Why Your AC Isn’t Cooling Below 75: Common Causes and Solutions

By SmartHomeBit Staff •  Updated: 09/04/23 •  26 min read
How-To

When your AC is not cooling below 75 degrees, it can be frustrating and uncomfortable, especially during hot summer months. Understanding the possible causes of this issue is crucial in finding a solution. Several factors can contribute to an AC not cooling below 75 degrees, and it’s important to identify them to address the problem effectively.

Possible reasons for an AC not cooling below 75 degrees include:

  1. Incorrect Thermostat Settings: Check if the thermostat is set to the desired temperature and in cooling mode.
  2. Dirty or Clogged Air Filters: Dirty air filters can restrict airflow and hinder the cooling process.
  3. Insufficient Refrigerant Level: Low refrigerant levels can affect cooling performance and may indicate a leak.
  4. Faulty Compressor: A malfunctioning compressor can lead to inadequate cooling or no cooling at all.
  5. Condenser Coils Covered in Dirt or Debris: Accumulated dirt on the condenser coils can hinder heat transfer and reduce cooling efficiency.
  6. Damaged Ductwork: Leaks or cracks in the ductwork can result in cooled air escaping before reaching the desired areas.

To troubleshoot an AC not cooling below 75 degrees, take these steps:

  1. Check Thermostat Settings: Ensure the thermostat is set to the desired temperature and cooling mode.
  2. Clean or Replace Air Filters: Clean or replace the air filters regularly to maintain proper airflow.
  3. Inspect and Recharge Refrigerant Level: If low refrigerant is suspected, consult a professional to inspect and recharge the system if necessary.
  4. Have the Compressor Checked by a Professional: If the compressor is suspected to be faulty, contact an HVAC professional for diagnosis and repair.
  5. Clean the Condenser Coils: Regularly clean the condenser coils to remove dirt and debris and improve cooling efficiency.
  6. Inspect and Repair Damaged Ductwork: If there are signs of damage in the ductwork, have a professional inspect and repair it.

While troubleshooting can be helpful, there are instances when professional help is necessary. Seek professional assistance if the problem persists, or if you are uncertain about performing any repairs or inspections yourself.

To maintain an efficient air conditioning system, remember to clean or replace air filters regularly, schedule professional maintenance at least once a year, and keep the area around the outdoor unit clean and free from obstructions.

By understanding the possible causes, troubleshooting methods, and when to seek professional help, you can address the issue of an AC

What Could Cause an AC Not Cooling Below 75?

If your AC is not cooling below 75 degrees, several factors may be causing the issue. Consider the following possibilities:

  1. Improper Thermostat Settings: Check the thermostat settings to ensure it is set to a temperature below 75 degrees. Make sure it is set to “cool” mode and the fan is on “auto.”
  2. Clogged Air Filters: Dirty or clogged air filters restrict airflow, reducing the cooling efficiency of your AC. Check and replace the air filters if they are dirty.
  3. Thermostat Location: The thermostat’s location can affect its accuracy. If it is placed near a heat source or in direct sunlight, it may not accurately measure the room temperature, leading to improper cooling.
  4. Insufficient Refrigerant: Low refrigerant levels can prevent your AC from cooling effectively. If you suspect this is the issue, contact a professional HVAC technician to check and recharge the refrigerant.
  5. Blocked Condenser Unit: The condenser unit located outside your home needs proper airflow to function efficiently. Check for any debris, vegetation, or obstructions around the unit that may be blocking airflow.
  6. Faulty Compressor: The compressor is responsible for cooling the air. If it is malfunctioning or damaged, it may not be able to cool the air below 75 degrees. A professional technician will need to diagnose and repair or replace the compressor.
  7. Leaking Ductwork: Leaks in your ductwork can lead to air loss, reducing the cooling capacity of your AC system. Inspect the ductwork for any visible leaks and have them sealed by a professional.
  8. Improper Insulation: Insufficient insulation in your home can result in heat gain, making it difficult for your AC to cool the space below 75 degrees. Consider improving insulation in your home to enhance cooling efficiency.
  9. Undersized AC Unit: If your AC unit is too small for the space it is trying to cool, it may struggle to reach temperatures below 75 degrees on hot days. In this case, you may need to upgrade to a larger capacity AC unit.
  10. Other Mechanical Issues: There may be other mechanical issues, such as a faulty fan motor or a malfunctioning control board, that are preventing your AC from cooling properly. It is best to consult with a professional HVAC technician to diagnose and resolve these issues.

Identifying the underlying cause of your AC not cooling below 75 degrees can be complex. If basic troubleshooting steps do not resolve the issue, it is recommended to seek assistance from a qualified HVAC technician.

Possible Reasons for an AC Not Cooling Below 75

Struggling with your AC not cooling below 75? Let’s dive into the possible reasons behind this issue. From incorrect thermostat settings to dirty air filters, insufficient refrigerant level to a faulty compressor, condenser coils covered in dirt or debris to damaged ductwork—we’ll explore all the potential culprits causing your AC’s inefficiency. Get ready to uncover the reasons behind your AC’s lackluster cooling performance and learn how to address them once and for all.

1. Incorrect Thermostat Settings

When facing an AC that is not cooling below 75 degrees, it is crucial to take into account the possibility of incorrect thermostat settings. Here are some factors to consider:

By addressing these potential issues related to incorrect thermostat settings, you can effectively troubleshoot the AC not cooling below 75 degrees and determine if further action is necessary.

2. Dirty or Clogged Air Filters

Dirty or clogged air filters are a common cause of an AC not cooling below 75. Here are some important details to consider:

  1. Dirty air filters restrict airflow and reduce the efficiency of the air conditioning system. They can accumulate dust, dirt, and other airborne particles over time.
  2. Clogged air filters, such as dirty or clogged air filters, can lead to reduced cooling capacity as the restricted airflow prevents the proper circulation of cool air throughout the space.
  3. Regularly cleaning or replacing air filters, specifically dirty or clogged air filters, is crucial for maintaining optimal air quality and the cooling performance of the AC system.
  4. Experts recommend cleaning or replacing air filters, including dirty or clogged air filters, every 1-3 months, depending on the manufacturer’s instructions and the level of dust or allergens in the environment.
  5. When cleaning air filters, use a vacuum cleaner or gently wash them with water and mild soap. Allow them to dry completely before reinstalling.
  6. If the air filters, especially dirty or clogged air filters, are severely clogged or damaged, it is best to replace them with new ones to ensure optimal airflow and cooling efficiency.

Regular maintenance of air filters, such as dirty or clogged air filters, not only helps in maintaining a cooler environment but also extends the lifespan of the AC system and improves overall indoor air quality.

3. Insufficient Refrigerant Level

One possible reason for an AC not cooling below 75 is an insufficient refrigerant level, which can be attributed to a leak or inadequate initial refrigerant charge. Over time, refrigerant can escape from the system due to leaks in the refrigerant lines, connections, or components. Therefore, it is crucial to have a professional HVAC technician locate and repair any leaks. Additionally, if the AC system was not properly charged with refrigerant during installation or maintenance, there may not be enough refrigerant to effectively cool the air. In such cases, a professional technician can measure the refrigerant levels and recharge the system if necessary.

Addressing an insufficient refrigerant level is essential because refrigerant is responsible for absorbing heat from the indoor air and transferring it outside. Without enough refrigerant, the AC system cannot effectively cool the air. Therefore, it is crucial to have a professional HVAC technician diagnose and resolve any issues with the refrigerant level to ensure optimal cooling performance.

4. Faulty Compressor

When an AC is not cooling below 75, one possible reason could be a faulty compressor. Here are some factors to consider:

If you suspect that a faulty compressor is the cause of your AC not cooling below 75, it is best to seek professional help to ensure an accurate diagnosis and appropriate solution.

5. Condenser Coils Covered in Dirt or Debris

When an AC is not cooling below 75 degrees, one possible reason could be that the condenser coils are covered in dirt or debris. Follow these steps to address this issue:

  1. Turn off the AC unit and unplug it from the power source for safety.
  2. Locate the outdoor unit that houses the condenser coils.
  3. Inspect the coils visually to see if they are covered in dirt or debris.
  4. If you see dirt or debris, use a soft brush or a vacuum cleaner with a brush attachment to gently remove the buildup.
  5. Be careful not to damage the delicate fins of the coils while cleaning.
  6. If the dirt or debris is stubborn, you can also use a coil cleaner recommended by the AC manufacturer.
  7. After cleaning, rinse the coils with water to remove any remaining residue.
  8. Allow the coils to dry completely before turning the AC unit back on.
  9. Regularly check and clean the condenser coils to prevent future buildup of dirt or debris.

By properly maintaining the condenser coils, you can help ensure that your AC system functions efficiently and cools below 75 degrees.

6. Damaged Ductwork

Damaged ductwork can have a significant impact on the cooling efficiency of your air conditioning system. When dealing with damaged ductwork, there are several key factors to consider:

  1. Leaky ducts: Holes or leaks in the ductwork can cause cool air to escape before reaching the intended areas of your home or office. This can result in decreased cooling performance and higher energy consumption.
  2. Blocked airflow: Damaged ducts can become blocked by debris, dust, or even pests. Any blockage in the ductwork restricts the airflow, making it more difficult for your AC to effectively cool your space.
  3. Poor insulation: Damaged ductwork often means compromised insulation. Insufficient insulation can cause the air to lose its coolness while traveling through the ducts, leading to reduced cooling efficiency.
  4. Inconsistent temperature distribution: When ductwork is damaged, it can result in uneven distribution of temperatures throughout your space. Some rooms may become too hot while others remain cool, creating an uncomfortable environment.
  5. Increased energy costs: Damaged ductwork forces your air conditioning system to work harder, resulting in higher energy consumption and increased utility bills.
  6. Reduced indoor air quality: Damaged ductwork can allow contaminants such as dust, pollen, and other allergens to enter your indoor air. This can have a negative impact on air quality and potentially lead to respiratory issues.

Addressing damaged ductwork is crucial to ensure optimal cooling performance and energy efficiency. It is recommended to consult a professional HVAC technician to inspect and repair any issues with your ductwork.

How to Troubleshoot an AC Not Cooling Below 75

Are you struggling with an AC that just won’t cool below 75 degrees? Don’t fret! In this troubleshooting guide, we’ll walk you through some effective tips and tricks to get your AC back on track. First, we’ll dive into checking your thermostat settings, ensuring they’re optimized for cooler temperatures. Next, we’ll tackle the importance of clean or replaced air filters for improved airflow. We’ll also explore ways to inspect and recharge refrigerant levels, as well as when it’s time to call in a professional for compressor checks. We’ll touch on the significance of cleaning condenser coils and the necessity of inspecting and repairing any damaged ductwork. Say goodbye to the heat and embrace a refreshingly cool home once again!

Check Thermostat Settings

2. Clean or Replace Air Filters

When dealing with an AC that is not cooling below 75 degrees, one of the potential reasons could be dirty or clogged air filters. It is crucial to regularly clean or replace the air filters to ensure proper airflow and efficient cooling.

  1. Turn off the AC unit and locate the air filter compartment.
  2. Clean or replace the air filters by removing the air filter from the compartment.
  3. Inspect the filter for any visible dirt, debris, or dust accumulation.
  4. If the filter is washable, rinse it with water until all dirt is removed. Allow it to dry completely before reinserting it into the compartment.
  5. For disposable filters, replace them with new ones that are compatible with your AC unit. Make sure to follow the manufacturer’s instructions for proper installation.
  6. Before reinstalling the filter, clean the area inside the compartment by using a soft brush or vacuum to remove any remaining debris.
  7. Place the cleaned or new filter back into the compartment, ensuring it fits securely.
  8. Close the air filter compartment and turn on the AC unit.
  9. Monitor the temperature to see if the AC is now able to cool below 75 degrees.

By regularly cleaning or replacing air filters, you can improve the airflow in your AC system and prevent blockages that can cause insufficient cooling. Proper maintenance of air filters is essential for the overall performance and energy efficiency of your air conditioning unit.

3. Inspect and Recharge Refrigerant Level

  1. To inspect and recharge the refrigerant level in your AC unit, follow these steps:
  2. Turn off the AC unit and unplug it from the power source for safety.
  3. Locate the refrigerant lines. These are typically copper pipes located near the condenser unit outside your home and the evaporator coil inside your home.
  4. Inspect the refrigerant lines for any signs of leaks or damage. Look for oil stains, bubbles, or hissing sounds, which may indicate a leak.
  5. If there are no visible leaks, carefully remove the service valve caps from the refrigerant lines.
  6. Attach a refrigerant gauge to the service valve. This will allow you to measure the refrigerant pressure.
  7. Compare the pressure reading on the gauge to the recommended pressure range for your AC unit. If the pressure is too low, the refrigerant level needs to be recharged.
  8. If the refrigerant level needs to be recharged, carefully attach a canister of the appropriate refrigerant to the service valve. Follow the manufacturer’s instructions for proper handling and charging.
  9. Slowly open the valve on the canister to release the refrigerant into the AC system. Monitor the pressure gauge to ensure the correct amount of refrigerant is added.
  10. Once the desired pressure is reached, close the valve on the canister and remove it from the service valve.
  11. Replace the service valve caps and ensure they are tightly secured.
  12. Turn on the AC unit and monitor its performance. If the air is now cooling below 75, the refrigerant level has been successfully recharged.

Inspecting and recharging the refrigerant level should only be done by a professional if you are not confident in performing these steps yourself. Mishandling refrigerant can be dangerous and may require specialized equipment.

4. Have the Compressor Checked by a Professional

If your AC is not cooling below 75, it is imperative to have the compressor checked by a professional. Here are the steps to follow:

  1. Contact an HVAC technician to schedule an inspection of the compressor to have it checked by a professional.
  2. The professional technician will visually inspect the compressor for any visible signs of damage or malfunction.
  3. They will also ensure the electrical connections are secure and functioning properly by conducting tests.
  4. Using specialized tools, the technician will measure the refrigerant levels in the system. If the levels are low, it may indicate a leak or another issue that requires attention.
  5. If the compressor is found to be faulty, the technician will recommend either repairing or replacing it, depending on the extent of the damage.
  6. Additionally, the technician will investigate other potential causes of the AC not cooling below 75, such as dirty coils or blocked airflow.
  7. Based on their findings, the professional will provide you with a detailed report and suggest the necessary repairs or maintenance required to restore proper cooling.

Having the compressor checked by a professional is crucial for accurate diagnosis of the problem and to prevent further damage to your AC system. Regular maintenance and inspections can promote optimal performance and prolong the lifespan of your air conditioner.

5. Clean the Condenser Coils

To clean the condenser coils of your AC unit, follow these steps:

  1. Turn off the power: Before starting any maintenance, make sure to turn off the power to your AC unit.
  2. Access the coils: Locate the condenser unit, which is usually located outside of your home. Remove any debris or obstructions around the unit.
  3. Gently clean the coils: Use a soft brush or vacuum to remove any dirt, dust, or debris from the coils. Be careful not to damage the delicate fins of the coils.
  4. Rinse with water: Once the loose debris is removed, use a hose to gently rinse the coils with water. Make sure to direct the water from top to bottom to effectively clean the coils.
  5. Clean the Condenser Coils: If there are any stubborn stains or dirt on the coils, you can use a mild detergent mixed with water. Apply the mixture to the coils and scrub gently with a brush. Rinse thoroughly with water afterwards.
  6. Allow to dry: After cleaning, let the coils air dry completely before turning the power back on and using your AC unit.
  7. Maintain regular cleaning: To prevent future build-up and maintain proper functioning, it is recommended to clean the condenser coils at least once a year.

By regularly cleaning the condenser coils of your AC unit, you can ensure optimal cooling efficiency and extend the lifespan of the unit. Keep in mind that if you are not comfortable or confident in performing this maintenance task, it is best to seek professional help.

6. Inspect and Repair Damaged Ductwork

  1. When inspecting and repairing damaged ductwork in your air conditioning system, carefully follow these steps:
  2. Visually inspect the ductwork for any noticeable signs of damage, such as holes, leaks, or disconnected sections.
  3. Utilize a flashlight to get a closer look inside the ductwork and ensure there are no hidden damages or obstructions.
  4. If any holes or leaks are detected, seal them using aluminum foil tape or mastic sealant.
  5. Reconnect any disconnected sections of the ductwork securely using metal screws or clamps.
  6. Thoroughly clean the ductwork by using a vacuum cleaner or brush to eliminate any dirt, dust, or debris that may have accumulated.
  7. Inspect the insulation around the ductwork and promptly repair or replace it if there are any signs of damage or deterioration.
  8. Once the repairs are completed, test the system to ensure optimal airflow and efficiency.

By inspecting and repairing damaged ductwork, you can significantly improve the airflow and overall performance of your air conditioning system, enabling it to cool your space effectively.

When to Seek Professional Help for an AC Not Cooling Below 75

If your AC is not cooling below 75 degrees Fahrenheit, there are certain situations where it is advisable to seek professional help:

  1. Prolonged Issue: If the AC has consistently failed to cool below 75 degrees for an extended period, despite attempting troubleshooting steps, it is time to consult a professional. This indicates a persistent problem that requires expert attention.
  2. Unusual Noises or Smells: If the AC is emitting strange noises, such as grinding, rattling, or banging sounds, or if there are unusual odors coming from the unit, it is best to have a professional inspect it. These signs could indicate mechanical issues or potential hazards.
  3. Inadequate Airflow: If the AC is blowing weak or inconsistent airflow, it could be a sign of a blocked or damaged air duct, a malfunctioning blower fan, or other underlying issues. A professional can diagnose and resolve the problem effectively.
  4. Refrigerant Leaks: If you suspect a refrigerant leak, such as when the AC is not cooling sufficiently and frost or ice is forming on the evaporator coils, it is crucial to consult a professional. Handling refrigerant requires specialized knowledge and equipment.
  5. Electrical Problems: If you experience frequent tripping of circuit breakers, notice sparks or exposed wires, or encounter any electrical issues related to the AC, it is essential to seek professional help. Electrical problems can be hazardous and require the expertise of a trained technician.
  6. Old or Faulty System: If your AC system is old or has a history of recurring issues, it may be more cost-effective to consult a professional rather than attempting DIY repairs. A professional can assess the overall condition and performance of the system and recommend the best course of action.
  7. Warranty Coverage: If your AC is still under warranty, attempting DIY repairs or modifications may void the warranty. It is advisable to consult the manufacturer or a professional authorized by the manufacturer to ensure warranty coverage remains intact.

Remember, an AC system can be complex, and attempting repairs without proper knowledge and experience can lead to further damage or safety risks. Seeking professional help in the above situations ensures that the problem is properly diagnosed and resolved, restoring optimal cooling performance to your AC system.

Tips for Maintaining an Efficient Air Conditioning System

To ensure that your air conditioning system cools effectively, consider these tips for maintaining an efficient AC system:

  1. Clean or replace air filters regularly: Dirty or clogged air filters restrict airflow and reduce cooling efficiency. Clean or replace filters every 1-3 months, or as recommended by the manufacturer.
  2. Keep the outdoor unit clean: Clear any debris, leaves, or dirt from the outdoor unit regularly. This allows for proper airflow and prevents the system from working harder than necessary.
  3. Check and clean the evaporator coils: Over time, the evaporator coils can accumulate dirt and dust, inhibiting heat transfer. Schedule regular cleaning or maintenance to keep the coils clean and maximize cooling efficiency.
  4. Ensure proper insulation: Properly insulate your home to prevent cool air from escaping and warm air from entering. Insulation helps the AC system cool effectively and reduces energy waste.
  5. Seal air leaks: Inspect windows, doors, and other potential areas for air leaks. Seal any gaps or cracks to prevent warm air from entering and cool air from escaping.
  6. Use ceiling fans: Utilize ceiling fans to enhance air circulation and create a cooling breeze. This allows you to set the thermostat at a slightly higher temperature while maintaining comfort.
  7. Programmable thermostat: Install a programmable thermostat to regulate the temperature and optimize energy usage. Set the thermostat to higher temperatures when you’re away or asleep to reduce cooling costs.
  8. Regular maintenance: Schedule professional maintenance for your AC system at least once a year. This includes inspections, cleaning, and tuning to ensure optimal performance and identify any potential issues.
  9. Avoid heat-generating activities: Minimize activities that generate heat during the hottest parts of the day. This includes using heat-generating appliances or running the oven, as they can increase the workload on your AC system.
  10. Consider shade options: Provide shade to your home by using curtains, blinds, or external shading devices. This helps reduce heat gain from direct sunlight and eases the cooling load on your AC system.

By following these tips, you can maintain an efficient air conditioning system that cools effectively and keeps your indoor environment comfortable during hot weather.

Frequently Asked Questions

Why is my AC not cooling below 75 degrees even though it’s running?

There could be several reasons for this issue. It’s important to consider external factors such as the temperature outside and give the system enough time to cool the house down. Additionally, a dirty/clogged air filter, weak or dead thermostat batteries, a tripped circuit breaker, or an obstructed condenser can all contribute to insufficient cooling. Checking and replacing the air filter, replacing thermostat batteries, checking the electrical panel, and inspecting the condenser for any obstacles are recommended troubleshooting steps.

Can a dirty air filter affect the cooling performance of my AC?

Yes, a dirty air filter can impede airflow and cause your AC to work inefficiently. Neglecting to change the air filter can even lead to damage to the blower motor. To prevent this, it is important to regularly check and replace air filters as necessary.

How do I check if the thermostat batteries are weak or dead?

If your thermostat is battery-powered, you can check the batteries by replacing them with new ones. Monitor the room temperatures to see if there is any improvement in AC performance. If the problem persists, you may need to test the thermostat using a thermometer or consult a professional for assistance.

What should I do if my AC is not working after a tripped circuit breaker?

First, check the electrical panel to identify the breaker that covers the air conditioner. If the breaker appears fine but the AC is still not working, try manually checking if the breaker is fully engaged. If you are unable to resolve the issue, it is recommended to hire a professional to inspect and repair the AC system.

How can a blockage or obstruction at the condenser affect AC cooling?

If there is a blockage or obstruction at the condenser, it can hinder the airflow, which in turn affects the cooling performance of your AC. It is important to inspect the condenser regularly and remove any debris or unwanted elements that might be obstructing the airflow.

What are some common reasons why an AC might not cool to the desired temperature?

Some common reasons include an underpowered AC that is too small for the space, leaky pipes leading to refrigerant dripping, an older air conditioner that may require maintenance or replacement parts, and an inadequately cleaned or suffocating condenser. It is recommended to have regular maintenance, proper installation, and ventilation to ensure your AC performs optimally.

SmartHomeBit Staff