Why This Matters
Your air conditioner works hard—especially during the hot, dry summers in Rancho Cucamonga, CA. Unfortunately, even the best AC systems can develop problems over time, many of which are preventable with proper care.
In this guide, we outline 10 of the most common air conditioning problems, explain why they happen, and provide practical steps you can take to avoid breakdowns and costly repairs.
1. Dirty or Clogged Air Filters
The Problem:
When your air filter becomes clogged with dust, pet hair, or pollen, it restricts airflow and forces your system to work harder—leading to reduced efficiency, poor air quality, and even system failure.
How to Avoid It:
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Replace or clean your AC filter every 1–3 months
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Choose the right filter size and MERV rating for your home
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Set reminders during peak seasons (spring and summer)
Need help? Follow our full guide on how to change your AC filter.
2. Refrigerant Leaks
The Problem:
Refrigerant is essential for cooling. Low refrigerant levels due to leaks can cause:
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Reduced cooling power
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Ice buildup on coils
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Compressor failure
How to Avoid It:
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Schedule annual HVAC maintenance to check for leaks
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Look for signs like hissing noises, warm air, or high energy bills
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Never try to refill refrigerant yourself—this requires a licensed technician
3. Frozen Evaporator Coils
The Problem:
Evaporator coils absorb heat from your home. If they freeze, your AC will blow warm air or stop working altogether.
How to Avoid It:
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Keep air filters clean and airflow unobstructed
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Make sure vents are open and not blocked by furniture
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Schedule professional coil cleaning if you see ice forming
4. Electrical Control Failure
The Problem:
AC systems cycle on and off frequently, especially in hot weather. Over time, this can wear out electrical components like relays and capacitors, causing the unit to stop working.
How to Avoid It:
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Avoid constantly adjusting the thermostat
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Use a programmable thermostat to manage temperature changes smoothly
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Schedule annual inspections to check wiring and connections
5. Thermostat Malfunctions
The Problem:
If your thermostat isn’t reading the correct temperature or isn’t communicating with the AC unit, it can cause uneven cooling, short cycling, or no cooling at all.
How to Avoid It:
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Replace thermostat batteries yearly
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Keep the thermostat away from heat sources like windows and appliances
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Consider upgrading to a smart thermostat for better control and energy savings
6. Drainage Issues and Water Leaks
The Problem:
Your AC removes moisture from the air and drains it through a condensate line. If that line gets clogged, water can back up into your home or shut down the system.
How to Avoid It:
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Inspect and clean the drain line every few months
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Pour a cup of white vinegar down the line to prevent algae buildup
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Use a wet/dry vacuum to clear visible clogs at the drain outlet
7. Fan or Blower Problems
The Problem:
Your AC has multiple fans: one to move air indoors and one to expel heat outdoors. If these fans fail, your system won’t cool properly and may overheat.
How to Avoid It:
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Keep the outdoor unit clean and free from debris
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Listen for unusual noises—buzzing, rattling, or grinding
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Schedule regular inspections to catch motor or bearing issues early
8. Dirty or Damaged Coils
The Problem:
The condenser and evaporator coils handle heat transfer. When they get dirty or corroded, efficiency drops and parts wear out faster.
How to Avoid It:
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Keep outdoor units clear of grass, dirt, and leaves
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Gently hose off the unit’s fins each season
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Schedule coil cleaning as part of your annual HVAC tune-up
See our full guide on extending your AC lifespan with maintenance.
9. Sensor Issues
The Problem:
Your thermostat includes a sensor that monitors the temperature near the evaporator coil. If it’s knocked out of position or malfunctions, your system may behave erratically.
How to Avoid It:
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Avoid bumping or tampering with the indoor unit’s components
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Ask your technician to inspect the sensor during seasonal maintenance
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Replace outdated thermostats with reliable, modern units
10. Tripped Circuit Breakers or Blown Fuses
The Problem:
If your AC suddenly stops working, it may be due to a tripped breaker or blown fuse—especially if the system is overworking due to high heat or electrical issues.
How to Avoid It:
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Don’t run heat-generating appliances during peak AC hours
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Replace clogged filters and clean the coils to reduce strain
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Only reset a breaker once—if it trips again, call an HVAC technician
Use our AC troubleshooting guide for more safe DIY steps.
Why Preventive Care Is Key in Rancho Cucamonga
In Rancho Cucamonga, summers are long and hot—meaning your AC runs 6–7 months a year. Without regular maintenance, small issues quickly turn into big problems, especially during a heatwave when service providers are booked solid.
Bonus Tips: Preventive Habits That Keep AC Problems Away
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Schedule annual professional tune-ups in spring
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Keep indoor vents unblocked and outdoor units clear
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Use a smart thermostat to optimize cooling schedules
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Replace your filter before it becomes visibly dirty
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Learn to recognize warning signs early (strange noises, poor airflow, warm air)
FAQs: AC Problems and Prevention
What are the most common AC issues homeowners face?
Dirty filters, refrigerant leaks, frozen coils, and thermostat problems top the list. Most are preventable with regular maintenance.
How can I tell if my AC needs professional repair?
If your AC is blowing warm air, making loud noises, or tripping the breaker repeatedly, it’s time to call a licensed HVAC technician.
Is it safe to try fixing these issues myself?
Basic tasks like changing filters or checking the thermostat are safe. For refrigerant, electrical, or mechanical issues, always call a pro.
Does skipping maintenance really lead to more problems?
Yes. Neglecting maintenance causes wear, reduces efficiency, and can shorten the system’s lifespan by years.
When should I schedule my annual AC tune-up?
Ideally in spring, before peak summer demand. Early service ensures optimal performance when you need it most.
Keep Your System Running Smoothly—The Smart Way
AC issues don’t have to catch you off guard. By learning the most common air conditioner problems and how to avoid them, you can keep your system running efficiently, reduce energy costs, and prevent surprise breakdowns during peak summer heat.
Need a seasonal check-up or expert advice? Visit rc-airconditioning.com to schedule your HVAC tune-up in Rancho Cucamonga today.