Air Conditioner Won’t Cool Below 75? Discover 13 Reasons!

  • Got a problem with your air conditioner not cooling below 75 degrees running? It’s frustrating, especially when you’re craving that cool comfort on a scorching day. We’ve got the questions and information you need to tackle this head-on. Let’s dive into the common causes, troubleshooting tips, questions, and percent for reclaiming your chill zone.

    Depending on location and preference, the ideal air conditioner’s room temperature is about 68 – 75 degrees Fahrenheit (OF). /// Sometimes, however, the air conditioner won’t cool below 75, and you’ve to ask questions why.

    Your air conditioner won’t go below 75 OF because of the wrong sizing, higher outdoor temperature (above 95 OF), a dirty air filter, a tripped breaker, leaky ductwork, a blocked outdoor unit, faulty thermostat wiring, exhausted thermostat batteries, refrigerator leakage, questions, year, justanswer. 

    It could also be due to a clogged condensate line, iced-up evaporator coils, a defective compressor, or an older AC.

    Indeed, something must be wrong when your air conditioner won’t cool enough, significantly when it doesn’t drop below 75 degrees. 

    I’ll explain all those issues and their fixes to enable you to get your AC back cooling seamlessly.

    Let’s jump into it!

    air conditioner won't cool below 75

    In a rush? See the table below for quick fixes to the various issues that could prevent your air conditioner from cooling below 75 degrees. 

    My Air Conditioner Won’t Go Below 75 – Quick Troubleshooting Guide

     Likely Cause Quick Fix 
    1.Wrong AC Sizing Upgrade to the right AC size 
    2.Higher Outdoor Temperature (Above 95)Open the window and doors or use a cooling fan to supplement the AC
    3.Dirty Air Filter Replace the air filter if it’s dirty (do it after 1-2 months)
    4.Tripped Breaker Reset the breaker
    5.Leaky Ductworks Seal the leaky spots on the ductwork
    6.Blocked Outdoor Unit Remove any obstructions (debris, branches, shrubs, furniture, etcetera) around the condenser 
    7.Faulty Thermostat Wiring Have an HVAC pro check and fix the thermostat wiring 
    8.Exhausted Thermostat Batteries Replace the thermostat’s batteries 
    9.Refrigerant Leakage Contact an HVAC expert to fix the source of the refrigerant leakage and refill the refrigerant 
    10.Clogged Condensate Line Call an HVAC pro to unclog the condensate line if you can’t do it 
    11.Iced-Up Evaporator Coils Change the air filter but if that doesn’t work, call an HVAC expert 
    12.Faulty Compressor Contact an HVAC pro to check the compressor  
    13.Older Air Conditioner Replace the air conditioner if it’s older than 10-15 years

    Why Your Air Conditioner Won’t Cool Below 75 Degrees

    Your air conditioner won’t go below 75 degrees for different reasons. The most common ones are shared below:

    1. New Air Conditioner Won’t Cool Below 75 Because It’s the Wrong Size

    If your air conditioner is newly-installed or newly bought but cannot cool below 75 degrees, it’s likely the wrong size, mainly undersized. Such an AC won’t allow you to lower the thermostat temperature past a specific limit, in this case, below 75 degrees. 


    Matching your room size with the correct air conditioner capacity (or BTU rating) is essential. If the unit is undersized, it won’t cool your room, and if it’s oversized, it won’t be able to remove all the humidity, thus risking mold growth. 

    Below is an air conditioner sizing guide you can use on most window-mounted and portable home air conditioners:

    Maximum Cooled Area AC Capacity
    150 SQFT 5,000 BTU
    250 SQFT 6,000 BTU
    300 SQFT 7,000 BTU
    350 SQFT 8,000 BTU
    400 SQFT 9,000 BTU
    450 SQFT10,000 BTU
    550 SQFT12,000 BTU
    700 SQFT 14,000 BTU
    1,000 SQFT 18,000 BTU
    1,200 SQFT 21,000 BTU
    1,400 SQFT 23,000 BTU
    1,500 SQFT 24,000 BTU

    2. Extremely Higher Outdoor Temperature 

    While your air conditioner may cool just fine when the outdoor temperature is below 92 degrees, it won’t do it properly if it is above 75. Essentially, the air conditioner cools by 20 degrees below the outdoor temperature.

    So, if the outdoor temperature is 95 degrees, the AC will drop by 20 to 75 degrees, but if it’s 96 or higher, the cooling temperature will be above 75 degrees. 


    While there’s little to do since you don’t have power over the outdoor temperature, you can try lowering its effect indoors by shutting the windows and door. Additionally, you can use fans to supplement the AC. 

    my air conditioner won't go below 75

    3. Dirty Air Filter 

    Dirty air filters prevent the air conditioner from cooling correctly and may even cause it to turn off itself. That means the filter could be why your AC’s temperature won’t drop below 75 degrees.

    When the air filter is dirt clogged, it reduces the amount of cold air flow and thus reduces cooling. 


    Change the air filter if it’s dirty. Most manufacturers recommend replacing the AC filter after 1 – 2 months, depending on usage. 

    4. Tripping Breaker 

    Sometimes it’s harder for the air conditioner to cool well when the circuit breaker keeps tripping. The circuit breaker may trip off if it’s loose or faulty. So, you may have to examine the unit’s circuit breaker to see if it’s off. 


    Examine the circuit breaker to reset it if it’s tripped. However, if it continues tripping, contact a local electrician

    5. The Air Conditioner Will Not Cool Below 75 Due to Leaky Ductwork 

    If the ductwork leaks cold air, it may be hard for the air conditioner to run at a very low temperature. For that reason, it’s imperative to seal any air leakage sources to keep the AC’s temperature within a specific limit. 


    Inspect the ductwork for any leaky spots and seal them. If you cannot do it, talk to an HVAC expert. 

    6. Blocked Outdoor Unit 

    The outdoor unit, especially the condenser, should have proper airflow. Nothing should block it from good airflow, including debris, branches, furniture, and shrubs. 

    You’ve to look at all these things to ensure that none of them are blocking the condenser from adequate airflow and remove it. 


    Cut loose branches and shabby shrubs from blocking the condenser unit and clear any dirt or debris heaps around it. Remove anything else, including outdoor furniture, that could obstruct the AC. 

    7. Faulty Thermostat Wiring 

    If there’s a wiring fault on your AC’s thermostat, it’ll be hard to set it correctly. The faulty wiring causes the thermostat to fail, making it harder for the air conditioner to cool appropriately


    If you can, take out the thermostat and examine its wiring against the design in the manual. If something looks amiss, contact an HVAC expert. 

    new air conditioner won't cool below 75

    8. The Air Conditioner Thermostat Won’t Go Below 75 Due to Exhausted Batteries

    The thermostat depends on its batteries to run. If the batteries are power-drained or exhausted, the thermostat won’t be able to run correctly. So, keeping the temperature below 75 degrees or any other lower range will be challenging. 


    Replace the thermostat batteries and then try out the thermostat to see if its temperature setting is adjustable

    9. Refrigerant Leakage

    A drop in the refrigerant level affects the cooling performance of your air conditioner. A low refrigerant level means the AC cannot transfer warm heat from the inside to keep the indoor space cool. 

    Overall, issues like damage and wrong AC installation could cause the refrigerant to leak, and an expert can help you fix them. 


    A drop in the refrigerant level calls for a refill. Don’t, however, perform the refill as it requires an expert. So, contact an HVAC expert when you suspect a refrigerant leakage. Signs include an AC that won’t cool, wetness around the outdoor unit, and a smelly AC. 

    An HVAC export won’t just fix the source of the leakage but will also refill the refrigerant. 

    10. Clogged Condensate Line 

    Sometimes the condensate line accumulates too much dirt and debris, blocking it and deactivating the compressor. So, the compressor cannot run beyond a certain point, causing cooling loss


    Inspect the drain line for clogging and try unclogging it if you are handy and have the tools. But if you don’t, call an HVAC pro. 

    11. Iced-Up Evaporator Coils 

    Since the evaporator coils absorb the warm inside air before the refrigerant cools it (the air), it shouldn’t ice up. Some issues, however, such as a dirty air filter and refrigerant leakage, can cause the coils to ice up, thus making them unable to do their job. 


    Inspect the evaporator coils from icing over. If they are frozen, consider talking to an HVAC expert. Meanwhile, you can try to change the air filter. 

    12. Faulty Compressor 

    The source of the fault could be the compressor. If short-circuited, wrongly wired, or worn out, the compressor will restrict the air conditioner from cooling, as it won’t run well. Note that the compressor may also fail due to overheating or refrigerant leakage. 


    Since diagnosing a faulty compressor is difficult, it may be a good idea to contact an HVAC expert. 

    ac not cooling enough

    13. Older Air Conditioner 

    Lastly, the air conditioner might not be able to cool below 75 degrees because it’s too old. That might be the case if the AC is older than ten years. But overall, ACs have a 15-20-year lifespan


    Replace your air conditioner if you’ve been using it for more than 10 – 15 years. 

    People Also Ask 

    1. Why Is My AC Not Cooling Below 75 Degrees?

    Your AC might not be cooling below 75 degrees because it’s too old (older than ten years) or undersized. Other issues worth checking are a dirty air filter, frozen evaporator coils, clogged drain line, faulty thermostat, tripping breaker, and low refrigerant.

    2. Why Is My AC Not Cooling Below 77?

    Your AC won’t cool below 77 degrees if the air filter is dirt-clogged, the evaporator coil is iced-up, or the refrigerant level is low. Also, check for possible leaky ductwork, a faulty thermostat, tripped breaker, exhaust thermostat batteries, or the wrong AC size. 

    3. Why Is My AC Not Cooling Below 74?

    If your air conditioner won’t cool below 74 degrees, the issue could be that the AC is too small (undersized) or too old. It could also be that the air filter is dirty, the evaporator coils are frosted, or the condenser is obstructed. 

    Closing Thought When the Air Conditioner Won’t Cool Below 75:

    As shared, your air conditioner won’t cool below 75 degrees for different reasons. The unit itself could be the wrong size (applying to a new AC) or too old. 

    But still, issues like a dirty filter, leaky ductwork, tripped breaker, blocked drain, obstructed condenser, low refrigerant, iced-up evaporator coils, and a faulty thermostat could be the problem. So, consider all 13. 

    Also Read:

    Is it something simple like a clogged filter or could there be an underlying issue causing the discomfort? We’ll explore all these questions and more, ensuring that by the end of this post, you’ll have the knowledge to click those thermostat digits down to where they belong. Stay tuned for valuable insights that will help you beat the heat in no time.

    Common Cooling Challenges

    Refrigerant Leaks

    Refrigerant leaks can be a common culprit when an air conditioner won’t cool below 75. Low levels of refrigerant can significantly impact the cooling efficiency of your AC unit. Signs to watch out for include warm air blowing from the vents, hissing or bubbling sounds near the indoor unit, and ice buildup on the refrigerant line. It’s crucial to seek professional assistance to fix these leaks as handling refrigerants requires specialized knowledge and equipment.

    Professionals can accurately diagnose the extent of the leak and repair it effectively, ensuring that your system operates at its optimal level. Attempting a DIY fix for a refrigerant leak is not recommended due to safety concerns and potential damage to your AC unit.

    Outdoor Temperatures

    High outdoor temperatures play a significant role in determining how well your air conditioner performs. During extreme heatwaves, even properly functioning AC units might struggle to maintain lower temperatures indoors. It’s important for homeowners to adjust their expectations based on weather conditions; during scorching hot days, achieving indoor temperatures much lower than 75 degrees Fahrenheit may be unrealistic.

    For instance, if outdoor temperatures soar above 100 degrees Fahrenheit, it may be challenging for an AC unit to achieve a temperature setting significantly below 75 degrees indoors despite operating optimally. Therefore, understanding how outdoor conditions affect cooling efficiency helps manage expectations regarding indoor comfort during exceptionally hot weather.

    AC Unit Size

    The size of an AC unit has a direct impact on its ability to cool effectively. An undersized system will struggle to keep up with demand and maintain cooler temperatures indoors when faced with high heat loads. Proper sizing during installation is crucial; consulting an HVAC professional ensures that you invest in an appropriately sized system for your home’s specific cooling needs.

    Installing an oversized unit also poses problems as it cycles on and off too frequently without adequately dehumidifying the air or evenly distributing cool air throughout your home—a phenomenon known as short cycling—leading to discomfort and higher energy bills due to inefficiency.

    Airflow Issues

    Restricted airflow within an AC system can impede its cooling capabilities regardless of other factors such as refrigerant levels or outdoor temperature conditions. Common causes include dirty filters obstructing airflow or blocked vents hindering proper distribution of cooled air throughout your living space. Improving airflow involves regular maintenance tasks like changing filters every few months and keeping vents unobstructed by furniture or other items within your home.

    Thermostat Troubles

    Malfunctioning Devices

    Faulty thermostats or sensors can disrupt cooling. When the thermostat is not functioning properly, it may inaccurately read the temperature in the room, causing the air conditioner to not cool below 75 degrees. Identifying malfunctioning devices and their impact on temperature control is crucial. For example, a malfunctioning sensor might incorrectly detect that the room has reached the desired temperature when it actually hasn’t.

    Damaged thermostats can lead to erratic behavior from your air conditioning system. It’s essential to understand how these issues affect your unit’s ability to reach lower temperatures effectively. If you suspect a faulty thermostat or sensor is at play, consider seeking professional help for repair or replacement options for faulty components.

    One of the most common signs of a faulty thermostat is if your air conditioner runs constantly without reaching the set temperature. This could be an indicator that something within your thermostat isn’t working correctly and needs attention.

    Setting Adjustments

    Incorrect thermostat settings can prevent lower temperatures. Sometimes, homeowners inadvertently set their thermostats too high without realizing it. Optimal temperature settings are essential for efficient cooling; setting it too high will make it impossible for your air conditioner to cool below 75 degrees.

    It’s important to troubleshoot any potential issues with your thermostat and make adjustments as needed based on usage patterns and external conditions like humidity levels and outdoor temperatures. Ensuring that all settings are accurate will help optimize performance and ensure comfortable indoor temperatures during hot weather.

    Remember that even small adjustments in either direction can have a significant impact on energy consumption and comfort levels within your home.

    Component Failures

    Compressor Problems

    A malfunctioning compressor is a common cause of an air conditioner not cooling below 75 degrees. Signs of compressor issues include strange noises, warm air blowing from the vents, or frequent cycling on and off. When the compressor fails to function properly, it affects the system’s ability to regulate temperature effectively. As a result, your home may struggle to reach cooler temperatures even when the AC runs continuously.

    Seek professional help if you suspect compressor problems. A certified technician can diagnose the issue accurately and recommend appropriate repairs or replacements. Attempting DIY fixes for compressor issues is not recommended due to the complexity and safety risks involved.

    Evaporator Coils

    Dirty or frozen evaporator coils are another potential culprit behind an air conditioner failing to cool below 75 degrees. Over time, dust and debris can accumulate on the coils, hindering their ability to absorb heat from indoor air efficiently. If moisture builds up on the coils and freezes, it restricts airflow and diminishes cooling performance.

    Regular maintenance is crucial for ensuring optimal evaporator coil functionality. Homeowners should schedule annual professional maintenance services that include thorough cleaning of evaporator coils as part of routine upkeep for their HVAC systems. Alternatively, individuals can opt for DIY coil cleaning using specialized coil cleaners available in hardware stores.

    Airflow and Circulation

    Condenser Maintenance

    Neglected condenser units can contribute to poor cooling. When the condenser is not properly maintained, it can lead to reduced airflow and compromised heat transfer, making it difficult for the air conditioner to cool below 75 degrees. Regular maintenance and cleaning of the condenser unit are crucial in ensuring optimal performance. By removing debris such as leaves, dirt, and grass clippings from around the unit, you can prevent airflow obstructions that hinder efficient cooling.

    DIY tips for maintaining the condenser unit include gently hosing down the exterior to remove accumulated dust and grime. This simple step helps maintain proper airflow through the fins of the condenser coil, allowing heat to dissipate more effectively. By keeping the area surrounding the condenser clean and free from obstructions, you facilitate better air circulation, which is essential for achieving lower indoor temperatures.

    • Importance of regular maintenance

    • Cleaning debris around unit

    • Gently hosing down exterior

    Blocked Drain Lines

    Clogged drain lines can cause water backup within an air conditioning system, leading to increased moisture levels inside your home or building. The accumulation of moisture due to blocked drain lines can impede effective cooling by creating a damp environment that interferes with heat exchange processes. Recognizing signs such as water pooling around your indoor AC unit or unusual gurgling sounds coming from the drainage system indicates potential blockages that need attention.

    Clearing drain lines is vital in restoring proper AC function when dealing with an air conditioner that won’t cool below 75 degrees. Using a mixture of warm water and vinegar or a specialized cleaner helps dissolve mold or algae growth within clogged drain pipes. This process allows unrestricted flow of condensed water away from your HVAC system, preventing issues associated with excessive moisture buildup that negatively impacts cooling efficiency.

    AC Unit Sizing Concerns

    Undersized Units

    An undersized AC unit struggles to cool larger spaces. This happens because the unit’s capacity is insufficient for the area it needs to cool. For example, a small window unit may not effectively cool an entire floor of a house. The limited cooling capacity leads to the air conditioner running constantly without achieving the desired lower temperature.

    Understanding the limitations of undersized units is crucial. Homeowners need to consider their space’s square footage and insulation levels when choosing an air conditioning system. Upgrading to a properly sized AC system can significantly improve cooling efficiency and create a more comfortable indoor environment.

    Overworked Systems

    Overworking an AC system can prevent it from reaching lower temperatures, contributing to its inability to cool below 75 degrees Fahrenheit. Factors such as extreme outdoor temperatures, inadequate maintenance, clogged filters, or leaky ductwork can strain the system beyond its capabilities.

    Reducing strain on the AC unit involves taking proactive measures like regular filter replacements and professional maintenance checks. Ensuring proper insulation in attics and walls also helps maintain cooler indoor temperatures by reducing heat transfer from outside.

    Maintenance for Efficient Cooling

    Cleaning Coils

    Dirty coils can hinder cooling efficiency. Regular coil cleaning is crucial for optimal performance. Over time, the evaporator and condenser coils in your air conditioner can accumulate dust, dirt, and debris. This buildup insulates the coils, reducing their ability to absorb heat efficiently. As a result, the cooling capacity of your AC unit diminishes, leading to it struggling to cool below 75 degrees Fahrenheit.

    To maintain efficient cooling, you can use DIY methods such as gently vacuuming the coils or using a soft brush to remove debris. However, for more thorough cleaning and professional assistance, it’s advisable to schedule an annual maintenance service with an HVAC technician. They have specialized tools and expertise to clean the coils effectively without damaging delicate components.

    Professional maintenance not only ensures that the coils are cleaned properly but also allows technicians to inspect other vital parts of your air conditioning system for any potential issues that could affect its performance.

    Changing Filters

    Clogged air filters can impede airflow and cooling in your air conditioner. It’s important to replace these filters regularly as part of routine maintenance. When filters become clogged with dust and dirt particles, they restrict airflow into the system which reduces its ability to cool effectively.

    For efficient cooling performance and energy efficiency, it’s recommended by experts to replace disposable filters every 1-3 months depending on factors such as indoor air quality and pet hair shedding if applicable. Some high-efficiency filters may require less frequent replacement due to their superior filtering capabilities.

    Choosing the right type of filter is essential for maintaining optimal airflow while capturing airborne particles effectively. Pleated filters are popular choices as they strike a balance between capturing small particles without significantly restricting airflow like some high-efficiency models might do.

    Troubleshooting Tips

    Circuit Breakers

    Tripped circuit breakers can disrupt AC operation. If your air conditioner won’t cool below 75, start by checking the circuit breakers. Locate the electrical panel and look for any switches that are in the “off” position. Flip them back to “on” to reset the circuits.

    Addressing underlying electrical issues is crucial if breakers continue to trip frequently. This might involve consulting with a professional electrician to inspect and fix any wiring or voltage problems that could be causing the repeated tripping of circuit breakers.

    Internal Components

    Malfunctioning internal components can significantly impact an air conditioner’s cooling capabilities, preventing it from reaching temperatures below 75 degrees Fahrenheit. Check for faulty parts such as a malfunctioning compressor, evaporator coil issues, or a defective thermostat.

    Identifying these problematic internal components is essential in understanding why your AC isn’t cooling adequately. Once you’ve pinpointed the issue, consider repair options if feasible or replacement if necessary for restoring optimal cooling performance.

    When dealing with an air conditioner that won’t cool below 75 degrees Fahrenheit, it’s important to remember that there are several potential causes behind this issue.

    • Tripped circuit breakers may disrupt AC operation.

    • Malfunctioning internal components can affect cooling capabilities.

    • Checking and resetting circuit breakers is vital for troubleshooting.

    • Identifying faulty internal components helps understand temperature control issues.

    Professional Repair Services

    Seeking Expert Help

    When your air conditioner won’t cool below 75, and all the DIY troubleshooting has been exhausted, it’s time to seek professional help. HVAC technicians are equipped with the expertise and tools to accurately diagnose and repair complex AC issues. By hiring professionals, you can ensure that the underlying problem causing your AC to not cool below 75 is effectively addressed.

    Reputable HVAC technicians offer a range of services including thorough inspection, precise diagnosis, and efficient repairs. They have in-depth knowledge of various air conditioning systems, allowing them to identify specific issues that may be challenging for homeowners to pinpoint. They can provide valuable insights into maintaining optimal AC performance after resolving the cooling problem.

    Finding reputable professionals in your area is crucial when seeking expert help for your malfunctioning air conditioner. Look for certified technicians with positive customer reviews and a proven track record of delivering high-quality services. Referrals from friends or family members can also lead you to trustworthy professionals who excel in diagnosing and fixing AC issues promptly.

    Signs of Serious Issues

    Recognizing warning signs indicating more serious AC problems is essential in determining when professional intervention is necessary. If your air conditioner consistently fails to lower the temperature below 75 degrees despite regular maintenance efforts or if there are unusual sounds or odors coming from the unit, these could be indicators of significant underlying issues requiring professional attention.

    Ignoring persistent cooling problems can lead to further damage within your air conditioning system. It’s crucial to know when it’s time to call a professional immediately rather than attempting additional DIY fixes that might exacerbate the issue at hand.

    Preventing further damage by addressing serious issues promptly through professional intervention can save you from costly repairs down the line while ensuring that your home remains comfortable during hot weather conditions.


    You’ve learned about the common issues that can prevent your air conditioner from cooling below 75 degrees. From thermostat malfunctions to inadequate airflow, each component plays a crucial role in your AC’s performance. Remember, regular maintenance and prompt professional repairs are key to ensuring your unit operates efficiently. Don’t let these cooling challenges leave you sweating! Take action and address these issues to enjoy a comfortably cool home environment.

    Now that you’re equipped with troubleshooting tips and insights into potential problems, don’t hesitate to reach out to HVAC professionals if needed. Keep your cool and stay proactive in maintaining your air conditioner for optimal performance.

    Frequently Asked Questions

    Why is my air conditioner not cooling below 75 degrees on hot days outside?

    If your air conditioner won’t cool below 75, it could be due to thermostat issues, inadequate maintenance, or component failures. Check and replace the air filters regularly, ensure proper airflow around the unit, and consider professional inspection to address any underlying problems.

    How can I improve the efficiency of my air conditioning unit on hot days?

    To enhance your AC’s efficiency, keep blinds closed during peak sun hours, seal any leaks in ductwork or windows, and schedule regular maintenance such as cleaning coils and checking refrigerant levels. These simple steps can optimize performance and lower energy bills.

    Is it normal for an air conditioner to struggle with cooling in extreme heat outside?

    In sweltering conditions, your AC may have difficulty maintaining lower temperatures. This strain on the system is similar to expecting a car to perform optimally under extreme stress – it’s tough! Consider using fans or implementing other cooling strategies during exceptionally hot spells.

    Can a wrongly-sized AC unit affect its ability to cool effectively?

    Absolutely! An undersized unit will struggle to cool adequately while an oversized one may short cycle frequently. It’s like trying to fit into shoes that are either too small or too big – neither scenario leads to comfort or optimal performance. Ensure proper sizing for efficient cooling.

    When should I consider professional repair services for my struggling air conditioner questions?

    If basic troubleshooting doesn’t resolve the issue or if you notice strange sounds/smells from your AC unit, it’s time for professional intervention. Just like seeking medical advice when home remedies don’t work – skilled technicians can diagnose and treat complex HVAC ailments effe