It’s September, the kids are back in school, the leaves are starting to turn—and yet your air conditioner is still running. If you’re scratching your head wondering why your cooling system hasn’t taken a seasonal break, you’re not alone.
Many homeowners in the Pacific Northwest experience this puzzling scenario. While it may feel like fall, your HVAC system responds to more than just the calendar. In this guide, we’ll break down three key reasons why your AC might still be running into September, how to troubleshoot the issue, and when to call in the experts.
1. Ambient Temperatures Are Still High
Just because fall officially begins in late September doesn’t mean the summer heat disappears overnight. In many parts of the PNW—including Tacoma, Federal Way, and surrounding areas—September often brings several days of 75°F+ weather, especially during early afternoons.
What’s Happening:
Your HVAC system is triggered by indoor temperature—not the season. If your home heats up in the afternoon due to sun exposure, warm air retention, or poor ventilation, your AC may kick on to maintain the thermostat setting.
Fix It:
- Check the forecast: If warm days are expected, the system is doing its job.
- Use passive cooling: Close blinds during peak sunlight, open windows at night, and use ceiling fans.
- Adjust thermostat settings: Raise the target temp by a few degrees during the day to reduce AC use.
A few sunny days can throw off the seasonal rhythm. If the warmth is occasional, your system is likely operating as expected.
2. Your Thermostat Might Be Set Too Low
Sometimes the issue lies not with the AC, but with the thermostat settings. If you’ve set your cooling temperature to 68°F or lower, your AC may continue cycling even when outdoor temperatures feel cool.
Why It Matters:
Thermostats don’t detect outdoor weather—they react to your indoor air. So, even a slight rise inside (due to appliances, electronics, or warm bodies) can activate the AC.
Signs to Watch:
- House feels colder than necessary
- AC runs even during cloudy or breezy days
- Energy bills haven’t dropped despite the season
Fix It:
- Raise your set temperatureto a more season-appropriate level (around 72°F)
- Switch to “Auto” moderather than “Cool” or “On”
- Program a fall scheduleif your thermostat allows it
Still using a manual thermostat? Consider upgrading to a smart or programmable one for better seasonal control.
3. System Lag or Faulty Components
Sometimes, the AC keeps running when it shouldn’t due to mechanical or electrical issues. These aren’t as common but are important to check if your system runs constantly with no weather-based reason.
Possible Causes:
- Stuck contactor relayin the outdoor unit
- Wiring problemscausing delayed shutoff
- Faulty thermostat sensormisreading the temperature
- Clogged air filtersrestricting airflow and causing inefficiency
How to Tell:
- AC runs for long periods without noticeable cooling
- Thermostat is off but system still hums
- There are sudden increases in your utility bill
Fix It:
- Check your air filterand replace if dirty
- Reset your thermostator check for programming errors
- Call for an HVAC diagnosticif problems persist
We offersame-day HVAC inspectionsthroughout the region. Our licensed technicians can identify and fix any AC issue quickly and affordably.
What Customers Say
“Hunt’s Services provided exceptional plumbing and heating service. The team was punctual, professional, and fixed the issue the same day. I was very impressed!” — Janet Estes
“Zachary and Gordon, technicians for Hunt’s Services, did an outstanding job servicing our HVAC unit. They explained everything thoroughly and made sure we were satisfied before leaving.” — Michele Espinosa
“Our dryer was extremely inefficient and would take hours to dry clothes. Hunt’s Services identified and resolved the airflow issue quickly. We’ve noticed a huge improvement since!” — Roshni Srinath
Pro Tips for a Smooth Transition to Fall
September is the perfect time to begin winding down your cooling system and prepping for heating season. Here are a few additional steps to keep your system healthy:
- Schedule an end-of-season AC tune-up
- Clean around your outdoor condenser unitto remove leaves and debris
- Switch to fall thermostat programming
- Inspect windows and doors for leaksthat affect temperature control
Doing these now ensures your system is ready to hibernate—or rebound for surprise warm days.
AC Still On? Here’s What to Do
If your AC continues running well into September or behaves unusually, don’t ignore it. It may be perfectly normal—or a sign of inefficiency or early failure.
Here’s what you can do today:
- Raise your thermostat a few degrees
- Replace air filters
- Monitor usage over a few days
- Schedule an HVAC check-up if symptoms persist
We’re here to help troubleshoot any HVAC concern. With Hunt’s Services, you get:
- Honest diagnostics
- Fast service and flexible scheduling
- Trusted local expertise
Schedule a Seasonal System Check with Hunt’s Services
Explore our fullHVAC Servicesor check out ourCare Clubfor ongoing maintenance and savings.
Don’t wait for a breakdown or a sky-high energy bill. If your AC is acting out of season, our experienced techs can diagnose and fix the issue in no time.
Call Hunt’s Services Today: (253) 533-7500
Orschedule your HVAC tune-uponline.
Stay comfortable. Stay in control. Trust Hunt’s.
