Common Problems Window AC Units Face

by | Apr 26, 2023 | AC Maintenance, HVAC

For people in spaces that are too small to cool with central air or who don’t have central air for other reasons, window AC units carry several advantages. They’re inexpensive and portable—but they’re not without their problems.

We want to keep you cool all summer long. Here are 6 common problems with window units—and how to fix them: 

6 problems window AC units can face


 1. Water leaking from the front

There are a number of different reasons that your window AC unit might be leaking water from the front.

One of the most common causes of leakage is an improperly mounted window AC unit. When your unit is tilted forward, water may flow to the front instead of draining properly into the drain pan and then out through the drain line. Ensure that your AC unit is level.

It’s also common to see issues with the drain line or hole—these can become clogged, which prevents the water captured in the drain pan from properly draining outside. You can generally clean these clogs with a pipe cleaner or a soft cloth.

If your window AC unit is level and the drain line or hole isn’t clogged, you may have a problem with your condenser pump. Condenser pumps can be repaired or replaced, but it’s often more economical to simply buy a new unit (depending on its age). 

 2. Dirty condenser coils

This is one of the easiest problems to solve—but it’s not always simple to identify. Dirty coils can reduce cooling performance, decrease the lifespan of your window AC unit, and increase your energy bills—but the only way of knowing if your coils are dirty is to clean them regularly. Learn more about how a window AC unit works here

We recommend a quick clean once every month or two—about as often as you clean your filter. In fact, your coils are located behind your window air conditioner’s filter. Once the filter is removed, you can clean the thin metal fins using a soft-bristled brush attachment for your vacuum, then wash them gently with a cloth dampened with warm, soapy water. Let them dry before turning your AC back on. 

 3. Breaker tripping

You turn on your window air conditioner and…the power goes out.

Never pleasant—especially not in the Texas heat.

Generally, there are four reasons your breaker might trip when you try to run your window AC unit:

  1. The circuit is overloaded
  2. Your air filter is clogged
  3. Your unit has faulty wiring
  4. An essential component, like your compressor, is malfunctioning

The first two problems you can diagnose and solve yourself. First, clean out your air filter—a soft-bristled brush attachment for a vacuum to clean out dust, then a soak in a bowl of hot, soapy water, a rub down, and a rinse. 

Then, put the filter back into the unit, and move it to an outlet on a different circuit—or unplug some of the appliances on the same circuit as your unit. Now run the unit—if it works properly, the problem was either the circuit or the filter. You can move your AC back to the original circuit (or plug things back in) to test.

After moving circuits and cleaning the filter, if your breaker still gets tripped when you turn on your AC, it’s probably the wiring or a component—and you’ll need repairs or a replacement. 

 4. Air leaks

When there’s a gap between your window and your air conditioner, hot air can leak from outside into your home. This makes your room less comfortable (obviously), but it also makes your window AC unit less energy efficient.

Air leaks can also occur when there are cracks in your unit’s casing or mounting or when it hasn’t been sealed properly. These problems can sometimes be resolved by applying sealant to the casing. It’s important, however, to research the kind of sealant that will work for the plastic used for your particular window AC unit. 

5. Ice formation 

There are a few different reasons why ice might be forming on your window unit. These problems include:

  • Your air filter may be clogged
  • You might have a faulty thermostat
  • Your blower motor may be in disrepair
  • There may be a refrigerant leak

The first problem you can diagnose and fix yourself—clean out your air filter. You need to allow the air conditioner to fully thaw—you can put your window AC unit in a large container (even your bathtub might do). Let it thaw for 24 hours, and remove any excess water from the drip pan. 

 6. The unit cycles on and off too frequently

Units cycle on and off for a variety of reasons, and how often your unit cycles depends on the size of your unit and the size of the room it’s cooling. A poorly sized unit can be the reason that your unit cycles too often. 

When your air conditioner is set too cold, you may also find that the unit cycles. Turning the temperature up a couple of degrees can reduce cycling.

Frequent cycling can also be caused by dirty air filters—and now you know how to clean them out. 

When cycling isn’t caused by any of the above problems, it’s likely your window air conditioner needs maintenance.

What To Do If Your AC Trips The Circuit

If your AC repeatedly trips the circuit breaker, don’t ignore it. This usually indicates an underlying electrical issue. Problems like loose wiring, overloaded circuits and compressor failures can cause tripping. Learn what to check when your AC trips the breaker to address the root cause and prevent damage.

8 Signs Your AC Needs Professional Repair

Don’t ignore warning signs of AC issues. Symptoms like increased energy bills, unusual noises and leaks indicate problems. Addressing problems early prevents further damage. Review these 8 signs your AC needs repair to know when to call a professional and optimize the lifespan of your cooling system.

Keeping your window AC unit optimized

There are a number of tips and tricks for keeping your window AC unit optimized. We’ve actually written a whole article on those tricks—we highly recommend you read it! 

About The Author

John Magninat

John Magninat

Owner John Magninat is a third generation air conditioning repair man. Classic Services Air Conditioning & Heating is a family company with family values and our customers are our top priority.

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