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5 Common AC Issues in Summer, and How to Solve Them

As temperatures soar and the country experiences record-setting heat waves, millions of Americans turn to that one appliance that’s indispensable for summer: the air conditioner.

Whether it’s central cooling or a window unit, the humble AC makes it possible to maintain a comfortable indoor temperature despite the searing outside heat. However, what happens when your trusted AC unit breaks down?

Fret not. Here are the common problems that air conditioners experience during summer, and how you can fix them.

Common AC Issues in Summer

Common Issue #1: Lack of Cold Air

The problem:

The AC is on, yet it doesn’t seem to be doing its job. Either the output is not cold enough, or the air conditioner is not blowing cold air at all but merely acting in fan mode.

Possible causes:

  • Dirty filters – Clogged vents and filters can block the airflow, making the AC work harder
  • Overworked fan – The outside fan may be struggling to work
  • Refrigerant leak – Low refrigerant levels can lead to warm instead of cool air

The fix:

Clean the vents and filters, and make sure they are not obstructed

Check if the fan is working properly, and make sure it’s shaded from direct 


Listen for a hissing sound that could indicate a refrigerant leak. If this is the 

case, don’t just opt for a refill. Have a professional AC specialist pinpoint the 

source of the leak.

Common Issue #2: AC Won’t Turn On

The problem:

An AC that blows hot air is one thing, but what if the unit won’t turn on entirely?

Possible causes:

  • Electrical issue – these could be a loose plug, tripped breaker, or blown fuse
  • Capacitor problem – the capacitor is responsible for starting the fan motor and keeping it running, the AC version of the spark plug. A worn capacitor means the fan won’t start.

The fix:

Check the electricals. Ensure the unit is plugged in tight, and there are no breaks in the power cord or tripped breakers and fuses in the panel.

Look at the fan. Insert a stick or screwdriver into the vent, and push one of the blades. If the fan starts and maintains its spin after your push, a faulty capacitor could be the culprit.

Listen for a humming noise. If you hear one but the AC doesn’t run, it could again be the capacitor. Thankfully, AC capacitors are universal, so if you plan to replace the capacitor on your own, all you need to note is the voltage rating and microfarad (denoted by the symbol μF).

Common Issue #3: AC Leaking Water

The problem:

You hear a constant dripping sound when the AC is on, or observe a trickle of water either inside or outside the house. In some cases, there’s also a pool of water that collects in the AC’s external casing, visible through the vents.

Possible causes:

  • Clogged drain – Water generated by the evaporator coils is unable to escape, so it collects in the frame.
  • Faulty condensate pump – For basement AC units, this part pumps the water outside. If it breaks, water pools in or around the unit.
  • Dirty filters – Blocked filters reduce the airflow over the evaporator coil, causing it to freeze and form ice. When the ice melts, the excessive water is too much for the pan to drain.

The fix:

Make sure the drain pan and drain line are free of obstructions like accumulated dirt, sludge or mold.

For basement AC units, check if the condensate pump is functioning properly.

Inspect the evaporator coils for signs of ice buildup. If this is the case, clean the vents and filters to restore proper airflow over the coils.

Common Issue #4: No Airflow

The problem:

The AC is on, the filters are clean, but there is no air at all coming out of the vents.

Possible causes:

This is most likely a fan issue. The fan can cease functioning due to:

  • Dirt buildup over the moving parts
  • Worn belts
  • Broken motor

The fix:

Fans are not user-serviceable parts. To make sure the problem lies with the fan, eliminate other possible causes. Make sure the unit is actually on, all electricals are good, the filters are clean, and the thermostat setting is lower than the ambient temperature outside.

Once you’ve done all these, call an AC specialist to repair or replace the fan or its components.

Common Issue #5: Weird Noise

The problem:

The AC is emitting a high-pitched noise, banging, buzzing or rattling sounds, either upon turning on or after prolonged operation.

Possible causes:

  • Screeching or squealing – Caused by issues with fan or compressor
  • Banging – Could be due to a loose compressor
  • Buzzing – Commonly caused by electrical problems 
  • Rattling – Obstructed airflow or loosened components

The fix:

For high-pitched noises – Inspect the fan, make sure the blades are clean and spinning properly

For banging and rattling sounds – Clean the filters and check for loose components that can be vibrating. If everything is secure, it could be a faulty compressor rattling inside its hermetically sealed casing, which will need to be serviced by a professional.

If you hear a buzzing sound – It could be an electrical issue. Turn off and unplug the unit, then check for loose wiring. A failing motor or capacitor can also emit buzzing and clicking noises and will need to be replaced.

Suffering an AC malfunction in the middle of summer can be a hellish ordeal. As with most things, prevention is better than fixing. So make sure you stay on top of your AC maintenance for a sweat-free season.

Mickey Luongo

Mickey is the resident heating and air conditioning expert with over 15 years of experience in the industry.

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