It’s hot, and you’d like to sit down and enjoy a cool temperature in your Los Angeles home. Your heart sinks as you realize your air conditioner isn’t turning on. Even after you adjust the thermostat, it simply doesn’t work. What’s causing the issue, and what should you do?

Don’t worry. Before calling up AC maintenance in Los Angeles, walk through these troubleshooting steps. You may be able to fix the situation and get some relief on your own.

What Causes an Air Conditioner To Stop Working?

Your HVAC system is a delicate balance of your thermostat setting, refrigerant action, power supply, and overall cleanliness. If any of these factors fail, the AC may not kick on. So when your AC stops working, here’s how to troubleshoot the problem.

Check the On/Off Switch

It’s painfully obvious, but the entire system will fail to run if the switch is off. You can usually control this from the thermostat box. Don’t kick yourself if you see that the system is OFF — it’s all too easy to hit the OFF button accidentally!

Check the Float Switch

Many AC systems have a failsafe to prevent the system from becoming flooded with condensation. A device called the drain pan collects the moisture and sends it outside. But if the drain pan gets full or clogged, the pipe leading to it will overflow, triggering the float switch. 

Once the float switch comes on, the AC stops running to prevent water damage. Clearing the drain line and pan should fix the issue. You can do this with a wet vacuum.

Check the Power Supply

Like every other appliance in your home, the AC runs on electricity. Therefore, a tripped circuit breaker can cut power to your air conditioner. A circuit can trip if too many appliances are active at once or if a power surge occurs. In any case, it’s often an easy fix. Check the breaker box to make sure that the relevant circuit is ON. If the breaker continues tripping, contact a professional electrician or HVAC service to correct the problem safely.

Check Your AC Filter

Yes, a clogged filter can prevent your AC from working properly. Excessive dirt and dust impede airflow, which means your system can’t effectively circulate and measure air temperature. Change your filter quarterly or monthly if you tend to have a lot of dander and dust flying around.

Check Your Thermostat Settings

Especially if you have multiple people in your household, it’s worth checking your thermostat settings. Is the desired temperature too high to ever trigger the AC to come on? Is there a schedule in place, such as turning off the AC during certain hours of the day?

And again, it may seem obvious, but check the battery if applicable. A battery-powered thermostat needs a good battery to control your system.

Check the Unit’s Interior and Exterior Components

Depending on the type of system, you may have an exterior unit, interior unit, or both. Central AC units have ducts that run throughout your home. If any of these are dirty or clogged, you’ll likely experience an issue.

Clear away any plants or debris from your exterior unit. Be sure that any ducts and condenser coils are clean and unobscured. Check the vents as well — you’d be surprised by how much a layer of dust can impede airflow!

If you’ve gone through all these troubleshooting steps and your AC still won’t turn on, it may be time to call up an HVAC service in Los Angeles.
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When to Book Professional Air Conditioning Repairs

Your External Unit is Filthy Due to Plant Matter or Dirt

If your external unit (the condenser) has gone a long time without cleaning, it will struggle to release the heat collected from your interior unit. This drastically increases its electricity usage, which can trip the circuit breaker. Once the “fins” on the unit get caked in dirt, you usually need a professional touch to clean them without damaging the unit.

To prevent this problem from happening, be sure to schedule a regular AC tune-up or make a habit of cleaning off the condenser.

Your Capacitor Has Failed

Your AC is, sadly, not magical. On hot days, it can only do so much to alter your home’s indoor temperature. If you set the thermostat too low and the system works overtime, the capacitor can overheat, which causes significant damage. Power outages and surges (a common problem in Los Angeles) can also harm your capacity, which is why it’s vital to install a surge protector.

If the capacitor is damaged, DO NOT attempt to repair it yourself. Turn off the AC and call a professional AC installation company in Los Angeles to safely replace the unit. 

Your Power Cord or Outlet Has Died

It happens. All electrical units degrade over time. Even if the circuit is on, your air conditioner requires a consistent, safe power supply to operate. A damaged cord or outlet will disable your unit.

Again, fixing this issue is not a DIY job. Always contact a professional HVAC service that offers a licensed electrician to replace the cord or outlet. 

Your Refrigerant Levels Are Low

An air conditioner cannot cool air without refrigerant. If you suspect the refrigerant levels are low, you can’t simply top it off. There may be a leak, which presents a whole other issue, or the system was incorrectly installed.

In either case, you must contact a reputable AC installation company in Los Angeles to correct the problem. 


An AC that won’t turn on is a common but frustrating occurrence. Often, you can solve the problem yourself and prevent further issues by practicing good AC maintenance in your Los Angeles home. A regular AC tune-up is always a good idea!

That said, certain situations will necessitate a professional touch. Serious air conditioning repairs should only be done by HVAC experts who can bring the correct tools and knowledge. Never attempt to repair electrical equipment yourself as it presents a safety hazard. 

Thankfully, you can get skilled, attentive AC maintenance and installation in Los Angeles by contacting American AC. We’re here to help you get the cool air flowing again in your home!


James Smith

As you can tell from our humble beginnings in 1981, we began as a family-owned business and stayed a locally owned air conditioning and heating company in Los Angeles county for nearly 40 years.