Over time, dust and debris can accumulate on the AC unit's condenser coils, reducing their ability to transfer heat effectively. Additionally, clogged air filters restrict airflow, causing the system to work harder to cool your home.
If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.
A dirty air filter
Your air filter is designed to trap contaminants in the air before it gets pulled into the AC system. But over time that means that your filter gets dirty and clogged. And if a dirty filter isn't replaced, it can seriously limit your AC's cooling power.
When temperatures exceed 100 degrees Fahrenheit outside, setting your air conditioning (AC) to around 75-78 degrees Fahrenheit is generally considered efficient. Here are some reasons for this recommendation:
Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.
Just because the outdoor temperature is above 100, the Ideal temperature to set your AC unit to doesn't change — it's 78 degrees. Higher temperatures in the home are to be expected when the weather is hotter than usual, but your thermostat can still be set the same as if it were a lower temperature outside.
When you notice that your air conditioner isn't cooling, your first action should be to turn it off. This might seem counterintuitive—after all, you want your home to be cool. However, continuing to run an AC that isn't effectively cooling can cause further damage to the system.
If your air conditioner takes awhile, it may be due to dirty air filters, dirty condenser coils, a refrigerant leak, ice buildup, or an AC unit that's just too old.
Setting your air conditioning to 72°F is generally considered a comfortable indoor temperature for many people. It strikes a good balance between comfort and energy efficiency, making it a popular choice for residential settings.
One possible reason your AC is not reaching the set temperature is that the thermostat could be dirty. If dirt, dust, or other debris has accumulated within the thermostat box, it can cause the wires to heat up or other issues. Thermostats are cleaned during routine HVAC maintenance to help prevent this from happening.
How Often Do I Need to Change Out My Air Filter? Generally, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days, or 3 months. That can change based on where your home is located (ex. dusty, dry climates), if you have any pets, and the age of your system and equipment.
Start by making sure you have it set to your desired temperature and that it's switched to the “cool” setting. Next, double-check your vents to ensure they're open and free from obstructions. If that doesn't work, remove your A/C filter, and inspect it for any dust or discoloration.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
On average, an air conditioner running in good condition should take about 15-20 minutes to drop the temperature by 1 degree in a standard-sized room. However, factors like outside temperature, unit size, and insulation quality can affect this timing.
While there are a number of commercially available coil cleaning solutions on the market, air conditioner coils can be cleaned with a solution of a mild household detergent and water. The detergent and water mix is applied to the coil using a low-pressure sprayer.
A popular cause behind an AC that is not cooling is the deficiency of refrigerant or Freon. When refrigerant circulates together with the air, your room will be filled with cool air. If your unit becomes low on the Freon, the air that blows into your room will not be as cooling as before.
If your air conditioner isn't keeping up with the heat, your air filter may be to blame. A dirty air filter can obstruct the airflow path through the unit. Using a dirty air filter can also cause less energy efficiency and more costly utility bills.
Whether you've confirmed for certain that you have frozen evaporator coils, or you just suspect it, you need to turn off your A/C. Then, your coils should be able to defrost, taking up to 24 hours to thaw out. You can also safely dry out the coils with a hair dryer.
Best AC Temperature Settings While You Are Home
As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.
There are benefits to having your air conditioner set to “auto” and “on.” The benefits of the “auto” setting include higher efficiency, lower energy bills, better humidity control, less wear and tear on some components, and quieter running.
What should my AC be set at if it's 90 degrees outside? If the outdoor temperature is 90 degrees, it's recommended to set your thermostat between 75-78 degrees.