Why Is My AC Not Working? [7 Common Issues BC Homeowners Shouldn’t Ignore]

You crank down the thermostat. Nothing happens.

The fan stays still. The air stays warm. And you're left wondering, why is my AC not working?

Whether you're in Burnaby, North Van, or Kelowna, summer heat waits for no one. And when your air conditioner goes silent on the hottest day of the year, it's not just frustrating—it’s borderline dangerous. A non-functioning AC during a BC heat wave can lead to overheated homes, health risks for seniors or pets, and even structural humidity damage.

So, if your air conditioner isn’t turning on (or worse, blowing warm air), this guide will help you figure out what’s wrong fast.

We’ll walk you through the 7 most common causes of AC failure in BC homes, give you smart homeowner troubleshooting tips, and help you understand when it’s time to call in Eco Pro Heating’s HVAC experts.

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1. Thermostat Trouble (It’s Not Always the AC)

Before you touch anything else, check the thermostat. It might sound too obvious to be the cause, but it's often the source of the issue.

If your thermostat isn’t set correctly, or if the batteries are dead, your AC won’t get the signal to start. In fact, in many cases we see across BC, the thermostat simply lost power due to old batteries, unnoticed display errors, or loose wiring from recent renovations.

What to check:

• Is the screen blank?
• Is it set to cool?
• Is the temperature set lower than the current room temperature?
• Are the batteries fresh?

What to do:

• Replace the batteries
• Make sure the thermostat is clean and free of dust
• Reset it (refer to your user manual)
• Gently tug on the wiring (if accessible) to check for looseness

If that doesn’t work, the thermostat itself may be faulty or outdated. Smart thermostats can provide better control and help avoid these issues in the future.

Learn more about Eco Pro Heating's expert team

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2. Clogged Air Filter

If you’re wondering why is my AC not working, a dirty air filter might be to blame. It can choke off airflow, cause frozen coils or overheating, and even lead to a complete shutdown—while overworking your compressor and fan.

What to look for:

• Is the filter grey, dusty, or clogged?
• Does your home have hot and cold spots?
• Are you hearing unusual whirring or buzzing from the unit?

What to do:

• Turn off the AC
• Remove and inspect the air filter
• Replace it if it’s dark or dusty (even if only 4 weeks old)
• Set a recurring reminder to check every 30–90 days depending on pets, pollen, and wildfire season

Clean filters improve cooling performance, reduce your power bill, and protect expensive AC components.

Learn more about our air conditioning services

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3. Tripped Breaker or Disconnected Power

One of the most overlooked answers to why is my AC not working is a basic power interruption. In BC, it’s often just a tripped breaker or a mistakenly flipped outdoor disconnect switch.

What to check:

• The circuit breaker inside your home (check for a tripped switch)
• The external disconnect switch near your condenser unit
• Damaged or unplugged power cords (especially on portable AC units)
• GFCI outlets in the garage or utility room

What to do:

• Reset the breaker by flipping it off, waiting 10 seconds, then turning it back on
• Ensure all external switches are turned to “ON”
• Try plugging another device into the outlet to confirm it has power

If your breaker trips again shortly after restarting, there could be an electrical fault within the AC that requires a licensed technician.

Book a professional electrical inspection today

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4. AC Unit Is Frozen (Yes, Even in Summer)

A frozen AC unit is a surprisingly common issue during hot weather. And no, it doesn’t mean your system is overachieving—it means something is seriously wrong.

Why is my AC not working? Because it’s working too hard without enough airflow or refrigerant support. That strain causes the evaporator coil to drop below freezing. Moisture in the air then freezes on the coil, and your system seizes up.

Common causes:

• Dirty air filters
• Low refrigerant levels
• Blocked return vents
• Closed interior vents

What to do:

• Turn off the system immediately
• Set your thermostat fan to “on” to help thaw the coil
• Do not restart until all ice is melted (may take 12–24 hours)
• Schedule a refrigerant level check with a certified tech

Get help from Eco Pro Heating’s cooling experts

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5. Faulty Capacitor or Motor

Hearing a clicking or buzzing but your system won’t start? If you’re asking why is my AC not working, the culprit could be a failed capacitor or fan motor in the outdoor unit.

Symptoms:

• Clicking or humming but no fan movement
• Outdoor unit turns on briefly and shuts off
• Fan spins slowly or not at all

The capacitor is like a battery that gives your AC motor its initial jolt of energy. If it fails, your system can’t start. Likewise, the motor itself can wear down over time from debris, overheating, or age.

What to do:

• Do not try to open or test these components yourself (capacitors hold a charge even when powered off)
• Call a qualified HVAC tech for diagnosis and replacement

Let us handle the repairs safely

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6. Clogged Drain Line or Full Drain Pan

When your AC removes moisture from the air, that condensation has to go somewhere. Most systems have a drain line and safety float switch. If either clogs or overflows, it will shut off the entire system to prevent water damage.

Signs of a drain issue:

• Water pooling around your indoor unit
• Musty smells
• Sudden shutoff after long cooling cycles

What to do:

• Locate and empty the drain pan
• Use a wet/dry vacuum on the drain line outlet
• Sanitize with a vinegar flush every 2 months

If left unchecked, a blocked condensate line can cause mold, rot, or drywall damage.

Explore all Eco Pro Heating services

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7. It’s Just Too Old

Let’s face it: no machine lasts forever. If your AC is more than 10–15 years old and constantly needs repair, it may be time for a modern replacement.

Signs your AC might be done:

• Repeated breakdowns in a single season
• High monthly energy bills despite moderate use
• Uneven cooling or constant cycling
• Rattling, banging, or grinding noises

Replacing your AC with a high-efficiency system can:

• Cut energy use by up to 30%
• Improve indoor air quality
• Lower maintenance costs

BC offers generous rebates for heat pump upgrades that provide both heating and cooling in one efficient unit.

See if you qualify for rebates

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Q&A: Why Is My AC Not Working?

Should I try to reset the AC myself?
Yes, after checking the thermostat and power. Turn off the unit, wait 5 minutes, then power back on. If it doesn't respond, call for service.

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Can a dirty filter really stop the whole system?
Absolutely. It reduces airflow, strains components, and can cause freeze-ups or shutdowns.

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What if the thermostat screen is blank?
Replace batteries first. If that doesn’t work, the thermostat wiring or circuit may be faulty.

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Should I try to recharge refrigerant myself?
No. Refrigerant handling is regulated and requires certification. DIY can be illegal and dangerous.

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What’s the lifespan of a central AC in BC?
About 10–15 years. Regular maintenance helps extend it, but many older units lose efficiency or fail during heat waves.

Ask us your AC questions here

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The Bottom Line

If you’re asking why is my AC not working,  don’t wait until it shuts down completely. It’s almost always preventable, and almost always fixable—if you act fast.

Eco Pro Heating is your trusted partner for heat pump repair, installation, and seasonal care in BC. With rebate knowledge, expert techs, and top-tier customer service, we’ll get you cooling again fast.

Book your service now or see rebate options to upgrade your system.