Don’t Let Small Habits Turn Into Expensive Repairs
Air conditioners are built for years of reliable performance—but even the best systems can wear down quickly if they’re misused or neglected. Unfortunately, many homeowners accidentally damage their AC systems through well-meaning but avoidable mistakes.
This guide explores 10 of the most common air conditioning mistakes and shows you how to correct them, helping you extend your system’s life, improve comfort, and reduce repair costs. Whether you live in Rancho Cucamonga, CA, or a similar hot, dry climate, these tips are your front line of defense against cooling system breakdowns.
1. Neglecting to Change the Air Filter
The Mistake:
Forgetting to replace your air filter is one of the most common (and most damaging) HVAC habits. A dirty filter restricts airflow, forces your system to work harder, and leads to poor indoor air quality.
The Fix:
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Check your filter every month, especially during summer.
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Replace it every 1–3 months, or clean it if it’s reusable.
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Use a filter with a MERV rating appropriate for your system.
Learn how in our full guide on how to change your AC filter.
2. Overusing or Frequently Adjusting the Thermostat
The Mistake:
Cranking the thermostat down to 60°F doesn’t cool your home faster—it just makes your system run longer. Constantly adjusting settings can also cause short cycling and component wear.
The Fix:
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Set your thermostat to 78°F when you’re home.
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Use a smart thermostat to maintain consistent cooling.
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Adjust settings gradually, and avoid large temperature swings.
For efficiency and comfort, follow smart thermostat best practices.
3. Skipping Regular Maintenance
The Mistake:
Many homeowners wait until their AC stops working to call for help. Skipping tune-ups increases wear, reduces efficiency, and often voids warranties.
The Fix:
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Schedule professional maintenance once a year, preferably in spring.
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Ask your technician to inspect coils, refrigerant, fan motors, and the thermostat.
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Keep outdoor units clean between visits.
Discover more in our guide to the benefits of regular AC maintenance.
4. Blocking or Closing Vents to “Save Energy”
The Mistake:
It’s a common myth that closing vents in unused rooms saves money. In reality, this creates back pressure in the system, reducing airflow and potentially damaging the blower.
The Fix:
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Keep all supply and return vents open and unobstructed.
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Avoid covering vents with furniture, rugs, or curtains.
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Consider a zoned cooling system if you want room-specific temperature control.
5. Ignoring Unusual Noises or Smells
The Mistake:
That buzzing sound, musty smell, or short-cycling fan may seem minor—but these are often early warning signs of serious issues like refrigerant leaks or motor failure.
The Fix:
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Don’t ignore new sounds or odors.
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Shut down the system and troubleshoot common AC problems.
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Call an HVAC professional if the issue persists or worsens.
6. DIY Refrigerant or Electrical Repairs
The Mistake:
Refrigerant issues and electrical components should never be handled without proper training. DIY repairs can void your warranty or even pose safety risks.
The Fix:
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Only clean or replace parts the manufacturer recommends for homeowners.
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Leave refrigerant recharging, wiring issues, and internal part replacement to licensed technicians.
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Ask for a professional diagnosis if your AC suddenly stops cooling.
Read about safe, efficient practices in the Energy.gov AC energy-saving tips.
7. Poor Indoor Air Quality Management
The Mistake:
Not monitoring your home’s air quality can overburden your AC system and impact health—especially during wildfire season or in homes with pets or allergies.
The Fix:
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Use a high-quality filter rated for allergens or dust.
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Run exhaust fans when cooking or showering.
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Keep ducts clean and consider a whole-home air purifier.
Explore indoor air quality recommendations from the EPA.
8. Running the AC 24/7 Without Support
The Mistake:
Letting your AC do all the work without help—like shading your home or using ceiling fans—makes it run longer than necessary, shortening its life and spiking your bills.
The Fix:
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Use ceiling fans to circulate cool air (set to counterclockwise).
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Close blinds during peak sun hours to block radiant heat.
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Seal air leaks and insulate windows and doors.
These tips pair well with AC energy-saving tips for summer.
Why These Mistakes Are Common in Rancho Cucamonga
With summer highs often exceeding 95°F, AC systems in Rancho Cucamonga work overtime—making any of these habits especially damaging. Add in dry dust, occasional wildfire smoke, and older home ductwork, and it’s easy to see why preventive care matters here more than ever.
Avoiding these mistakes helps:
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Reduce wear and tear
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Prevent emergency breakdowns
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Improve indoor comfort
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Lower energy bills
FAQs: Avoiding AC Mistakes
Is it bad to close vents in unused rooms?
Yes. It increases system pressure and can damage your ductwork and blower motor. Keep all vents open for proper airflow.
How often should I schedule AC maintenance?
At least once a year—ideally in spring before heavy summer use.
Why does my AC make a buzzing or humming noise?
It may be a failing capacitor or loose electrical connection. Shut off the system and contact a professional immediately.
Can I recharge my AC refrigerant myself?
No. Refrigerant handling requires a certified technician. DIY charging is unsafe and illegal in most states.
What temperature should I set my thermostat in summer?
78°F is ideal for comfort and efficiency. Use ceiling fans to feel cooler without lowering the temp.
Avoid Mistakes. Protect Your Comfort.
Avoiding a handful of small missteps can dramatically improve your air conditioner’s performance, reduce energy costs, and prevent untimely repairs. With proper care—and a few smarter habits—your AC system can stay reliable and efficient for years to come.
Need help with maintenance or system diagnostics in Rancho Cucamonga, CA? Visit rc-airconditioning.com to schedule expert service today.