AC Breakdowns in Hot Temperatures Hot summer temperatures can lead to many problems with your air conditioning unit. When the air conditioning is running constantly, air filters become clogged faster than normal. The fan on the exterior unit accumulates debris much quicker.
Not unusual. Most AC systems are only designed to cool your home to about 20 degrees less than the outside temperature - so unless you have a particularly good building envelope (ie lots of insulation and very little air leakage) your AC unit is likely fighting a loosing battle during the worst heat waves.
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:
As we mentioned, air conditioners have a maximum temperature limit. When the temperature outside reaches this point, the AC unit will shut down in order to prevent damage. The reason for this is that when an AC unit gets too hot, it puts strain on the compressor.
Make sure your filter is clean, this will ensure your system is operating at peak efficiency with no airflow restrictions. Cut back shrubbery and anything else that is around your outdoor unit, it needs room to “breathe.” Cook outside on your grill. Avoid heating up the house with the oven if possible.
Temperatures Above 100 Degrees Fahrenheit
Most air conditioning systems are designed to function with outside temperatures of 100 degrees or less. When temps reach above 100, expect lower AC performance and potential breakdowns.
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.
Leaking or Low Refrigerant
The most likely cause of this is a leak. A leak not only keeps the AC unit from cooling properly, but also it can cause other issues within the home. For example, when it isn't cool enough, humidity levels can rise in your home making it feel hotter than it is inside.
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.
Air Conditioners Have Limits
It's true that air conditioners do have limits when the outside temperature is extreme. This means that your air conditioner may be able to keep your home at 77 or 78 degrees when it is 104 degrees outside. But it might not be able to cool it down to 70 degrees during the heat of the day.
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.
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.
For the most efficient performance, set the thermostat 20 degrees lower than the temperature outside. On a 100℉ day, set it to 78℉ to 80℉ to manage utility costs. If there's a lack of airflow, the filter may need to be changed or AC vents cleaned. But it may also mean your air conditioner needs professional repair.
The U.S. Department of Energy recommends setting the thermostat to 78°F (25.5°C) when you are at home and adjusting it higher when you are away. Keep Doors and Windows Closed: To prevent warm air from entering your home and cool air from escaping, make sure all doors and windows are properly sealed and closed tightly.
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.
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.
Yes, you should turn off your AC if it's not cooling.
Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.
In extreme heat, you might notice your air conditioner isn't as effective, and your energy bills could be higher. Here's why: High temperatures put extra stress on the AC, which can lead to parts like fan motors and compressors getting too hot. This can cause uneven cooling or even damage the system.
A common reason your air conditioning unit may not be cooling is due to dirty filters. Pollen, dust, pet dander, and other particles can accumulate on your filter and obstruct airflow. Your system will continue to run but with significantly decreased cooling capability.
Air conditioners make homes more comfortable on hot and humid days. So, it can be frustrating when the AC is not cooling below 75 degrees, even if it has been running for hours. Many factors can cause this issue, including clogged filters, refrigerant leaks and the wrong unit size.
Another problem that can cause your house to be hotter than what you've set the thermostat to is if your home's HVAC system isn't sized properly. An HVAC system that's too large for your house will cool your home unevenly. It will only cool some rooms off and then shut off versus cooling down the entire house.
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.