Why My Air Conditioner Not Cooling Below 75 – How to Fix It


If your air conditioning temperature is below 75 ℃, you will feel very uncomfortable. You know you want to set the temperature at 75 degrees, but the thermostat tells you that the temperature in your home is much higher than this temperature. Even if your system has been running for several hours. With the high temperature in summer, when you encounter this problem, you will want to solve it as soon as possible. Then, what are the possible reasons that cause the air conditioner to fail to reach the temperature you set or set? Please read on and I will provide a list of possible reasons. And solutions that should help you make your home as cool as you think.

Reasons Your Air Conditioner Isn’t Cooling to or Below Your Set Temperature

AC System Scale is Too Small

AC System

If your air conditioner can not cool your house to the temperature you set, you may have to deal with the air conditioner being too small. Before buying an air conditioner, the technician usually looks at how big your space or house is, and then he will suggest the size of the air conditioner. However, if you do not consider the size of your home, you may eventually buy an air conditioner that is too small or too large.

The cooling power of your AC system is measured in BTU. It is easy to measure the required capacity of your air conditioning unit if you want a mini-split air conditioner or a window air conditioner. When you want a central air-conditioning system, the challenge comes.

Other times, a big air conditioner is installed, but when you decide to modify your home. Expanding your room or house without considering the size of the air conditioner may cause problems. This may cause cooling problems with the air conditioner.

Outdoor High Temperature

If the outdoor temperature is extremely high, it will be difficult for your air conditioning system to cool down your home. The same is true when a heat wave strikes. Air conditioners are designed to operate normally below 92 degrees Fahrenheit. They can only reduce the external temperature by up to 20 degrees Fahrenheit.

So if the temperature outside is 95 degrees Fahrenheit, you can only count on your air conditioner to cool your home to 75 degrees Fahrenheit. Therefore, the excessive outdoor temperature may be the reason why the air conditioning temperature is lower than 74 ℃.

Although you can’t control the outdoor temperature, you can do something to try to reduce the indoor temperature. These include:

  • Turn off heat-generating appliances, such as stoves. Don’t open your oven or stove. Use the outdoor barbecue.
  • Wash clothes or use the dishwasher after the outdoor temperature drops.
  • Spray the condenser unit with a hose

Thermostat Problem


Hand turning a home thermostat knob to set temperature on energy saving mode. fahrenheit units. Composite image between a photography and a 3D background.

The thermostat problem is the most common reason why the air conditioning temperature is not low enough. When you notice that your air conditioner does not reduce the temperature to your set value, check the thermostat setting.

Make sure your thermostat is set to cool. “If the setting is correct, there may be something wrong with your thermostat circuit.

If you have recently changed the thermostat, try checking the wiring again. Ensure that all wires are properly and securely connected. You can also check the line name on your HVAC control panel for reference.

Dirty Air Filter

Air Filter

If the air filters are not replaced or cleaned in time, they may become dirty and quickly become blocked. When this happens, they will prevent your air conditioner from cooling your home.

A dirty air filter may prevent the normal cooling of the air conditioner.

Before the air enters the air conditioning system, the air filter will filter out the dirt and unwanted objects in the air. This ensures that your system works efficiently and that the air blown into your home contains a minimum of harmful substances.

However, a dirty air filter will restrict the flow of air into the air conditioning system, significantly reducing the amount of air entering the evaporator for cooling. This will eventually reduce the cooling capacity of your home. To avoid this problem, you need to clean or replace the air filter regularly.

How often should I change my AC filter?

Most HVAC filters need to be cleaned or replaced every 30-60 days. But it may depend on how often you use the air conditioning system, the quality of the surrounding air, the number of pets, the size of your family, and other factors.

Regularly check the condition of the filter. Some newer air conditioners are equipped with a check filter indicator to remind you when you need to change the filter. Generally, the air filter is located near the return air hole or in the indoor air handling cabinet.

Look at the filter. If it has the color of mud, it’s really time to change your air filter.

Tip: before changing to a new one, be sure to check the size of your fitter to avoid compatibility problems.

Refrigerant Leakage


30559885 – an hvac technician searching for a refrigerant leak on an evaporator coil.

If your air conditioning temperature is below 74 ℃, this may be a sign of refrigerant leakage. Refrigerant (commonly known as Freon) is a chemical used in air conditioning systems to absorb heat from the home and transfer it outdoors.

If the refrigerant in your air conditioning system is insufficient, your air conditioning system will not be able to cool your home. Over time, due to various conditions, your system may leak, which may lead to refrigerant leakage.

How to repair refrigerant leakage?

For ordinary homeowners, repairing an air-conditioning system with a refrigerant leak may be a bit complicated. In this case, if you think your system will run out of refrigerant, this is to contact your local HVAC maintenance service provider.

HVAC professionals usually have special tools to investigate the source of Freon leakage. They will also seal and test the system before injecting refrigerant into the system.

How can I make my air conditioner work effectively?

Replace the air filter regularly

Make sure your air conditioner is adjusted twice in spring and Autumn

Keep the condenser unit clean and free of sundries and other objects

AC Condenser Unit Blocked

 Blocked AC Condenser Unit

Another thing that may prevent the air conditioning unit from cooling is a condenser covered with objects and dirt.

The condenser is part of the air conditioning system and is used to handle the heat extracted from the home. This is done with the help of the condenser fan. The condenser fan draws air from the side, through the condenser coil, and then from the top.

When the condenser is blocked, it will not have enough space ­­­­­­­­ Exhale the hot air from your home.

This will greatly reduce the efficiency of your system, and your air conditioner will not cool your home.

How often should you clean the external air conditioning unit? ­­­­

Cleaning your external air-conditioning unit can be done 2-3 times a year, depending on how fast it gets dirty and clogged.

Dirty condensers are easy to find. If there are leaves and other objects near the condenser, they will quickly accumulate on the condenser and block the fins and coils. This will make it difficult for the condenser fan to draw air from the side.

The condenser unit can be cleaned by:

  • Spray water around with the hose
  • Remove debris around the condenser

Opening Doors and Windows

Opening the doors and windows outward may be the culprit for your air conditioner not cooling to below 74 degrees. This can happen if you use room or window air conditioning. Because the central air-conditioning doors between rooms need to be kept open in order to cool your home evenly.

But in any case, the door to the outside world needs to be closed. When the external doors and windows are opened, the external hot air will flow in and replace the cooler air. This really makes it difficult for your air conditioner to cool down your home.

Make sure the outer door is closed. If there are gaps between windows and doors, they should also be sealed. This can improve the cooling effect of the air conditioner.

Air Conditioner Maintenance Tips

Is there a way to solve your central air conditioning problem?

Do you want to know how to keep your air conditioner in good working condition to avoid the problem of no longer cooling?

Check the Drainage Pipe

Occasionally it is a good idea to plug a wire through the drain to remove any possible obstacles.

Keep the Coil Clean

This includes evaporator and condenser coils, both located in outdoor units.

Over time, they may be blocked by dirt and debris, which will affect their performance, so they should be checked at least once a year. Keep leaves at least 2 feet away, and pay attention to things like dryer vents, leaves, lawn mowing, and more that may block the coil.

Regularly Replace the Filter

This is probably the most important step you can take to ensure that your air conditioner maintains good working order.

Check the proposed replacement schedule on the filter and keep it up to date.

Winter Preparation

In most cases, the air conditioning cover is unnecessary. The condenser is designed to withstand the outdoor environment. So unless you live in a very salty place, like the beach

In fact, the air-conditioning cover is just to steal money. In many cases, it will make your troops rust prematurely.

Make sure you really need a protective sleeve before buying and using it.

Final Thought

Now that you know the possible reasons why your air conditioner won’t cool below 74, we hope you’ve found a solution to this problem. If you’ve tried the tips in this guide and you’re still having the same problem with your air conditioner, it’s best to seek help from an HVAC professional. A professional will solve your problem quickly. thanks for reading.

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