Four Common Misunderstandings About How Your AC Works and How to Use It

Common Misunderstandings About How Your AC Works

At A-Avis, our techs help so many homeowners they have a trained eye for detecting problems common to Southern California air conditioning systems.

Far too often we see problems left unattended for so long they pose a greater threat later down the line. This compromises the system’s performance altogether or even the health of people living in the home.

We believe in empowering clients to make the right choices for their home and central air system. Because of this we’re sharing common misunderstandings about how your AC works.

Problem #1: Homeowners let the heat load get too high

It’s a common habit in Southern California to close the windows and doors for more than three to four hours at a time during peak heat periods. However, this results in no home ventilation.

While homeowners are out, the indoor home temperature can rise considerably. For example, it can be 95° outside and by the time you arrive home the indoor temperature has risen to 88°.

This is an uncomfortable temperature for most families. Turning on the air conditioner is the logical solution, most people set it in between 73° and 75°. Unfortunately, even if the air conditioning never turns off, it may take hours to lower indoor room temperature (as a whole) from 88° to 75°.

When the home gets too hot and the AC must work overtime, the system:

When the home gets too hot and the AC has to work overtime, it:

  • Stresses out the air conditioning system, adding strainItemized Image of a Central Air Conditioning System
  • Expends extra energy
  • Costs more to cool the home now and maintain later


When you know you’ll be out of the house during peak heat hours, leave the air conditioner on to a reasonable temperature (78° to 80°). This allows your AC to run at a sustainable level so that you can adjust the thermostat to a comfortable 75 without stressing out your air conditioner.

Another solution would be to invest in a smart thermostat. This way you can control the temperature from your phone. Leaving the house? Set a higher temperature! On your way home from the store? Lower your temperature from your phone so you’re walking in to a nice, cool home.

Problem #2: A lower number on the thermostat does not mean cooler air

Central air systems work by cooling air 15° to 20° at a time. For example, if the indoor air temperature is 80°, the AC system takes that supply of air and subtracts 15° to 20° of heat before releasing it back into the home air supply. Because it mixes with the other 80° air that has not been conditioned yet, the air is somewhat cooler, but not necessarily the temperature that was set on your thermostat. It takes time for the indoor air to reach temperature equilibrium.

However, if you believe the mixing of temperature treated air and the indoor air supply is not the reason for poorly conditioned air there, may be a greater issue. Though air is still conditioned, it is less efficient, forcing the system to work twice as hard to cool the same amount of air.


If your air is not cooling air in 15° to 20° increments, a maintenance call is required to restore proper function and efficiency levels.

Problem #3: Homeowners ignore filter maintenance

A regularly scheduled maintenance call usually eliminates issues with poor or dirty air filtration. From stuffed filters to debris buildup over the evaporator coils, keeping your central air system clean benefits the system itself and the cleanliness of the air inside of your home.

How Often Should I Change my HEPA Filter

When air filters are not cleaned or replaced it adds excess strain to the AC. This happens because less air gets through the filter and less air is conditioned. This can also cause the evaporator coils to ice up while the system overheats.

Refrigerant, an essential part of the cooling process, flows through the evaporator coil. This coil is made of hollow tubes that are cooled by the refrigerant. This colder temperature triggers the heat transfer process. Meaning any heat from the indoor air is transferred to the evaporator coil and refrigerant.

Something as simple as a dirty filter can stop this process because less room temperature air passes over the coils which in turn ice up.

Likewise, poor air flow due to dirty filters can result in the system overheating and shutting down. This is because a central air system needs a heat source to function, and restricted air flow means the same amount of energy is used for less and less air.

Dirty or overfull air filters are the number one reason a system shuts down.


Have your preferred HVAC technician visit to service your AC system. Be sure to replace filters and have the evaporator coils and drip pans cleaned. These areas collect water and are prone to microbiological growth.

Problem #4: The AC system is not an open system

Most homeowners tend to think their air conditioning system is an open system. This is not the case. Contrary to popular belief, there is no need to refill your refrigerant supply.

In a perfect world, a properly installed system would incur no damage and would never need to be refilled. The idea being that refrigerant is recycled with every use.

Unfortunately, we don’t live in a perfect world and refrigerant leaks happen.

Refrigerant is a harmful substance and should only be handled by an HVAC professional. It can also damage the ozone layer.

Because of these two issues, it’s important you call someone immediately if you suspect a refrigerant leak.

When there is a leak in your refrigerant supply, the system is less efficient because it does not have enough cooling power to work with. If your AC system previously cooled indoor air in 20° increments, it now may be cooling in 10° increments; the air conditioner works harder to treat the same amount of air.


Have your preferred HVAC technician repair the leak, refill refrigerant and recalibrate.