Should I run my HVAC system during a wildfire?

Wildfires are becoming extremely common in California, and it seems that every year now we have at least a few massive fires. All of these fires put off a huge amount of smoke that can have a dramatic impact on air quality. This air quality problem isn’t just limited to the outdoors, as the smoky air and ash can seep into buildings and result in poor indoor air quality as well. With the recent uptick in major wildfires.

One question we have been getting from our customers more and more often is. Can still run their air conditioning when the air outside is smoky?. The answer to that question is yes, and here are the reasons why.

Why AC Is Safe to Use During a Wildfire

Yes—it’s not only safe to run your air conditioner during a wildfire, it’s actually recommended.
When the air outside is smoky, the most important thing you can do is keep your windows and doors closed. Even if the weather is mild, smoke can quickly seep indoors through any openings and negatively impact your indoor air quality.

This is why it’s essential to keep your home sealed and your AC running during smoky conditions.

Myth: “AC Pulls in Smoke From Outside”

One common misconception is that central air conditioning systems draw in air from outside. This leads many people to believe they should shut off their AC during smoky days.

The truth?
Central AC systems do not bring outside air into your home. They recirculate the air already inside, cooling and filtering it in the process. This makes them an effective tool in keeping your indoor air clean—especially when paired with a high-quality air filter.

You also don’t need to worry about running a heat pump during wildfire conditions. Heat pumps operate on the same basic principles as central AC systems and also do not pull in outside air.

Evaporative Coolers, Portable ACs and Window Units

While central AC systems and heat pumps are safe to use during wildfires, the same can’t be said for evaporative coolers, portable ACs, and some window air conditioners.

Evaporative Coolers (Swamp Coolers)

These units pull air from outside, making them unsafe during smoky conditions. Running a swamp cooler can quickly fill your home with smoke.

Window Air Conditioners

Most window ACs recirculate indoor air, but some draw in outside air for ventilation.

• Turn off the “fresh air” feature if present.

• Seal gaps around the unit to prevent smoke from entering.

Portable Air Conditioners

Both single-hose and dual-hose portable ACs are not ideal during wildfires:

• Dual-hose units bring in outside air—along with smoke.

• Single-hose units create negative pressure, pulling smoky air into your home through cracks and gaps.

How to Overcome Indoor Air Quality Issues Caused by Smoke

Even with doors and windows shut, smoke can still enter your home. This happens through air leaks around windows, doors, walls, and roofs—a process known as infiltration. It’s especially common in older homes with more drafts.

Running exhaust fans (like kitchen or bathroom vents) can also pull in smoky air from outside.

Tips to Reduce Smoke Indoors

✅ Upgrade Your HVAC Filter

Standard filters only trap large particles. For smoke and ash, use a MERV 10–12 filter or higher. These are more effective at capturing fine smoke particles.

🔄 Change Filters More Often

During wildfire season, replace your HVAC filter more frequently to maintain clean airflow and reduce smoke buildup.

🌬️ Use Portable Air Purifiers

A HEPA air purifier can help clean the air in specific rooms. Choose one rated for smoke and particle removal.

🏠 Install a Whole-Home Air Purifier

For the best protection, consider a whole-home air filtration system. These systems filter out:

• Smoke & ash

• Allergens (pollen, pet dander, dust mites)

• Mold spores

• Exhaust fumes & VOCs

Whole-home units provide cleaner, healthier air throughout the entire house—far beyond what a standard HVAC filter can do.

Expert HVAC and Indoor Air Quality Services

If you are concerned about the impact wildfires are having on your home’s indoor air quality, the IAQ experts at Air Max HVAC are here to help. We can perform an indoor air quality audit to determine what specific issues you’re facing and the best way to overcome them.

Our HVAC technicians install, repair and maintain a wide variety of IAQ equipment including air purifiers, air filtration systems, humidifiers and dehumidifiers. We can also inspect, maintain and repair your air conditioning system to help you stay cool. If you’re looking for an alternative to your window or portable AC this wildfire season. We also specialize in central AC installation.

We have locations in Burbank, Beverly Hills, Thousand Oaks and Mission Hills, and we serve customers throughout the LA area. If you have any questions about our IAQ services or need to schedule an AC service appointment, give us a call today.