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Nothing helps you fight back against summer heat waves better than a quality window air conditioning unit, but unfortunately not all AC units have been designed to offer the kind of longevity and performance we are accustomed to.

As these appliances get a little bit older and have been through several seasons of cooling, it’s not uncommon for problems to pop up.

Thankfully though, unlike traditional “whole home” air conditioning units, window air conditioners can be cleaned, maintained and run through a proper troubleshooting process without any real difficulty.

This is true even if you don’t have special technical skills or an assortment of tools laying around the house.

Obviously, you’ll want to learn as much about how window air conditioners work so that you can to better understand exactly what you’re getting into when it comes time to fix them.

But hopefully, by the time we’re done with the details in this guide, you’ll have a more fundamental understanding of everything that modern air conditioning units bring to the table so that you can repair them more effectively.

In this window air conditioner troubleshooting guide, we are going to highlight some of the most common problems that you’re likely to run across and their solutions to fix them.

A little bit of maintenance and preventative care can go a long way towards extending the life of these units.

The window air conditioner problems and solutions on this page should help you avoid having to replace this home appliance every couple of years.

Let’s dive right in!

The Main Components That Cause the Most Problems

There are a lot of different moving parts that go into creating an effective window air conditioning unit, but the most common components of these devices that are most likely to fail include:

  • The face panel of the AC unit with the air filtration system
  • The evaporator coil that allows your AC unit to cool your space
  • The fan or the blower system that blows air past the evaporator coil and into the room
  • The thermostat which controls the temperature of the air and the room it’s working in
  • The compressor that moves the flow of air as well as the coolant material throughout the AC unit
  • The condenser coil that converts hot air into cool air
  • The condenser fan that blows hot air from the hot condenser coil out into the outside

These are the elements of your air conditioning unit that will most likely need a little bit of extra attention over time, and these are the components of your device that you’re going to spend the majority of your maintenance on.

Common Problems and Solutions

Q: Are strange noises coming from your air conditioner?

A: If you’re hearing strange noises coming out of your air conditioner, especially any loud or wailing noises, the odds are pretty good that there’s something wrong with an internal part of your window AC unit.

If you hear any troubling sounds, it’s time to take a look.

The unit’s fan belt is the most common culprit in these kinds of problems, and sometimes the fan belt will simply wear out and become dislodged in the back of the unit.

If there is still life in that belt you can simply readjust things, but from time to time you’ll want to replace the belt to improve the effectiveness and efficiency of your AC unit.

Q: Does your window AC unit have an odor?

A: Window AC units that haven’t been run in a while (like those that have been stored throughout the cooler months and over the winter) can sometimes grow quite a bit of bacteria, mold, and mildew in the condenser coils, especially if large buildups of moisture have started to accumulate.

You’ll want to frequently clean out your air conditioner filter, scrub down your compressors from time to time, and generally make sure that your AC unit isn’t building up pools of moisture.

Moisture is a hotbed for the growth for odor-causing bacterial elements.

Q: Is water dripping out of the front panel?

A: The evaporator coil is what causes moisture condensation to form and this is supposed to drain onto a metal pan at the bottom of your AC unit, which then flows outside through a hole or drain tube. If water is dripping out the front panel, then the pan is not sloping correctly toward the back of the unit.

To correct the problem, ensure that your air conditioner is level on the window sill. When the unit is level, the drain pan should be slopped towards the back, allowing the condensation to be expelled outdoors.

Q: Is your air conditioner cycling on and off too frequently?

A: A window air conditioning unit that is constantly cycling on or off can usually be traced back to a thermostat or temperature sensor that is on the fritz and no longer working the way that it should.

Initially, you’ll want to visually inspect to the thermostat and the temperature sensors to make sure that they are positioned correctly (needs to be positioned near, but not touching, the evaporator coil). If a wire is touching the evaporator coil, adjust it so that it isn’t.

If that’s not it, then check to make sure that the thermostat is not blocked by curtains or other obstructions.

Additionally, inspect the condenser coil and make sure that it is not being blocked with fallen leaves or debris, and that the fins are not damaged or bent. If they are bent, then repair the fins with a fin comb.

If none of these solutions work, it may be time to have the unit serviced by a professional. The refrigerant may be low or the thermostat or temperature sensors may need to be replaced.

Q: Is your air conditioner not blowing out cold air? 

A: This problem is a lot more common than you may think and the solution is probably a lot simpler than you’re probably imagining.

The most common causes of your air conditioner not providing cool air are a dirty air filter and a damaged condenser coil.

To fix it, try cleaning the air filter. If that doesn’t help, clean and inspect the condenser coil on the exterior of the unit. If damaged, it may need to be replaced. If the fins are just bent, use a fin comb to straighten them out. This could be all that you need to enjoy cold air again.

Q: Is your air conditioner not turning on?

A: Don’t let an unresponsive window AC unit scare you. Often this window air conditioner problem can be fixed by just plugging back in an unplugged cord from the outlet.

If that’s not the case, check your electrical circuit box for a tripped breaker or blown fuse. Reset the breaker, if necessary, or replace the fuse.

Note: A fuse must have the proper amperage rating for the circuit. Don’t use a fuse with a higher amperage rating than the circuit wiring. For example, never replace an old 15-amp fuse with a new 20-amp fuse.

Q: Is your window air conditioner repeatedly tripping a circuit breaker or blowing a fuse?

A: If this problem is happening to you, then most likely your window air conditioner is overloading the circuit.

Most window AC units are designed to operate on a standard 120-volt, 15-amp circuit. If your device is plugged into an outlet that also has other appliances running on the same circuit, the circuit could be experiencing an electrical overload.

There are two solutions to this problem, one ideal and the other that’s quite cumbersome.

The best thing for you to do is put your window air conditioner on its own dedicated circuit that’s not used by any other appliances. That way there’s no chance of the circuit overloading and tripping the breaker or blowing a fuse. A licensed electrician can set this up for you for around $100.

The other option is to find out which of your other appliances is sharing the same circuit as your window air conditioner. Then, when you want to use the AC unit, turn off or unplug that other appliance while the AC in use.

For appliances that don’t need to be plugged in all the time, this switching technique won’t be a big deal. However, for devices that do need constant power, like a refrigerator, it’s not a viable solution.

Closing thoughts

Hopefully, now you have a better understanding of everything that could go wrong with your air conditioning unit and how to fix it – as well as the details that can be easily avoided with just a little bit of preventative care and regular maintenance.

If you’re dealing with more significant issues that cannot be resolved with the solutions provided in this window air conditioner troubleshooting guide, the odds are pretty good you’ll need expert help – or a brand new unit.

If the latter is the case, we can help you find the best product for your home with our free window air conditioner buying guide.