filter can restrict airflow. Ensure that the thermostat is set to the desired temperature. Clean the coils to maintain proper heat exchange.
  3. Unit Not Cooling Sufficiently:
    • Troubleshooting: Check for obstructions blocking the airflow around the condenser coil on the exterior of the unit. Clean the condenser coil and make sure the unit is not exposed to direct sunlight.
  4. Water Leakage Inside the Room:
    • Troubleshooting: Inspect the condensate drain for clogs. Clean the drain and ensure that it is draining properly. Check the unit’s tilt; it should be slightly tilted toward the outside to allow proper drainage.
  5. Unusual Noises:
    • Troubleshooting: Noises like rattling or squealing may indicate an issue with the fan or motor. Inspect the fan blades for damage or obstructions. Lubricate the motor if allowed by the manufacturer. If the issue persists, professional assistance may be required.
  6. Ice Formation on Coils:
    • Troubleshooting: Ice formation on the evaporator coils may be due to reduced airflow or refrigerant issues. Ensure the air filter is clean and not blocking airflow. Check for refrigerant leaks, and if ice persists, consult a professional technician.
  7. Continuous Cycling On and Off:
    • Troubleshooting: This could be due to a low refrigerant in system due to leak in somewhere In system fix the leak and refill the refrigerant. The dirty or blocked air filter, causing the unit to overheat. Clean or replace the filter and ensure proper airflow. If the problem persists, it may be a faulty thermostat or compressor, requiring professional attention.


In conclusion, window air conditioners are efficient and cost-effective cooling solutions for individual rooms or smaller spaces. Their ease of installation, affordability, and customizable features make them a popular choice for many households. To maximize the performance and lifespan of a window AC unit, regular maintenance is crucial. This includes cleaning or replacing air filters, inspecting coils, checking for proper drainage, and addressing any issues promptly.


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