When the Santa Ana winds kick in, Canoga Park gets a familiar combination: hot, dry, gusty air, a higher fire risk across the hills around the West Valley, and in some years a hazy sky full of smoke and ash. Your air conditioner and furnace can either help you breathe easier indoors or quietly pull outdoor smoke into the house. The settings you choose matter more than most homeowners realize.
Cooling By Design is headquartered at 21201 Victory Blvd, Suite 125, Canoga Park, CA 91303. Licensed (#1148982), a certified Mitsubishi Electric Diamond Dealer, with 24-hour emergency service available. Call (877) 702-6654 for filtration upgrades, system checks and emergency service across Canoga Park and nearby neighborhoods.
Why Smoke Is a Real Concern in the West Valley
October is typically when Santa Ana wind season ramps up in Southern California. Strong offshore winds dry out vegetation and can carry smoke and ash for many miles, so you do not need to live next to a fire to feel its effects. Fires like the 2018 Woolsey Fire showed how quickly smoke and ash can reach communities across the West Valley and the surrounding hills.
Wildfire smoke contains fine particles (PM2.5) small enough to reach deep into the lungs. Children, older adults, pregnant women and anyone with asthma, heart or lung conditions are most at risk. The goal indoors is simple: keep outdoor smoke out, and clean the air that is already inside.
Step 1: Know the Air Quality Before You Decide
Check the Air Quality Index (AQI) on AirNow.gov or your local air quality district before opening windows or exercising outdoors. In general, an AQI above 100 is unhealthy for sensitive groups, above 150 is unhealthy for everyone, and above 200 is very unhealthy. When smoke is in the forecast, treat your home as a clean-air shelter rather than a place to ventilate.
Step 2: Set Your HVAC System to Protect You
Close up the house
Shut windows and doors, and avoid running whole-house fans or evaporative coolers that pull outdoor air in. If your central system has a fresh-air intake or damper, set it to recirculate so it reuses indoor air instead of drawing in smoke.
Run the fan continuously
On your thermostat, switch the fan from AUTO to ON during smoke events. That moves indoor air through the filter all day instead of only when the system is heating or cooling. It uses some extra electricity, so return it to AUTO when the air clears.
Use the best filter your system can handle
Filters are rated by MERV. Ratings of 13 or higher are generally recommended for capturing fine smoke particles. Before you upgrade, confirm your filter slot and blower can handle it. A thicker, denser filter in a system not designed for it can restrict airflow and strain the equipment. A technician can tell you exactly what your system accepts. If it cannot take a MERV 13 filter, a deeper media filter cabinet is often the fix.
Change filters more often during smoke season
Filters clog faster when ash and fine particles are in the air. Check yours after any smoke event and replace it when it looks gray or dirty. Our homeowner guide to maintenance you can safely do yourself explains how to check and change filters correctly.
Step 3: Add Targeted Air Cleaning
- Portable HEPA air cleaner: place one in the bedroom or the room you use most, sized for the square footage.
- DIY box-fan filter: a MERV 13 furnace filter taped to a box fan is a widely used temporary option when you cannot buy a cleaner.
- Reduce indoor sources: skip candles, burning incense, frying and gas-stove cooking when outdoor smoke is heavy. Avoid vacuuming without a HEPA filter, since it can stir fine particles back into the air.
- N95 respirators outdoors: if you must go out, a well-fitted N95 helps. Cloth and surgical masks do not stop fine smoke particles.
The Heat Problem: Santa Ana Winds Mean Hot Days Too
Santa Ana conditions often bring heat as well as smoke, which means closing the windows can make the house uncomfortable fast. This is when a struggling AC becomes more than an inconvenience, because you cannot just open the windows for relief. If your system is not cooling the way it should, see our guide on why an AC runs but does not cool. If it quits completely, same-day emergency service is available, and our walkthrough of getting fast AC repair explains what to expect.
After the Smoke Clears: Check Your System
- Replace the filter. A smoke-loaded filter can hold odors and restrict airflow.
- Inspect the outdoor unit. Santa Ana winds blow leaves, ash and debris against the condenser. With the power off, clear loose debris and gently rinse the fins from the inside out with a garden hose.
- Clear vents and registers. Wipe dust and ash from supply and return grilles.
- Air out the house. When the AQI drops back to good, open the windows and let fresh air flush the home.
- Schedule a check if smoke odor lingers. A persistent smoky smell can mean smoke has settled in the filter housing, ducts or a leaky return. If you smell burning from the furnace itself rather than outside smoke, read our guide to the furnace burning smell on first start to see what is normal and what is dangerous.
A scheduled professional visit catches clogged coils, loose connections and leaky ducts before they become expensive. See what is included in a proper AC tune-up, use our HVAC maintenance checklist through the seasons, and ask about maintenance plans that build these checks into your year.
When It Is Time for a Bigger Upgrade
If smoke season keeps being a problem, a whole-home upgrade may be worth considering: a deeper media filter cabinet, an advanced air cleaner, or a new high-efficiency system with better filtration options. Browse the air filtration options on our products page. If you are replacing equipment, check which incentives apply in our guide to LADWP and California HVAC rebates in 2026, and see whether a high-efficiency upgrade makes sense for your home.
Our Service Area
Cooling By Design supports indoor air quality, filtration and HVAC service from our Canoga Park headquarters across:
- Canoga Park
- Winnetka
- Woodland Hills
- West Hills
- Tarzana
- Reseda
- Chatsworth
- Northridge
- Hidden Hills
- Bell Canyon
- Calabasas
- Lake Balboa
- Porter Ranch
- Encino
- North Hills
- Granada Hills
- Topanga
- Van Nuys
- Panorama City
- Mission Hills
- Sherman Oaks
Frequently Asked Questions
Should I run my AC during wildfire smoke?
Yes, if the outdoor air is smoky, run it with windows closed and the system set to recirculate, with the fan on. A clean filter is essential, because a clogged one cannot clean the air or cool efficiently.
What MERV rating do I need for smoke?
MERV 13 or higher is generally recommended for fine smoke particles. Confirm that your system can handle that filter, because very dense filters in a system not built for them can restrict airflow.
Should the thermostat fan be on AUTO or ON during smoke?
ON. Continuous fan operation keeps air moving through the filter. Switch it back to AUTO when air quality improves to save energy.
Can wildfire smoke damage my air conditioner?
Ash and debris can clog the outdoor coil and filters, which reduces performance. Replace the filter and gently clear the outdoor unit after a smoke event, with the power off.
Does opening windows help clear indoor smoke?
Only when the outdoor AQI is good. If the air outside is smoky, opening windows brings smoke in. Wait for conditions to improve, then ventilate.
How often should I change my filter during fire season?
Check it after every smoke event and replace it when it looks dirty. During heavy smoke it may need changing much sooner than usual.
Get Your System Ready Before the Next Smoke Event
Whether you need a filter upgrade, a system check, or emergency help during a heat wave, our licensed team is ready. Browse our frequently asked questions or ask about maintenance plans. Call (877) 702-6654 or schedule online here. Email office@coolingbydesign.com. License #1148982. 21201 Victory Blvd, Suite 125, Canoga Park, CA 91303.