Why is my central AC not keeping up?

Author: Hailee Thompson  |  Last update: Saturday, October 18, 2025

Your HVAC system has to work harder to keep your house cool, and you're receiving less cold air through your vents. If you have air duct leaks, they may also be getting dirty on the inside. Debris within the ducts restricts airflow and causes the air conditioning system to release dust and other debris in your home.

Is it normal for central air to not keep up?

HOWEVER, your AC not reaching your regular set temperature is often very normal for extreme heat situations and here's why: Your A/C system is sized for the temperatures it will experience 99% of the time, not the extreme 1%.

Why isn't my central air keeping up?

Common causes of airflow problems include dirty air filters, blocked vents, and debris in the air ducts. If you suspect that your airflow is being restricted, it's essential to identify the cause and take action to resolve it. One simple fix for this issue is to replace your air filters.

Why is my central AC not keeping up with 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 won't my AC get colder than 72?

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.

Home AC Not Keeping Up or Struggling to Cool Down Enough

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.

How long should it take to cool a house from 80 to 72?

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.

Is it normal for AC not to keep up in extreme heat?

When the temperature soars, your AC has to work harder to maintain a comfortable indoor climate. It needs to remove more heat from your home, and if it's not properly maintained or appropriately sized for your space, it can struggle to keep up.

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 to tell if a thermostat is bad?

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.

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.

Why is my AC struggling to cool my house?

Proper airflow is crucial for an AC system to cool your home efficiently. Several factors can compromise airflow, including blocked or obstructed vents, closed or incorrectly adjusted dampers, and dirty or obstructed evaporator coils. These issues restrict the air's flow, reducing the system's cooling capacity.

How to check refrigerant level in AC?

Steps for Checking Refrigerant Levels
  1. Turn Off the AC and Remove the Cover. Turn off the AC unit and remove the cover to access the refrigerant level gauge or gauges.
  2. Locate and Remove the Access Panel. ...
  3. Attach Refrigerant Pressure Gauges. ...
  4. Interpret Pressure Levels. ...
  5. Add Refrigerant (if Necessary)

Why is my house still hot with the AC on?

Despite running your air conditioning system, you may still find hot spots in certain rooms of your house—particularly in large rooms or in multi-story homes. This problem can be caused by a variety of factors, such as insufficient insulation, a damaged AC system, or ventilation issues.

How do I reset my central AC not blowing cold air?

Use these tips to reset an air conditioner using the reset button:
  1. Turn your thermostat to the “off” setting.
  2. Turn off the circuit breaker that powers your AC.
  3. Press and hold the reset button for three to five seconds.
  4. Restore power to your AC by flicking the circuit breaker back on.

What to do if your AC can't keep up?

Help Your Air Conditioner
  1. Don't Turn Down The Thermostat. ...
  2. Open Your Vents. ...
  3. Change Your Air Filter. ...
  4. Clean Off The Outdoor Unit. ...
  5. Check Your Home. ...
  6. Close Your Blinds and Curtains. ...
  7. Run Major Appliances in the Evening. ...
  8. Have A Heat Pump Installed.

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

Yes, you should turn off your AC if it's not cooling.

How to know if refrigerant is low?

Warning Signs of Low Refrigerant in Your AC or Heat Pump
  1. Weak Airflow or Warm Air Blowing from Vents. ...
  2. Poor Cooling Performance. ...
  3. Constant Cycling On and Off. ...
  4. Ice Buildup on Refrigerant Lines or Evaporator Coil. ...
  5. Hissing or Bubbling Noises.

Why is my HVAC running but not cooling?

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.

What temperature should my house be if it's 100 outside?

For instance, if it's 100 degrees outside, aim to set your thermostat to at least 80 degrees. Adhering to the 20-degree rule maintains energy efficiency, prevents strain on your cooling system, extends its lifespan, and promotes lower energy bills and consistent indoor comfort.

Why is my AC not keeping up with the thermostat?

Clean your Air Filters, Vents, and Ducts – A clogged air filter will struggle to meet the thermostat's set temperature since the dirt and debris buildup prevents air from circulating through the vents. And as airflow into living spaces drops, so do comfort levels.

What is the most common cause of poor air flow in a duct system?

Obstructed Vent

One of the most common causes for poor airflow is a blocked vent. To properly heat or cool your home, the air needs to be unobstructed. To see if there are any blocked vents, look by the baseboards or on the ceiling. Furniture, bedding, and the vent damper could all be possible obstacles to the vent.

How cool should my house be if its 90 outside?

If it's 90 degrees outside, most people would set their AC to a perfectly comfortable temperature of 68-72°F.

How fast should my central air cool a house?

As a general rule of thumb, a well-maintained air conditioning unit should be capable of lowering the temperature by approximately 20°F within the first hour of operation. However, achieving the desired temperature may take longer depending on various variables.

Why is my AC taking so long to cool my house?

Dirt, dust mites, pet dander, debris, and other buildup can get trapped in your AC filter. Once this buildup reaches a certain point, it reduces your air conditioner's efficiency. This makes the unit work harder to cool down your home, which is why it takes longer to reach the desired temperature.

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