Why won't my central AC go below 75?

Author: Mrs. Vanessa Pagac I  |  Last update: Monday, October 13, 2025

Many factors can cause this issue, including clogged filters, refrigerant leaks and the wrong unit size. While it's possible to troubleshoot it yourself, it is best to contact an HVAC professional for your AC problems.

Why is my AC not dropping below 75?

Your AC might be stuck at 75 due to various reasons like clogged filters, refrigerant leaks, or the wrong unit size. It's best to have a professional diagnose and fix the issue.

Why won't my AC get colder than 76?

Make sure the thermostat is set to the correct temperature and that it is set to "cool" mode. If the thermostat is set too high or is in "fan" mode, your AC won't cool your home effectively. Additionally, check the batteries in your thermostat to ensure they are not dead or low. Clean or replace the AC air filter.

Why is my thermostat stuck at 75?

There are a few possible reasons why your AC unit might not be going lower than 75 degrees. Dirty air filter: A dirty air filter can restrict airflow, which can make it harder for your AC unit to cool your home. If your air filter is dirty, it's recommended to replace it every 1-3 months.

Why is my air conditioner not bringing the temperature down?

One common reason is a dirty or clogged air filter, which restricts airflow and reduces the system's efficiency. Low refrigerant levels can also cause the AC to struggle in reaching the desired temperature, as it affects the cooling process.

Why is my thermostat reading higher than setting?

Why won't my AC go below 74?

Well, certain problems can prevent an air conditioner from properly cooling down your home including: A dirty air filter. A blocked condenser. A refrigerant leak.

Why is my central AC running but thermostat not going down?

There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.

How cool should my house be if it's 100 outside?

For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.

Why is my AC set at 73 but reads 75?

Clean the Thermostat

Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.

Why isn't my AC reaching set temperature?

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.

Why is my AC not getting as cold as it should?

Your AC unit isn't producing cool air as well as it used to because dirty coils may be hindering its ability to remove heat in your home's air. It could also not work properly due to a clogged filter and refrigerant running low, which are also the most common causes why you feel warmer these days.

How often should I change my AC filter?

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.

How to clean air conditioner condenser coils?

These are the steps our technicians take to make your AC's outdoor coil clean and sparkly:
  1. Turn off power to the unit. ...
  2. Check the refrigerant pressure. ...
  3. Remove the outer casing. ...
  4. Rinse the coil down with water. ...
  5. Spray the coil with cleaning chemicals. ...
  6. Re-rinse the coil with water.

Why is my AC room temperature not going down?

To fix an AC not blowing cool air, ensure the thermostat is set to "cool" mode and the temperature is set lower than the current room temperature. Inspect the air filter as a dirty filter can restrict airflow. Ensure the condenser coils are clean and free of debris. Make sure vents are open and unobstructed.

Is 75 degrees OK for AC?

If it's just you and your spouse, you may be fine with the temperature set at 75-77. But if you have kids and pets running around, or you're cooking and using your oven, these things can all raise the indoor temperature noticeably. So, you might find a temperature setting in the 72-74 range more comfortable.

How long should it take to cool a house from 75 to 70?

The Temperature Outside

Most central air conditioners can cool a moderate-sized (3 to 4 bedroom) home by about 5 degrees every 3 hours. This means while it can take no more than a couple hours to lower the temperature to a comfortable range in the fall or autumn, it can take much longer in the summer.

Why is my AC not going below 75?

Many factors can cause this issue, including clogged filters, refrigerant leaks and the wrong unit size. While it's possible to troubleshoot it yourself, it is best to contact an HVAC professional for your AC problems.

Why is the temperature in my house not going down?

The thermostat needs to be recalibrated.

Sometimes, your furnace or AC system won't hit the thermostat temperature because the thermostat isn't correctly calibrated. This can be a common issue with new thermostats, and also often occurs after a power outage or when the thermostat's batteries are running low.

How to tell if a house thermostat is faulty?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

How cool should my house be if it's 110 outside in summer?

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.

How many degrees can central air cool a house?

As a rule of thumb, when it's 95 out, your AC can cool your house to approximately 70-80. Your air conditioner will be able to cool to about 15-25 degrees from the outside temperature.

How long should an AC run to drop 1 degree?

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.

Should I turn off AC if it's not cooling?

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.

How do I know if my evaporator coil needs cleaning?

Here Are Five Telltale Signs That Your AC Coils Are Dirty And Need to be Cleaned
  1. Your electricity bill has been going up. ...
  2. Your unit seems to be running longer for no reason. ...
  3. Your home doesn't feel as cool as it should be. ...
  4. The Coil is Covered in Frost While Running. ...
  5. Higher Indoor Humidity.

Can resetting thermostat fix AC?

Resetting your thermostat is an easy first step in troubleshooting temperature control issues. If problems persist after a reset, you should contact an HVAC technician for additional diagnostics and repairs.

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