10 Common Reasons Why Your Air Conditioner Isn’t Working (And What You Can Do About It)

When the heat kicks in and your air conditioner suddenly stops doing its job, you can get frustrated quickly. Many AC problems have simple causes; however, in some cases, there are also simple fixes. Before you reach for the phone to call a technician, read this list of top 10 reasons why your air conditioner may not be working.

1. Thermostat Malfunction

If your thermostat isn’t working properly, your air conditioner won’t know when or how to cool down your home. It could be set to the wrong mode, have dead batteries, or be displaying inaccurate readings.

Fix it: If you're trying to cool your home, make sure your thermostat is set to “Cool” mode and the temperature is set lower than the current room temperature. If your thermostat has a fan setting, choose “Auto” instead of “On” for better efficiency. You can also try replacing the batteries or resetting the thermostat. If you're trying to heat your home instead, switch the mode to “Heat” and set the temperature higher than the room temperature.

2. Tripped Circuit Breaker

Air conditioners use a lot of electricity. If your circuit breaker trips, the AC won’t get power. This is a common issue, especially in older homes, during heatwaves, and times of high demand.

Fix it: Check your electrical panel and flip the breaker back on if it’s tripped. If it keeps happening, call an electrician or HVAC technician to investigate further. If you live in California, you can call Synergy Companies at 1-800-818-4298.

3. Dirty Air Filter

A clogged filter blocks airflow, forcing your AC to work harder and causing your system to overheat or freeze up. It can even lead to a total shutdown.

Fix it: Replace your air filter every season, depending on your usage and household conditions (like pets or allergies).

4. Frozen Evaporator Coil

When airflow is restricted or refrigerant levels are too high, moisture on the coil can freeze, causing the system to stop cooling.

Fix it: Turn the unit off and allow the ice to melt. Then replace the filter and make sure vents aren’t blocked. If the problem persists, you may need a technician to check your system.

6. Blocked or Dirty Condenser Unit

Your outdoor condenser unit needs proper airflow to release heat. If it’s covered in debris, grass, or leaves, your system will struggle or fail to cool.

Fix it: Turn off the power and carefully clean around the unit. Remove any debris and rinse off the coils with a garden hose. If you'd like a professional to do so, you can call for an AC tune up where they'll clean and check all your components to make sure they are working properly during the hot summer months.

7. Clogged Drain Line

Air conditioners pull moisture from the air, and that water drains through a small pipe. If it gets clogged, it can trigger a safety shutoff.

Fix it: Locate the drain line and clear the blockage with a wet or dry vacuum or pipe cleaner. If water is backing up, shut the system down and call a professional.

8. Faulty Capacitor or Contactor

The capacitor starts your AC’s motor, while the contactor controls the electricity to the components of the system. If either fails, your AC won’t turn on or stay on.

Fix it: These parts wear out over time and require professional maintainence and replacement. If your unit makes a clicking sound but doesn’t start, this may be the issue.

9. Leaky or Disconnected Ductwork

If you’re getting little to no airflow in some rooms, the issue may be in your system's ductwork, not the AC unit itself. Holes, disconnections, or poor insulation can affect performance of the system.

Fix it: Have your ductwork inspected and sealed professionally, especially if you live in an older home or notice uneven cooling.

10. Aging or Failing AC System

If your air conditioner is more than 10 to 20 years old, it may simply be wearing out. Older systems are more prone to breakdowns, inefficient performance, and outdated parts.

Fix it: If your unit needs frequent repairs or isn't cooling like it used to, it may be time to consider an upgrade to a more energy-efficient system.

Final Thoughts

While some AC problems can be fixed with a filter change or thermostat check, others require a trained HVAC technician. Regular maintenance can help you catch many of these issues early and extend the life of your system.

If your air conditioner isn’t working and you’ve gone through this checklist, don’t hesitate to schedule a professional inspection with us at 1-800-818-4298.