Why Your AC Breaks Down in the Summer & What to Do About It

When the Indiana heat rolls in and your AC throws in the towel, there's nothing worse than being stuck in a sweltering house with no relief. At Lappe Heating & Air, we get calls every summer from folks all over Evansville saying the same thing: “Why does my air conditioner always break when I need it the most?” Sound familiar?

Here’s the deal—summer is prime time for air conditioners to call it quits. But there’s good news! Most of these problems are preventable or at least manageable—if you know what to look for and when to call in the pros. So let’s walk through the most common reasons AC systems break down in the summer—and what you can do about it.

Dirty Condenser Coils

Let’s start outside. Your outdoor unit—where the condenser coils live—is responsible for dumping all the heat your system pulls out of your home. But if those coils are caked in dirt, dust, or grass clippings, your system can’t breathe.

Dirty coils:

• Reduce cooling efficiency
   

• Make your unit work harder
   

• Lead to higher energy bills
   

• Can even cause a full system shutdown
   

Regular maintenance from an HVAC professional is the key here. We’ll clean those coils and check for early signs of damage before the summer heat gets brutal.

 

Low or Leaking Refrigerant

Think of refrigerant as your AC’s blood. It circulates through the system, absorbing heat inside and releasing it outside. If your refrigerant levels are low—because of a leak or a slow loss over time—your system simply can’t cool your home.

Signs of refrigerant problems include:

• Warm air coming from vents
   

• Hissing or bubbling noises near the unit
   

• Frozen coils
   

This is NOT a DIY fix. Handling refrigerant requires certification (and it’s illegal to mess with it without proper training). Call us right away if you suspect a leak—we’ll test, repair, and recharge your system safely.

 

Frozen Evaporator Coils

Yes, it sounds wild, but your AC can freeze—even during the hottest days of summer. The evaporator coil inside your indoor unit absorbs heat. If airflow is restricted or refrigerant is low, the coil can get too cold and frost over.

When this happens, you may notice:

• No air coming from your vents
   

• Ice on the lines near your indoor unit
   

• A strange humming but no actual cooling
   

The fix? Turn off your system and call a technician. We'll safely defrost the unit and figure out what caused the freeze-up.

 

Clogged or Leaky Drain Lines

Your AC doesn’t just cool the air—it removes humidity, too. That moisture exits your home through a drain line. But over time, algae, dust, and grime can clog that line.

If water backs up, it can:

• Trigger a system shutdown
   

• Lead to mold
   

• Damage your drywall or flooring
   

Don't wait until you’ve got water dripping from the ceiling. We inspect and clear drain lines during our routine maintenance visits, so you never have to worry about hidden leaks or clogs.

 

Faulty or Inaccurate Thermostat

Your thermostat is your AC’s command center. If it's misreading the temperature or sending bad signals, your whole system suffers.

Common issues include:

• The system never turning on
   

• Running constantly
   

• Big temperature swings
   

Sometimes it’s as simple as replacing old batteries, but wiring issues or outdated thermostats can also cause havoc. Let us test your thermostat and upgrade you to a smart model if needed.

 

Fan Malfunctions

Your AC has two fans: one inside (the blower fan) and one outside (the condenser fan). If either one breaks down or slows down, cooling efficiency takes a nosedive.

Reasons for fan failure:

• Motor issues
   

• Worn belts
   

• Dirt or debris blocking blades
   

Ignoring fan issues can lead to overheating and potential compressor failure—a very expensive fix. If your unit’s making weird noises or airflow seems weak, call us sooner than later.

 

Capacitor Failure

Capacitors are small but mighty components that help power the motors in your system. They store and release energy to get the fans and compressor running.

Here’s what you might notice if a capacitor goes bad:

• A loud humming from the unit
   

• The fan won’t spin
   

• AC keeps starting and stopping
   

Capacitor issues often occur after lightning storms or as they age. Replacing one is delicate business—you don’t want to mess with electrical components on your own. That’s where our skilled techs come in.

 

Compressor Problems

Think of the compressor as the heart of your air conditioner. If it stops working, your system can’t do its job.

Compressor problems can be caused by:

• Power surges
   

• Low refrigerant levels
   

• Overheating due to dirty coils or fans
   

A compressor repair or replacement can be expensive, so catching issues early is key. That’s why annual maintenance is a must.

 

Duct Leaks and Airflow Loss

Even if your AC is running perfectly, leaky ducts can prevent cool air from reaching your rooms. You’ll feel warm spots in your house, and your AC will run constantly trying to keep up.

Signs of duct issues:

• Inconsistent temperatures between rooms
   

• Whistling noises from vents
   

• Higher than normal energy bills
   

We offer duct inspections and sealing services to make sure every room gets the cooling it deserves.

 

Dirty or Clogged Air Filters

Here’s a quick breakdown of how dirty filters can wreck your summer:

• Restrict airflow to your system
   

• Cause frozen coils
   

• Make your unit work harder
   

• Lower your indoor air quality
   

• Spike your energy bills
   

• Shorten the lifespan of your AC
   

It’s simple: Clean filters = better airflow, lower bills, and cooler rooms. Let us check them for you during a service visit.

 

AC System Short Cycling

If your AC is constantly turning on and off every few minutes, that’s known as short cycling. It’s a red flag.

Causes include:

• Refrigerant issues
   

• Thermostat placement problems
   

• An oversized AC unit
   

• Electrical faults
   

Short cycling not only uses more energy, but it wears your system out faster. We’ll run diagnostics and get to the root of the problem.

 

Excessive AC Noise

Your AC will never be silent, but if it starts making rattling, grinding, or banging noises, something’s off.

We’ve traced noisy systems back to:

• Loose parts
   

• Worn-out motors
   

• Debris in the fan
   

• Duct problems
   

Don’t ignore the noise—it’s your AC crying out for help. Call us to stop the problem before it escalates.

 

AC Won’t Turn On

The most frustrating problem? When your system won’t start at all.

Causes include:

• Tripped breakers
   

• Blown fuses
   

• Faulty thermostat
   

• Electrical issues
   

Instead of guessing, have one of our technicians safely inspect your system and restore power the right way.

 

AC Blowing Warm Air

You turn on your system expecting a chill—and get a wave of warm air instead. That’s your AC saying, “Help!”

Possible causes:

• Refrigerant leaks
   

• Frozen coils
   

• Malfunctioning thermostat
   

• Compressor failure
   

• Dirty filters
   

Whatever the cause, Lappe Heating & Air is here to get your AC back in business.

 

The Bottom Line from the Pros: Keep Your Cool With Lappe Heating & Air

AC breakdowns in the summer are more than inconvenient—they can make your home miserable. But most problems can be prevented with regular maintenance and early intervention. If your system’s showing signs of wear, don’t wait until it fails. Let the pros handle it.

Give us a call at Lappe Heating & Air in Evansville, IN—our team is ready to bring the cool back to your summer.