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9 Common Air Conditioner Problems & How to Fix Them

Common AC Problems

It’s about that time of year where we start to rely on our air conditioners to combat the sweltering heat. A properly working AC unit will keep your home at a temperature that’s comfortable for you to enjoy even on those 90-degree days. That being said, there’s nothing worse than discovering your air conditioner is broken on a scorching summer day.

The best way to avoid this problem is to confront it well before it even happens — and there’s no better time than now. We’ll highlight some common air conditioner problems, how to identify them and what to do should they arise.

Common Air Conditioning Problems

Your air conditioner won’t turn on.

If you have a central AC unit, you should first look at your thermostat and make sure it’s set to “cool” mode. Examine the external wiring and make sure it’s all intact — sometimes, animals can chew on wires and cause damage to your unit. If all looks good, check your home’s electrical wiring for a tripped circuit breaker or blown fuse. Reset the power in your home and see if that fixes the issue.

If none of these solutions fix the problem, your AC may have a broken motor or faulty internal wiring. In this case, you’ll want to call an HVAC specialist for further examination.

Your air conditioner is not cold.

If your air conditioner isn’t blowing cold air, take a look at your thermostat and make sure it’s set to the proper temperature. Try lowering the temperature by a few degrees. If you don’t notice a difference, then you might have a clogged evaporator or condenser. Check both and carefully clean out any dirt or debris you see (make sure to turn off your unit before you do this!). Too much dirt or buildup of debris such as pollen, weeds and leaves can prevent cold air from reaching your home. Make sure your condenser’s coils and fins are properly cleaned in order for air to flow properly. If none of these actions resolve the issue, call a professional.

An air conditioner that doesn’t blow cold air can also signal that the system has a refrigerant leak. Check the line set (copper tube going from indoor to outdoor unit) and look for any areas that are damaged. Also visually inspect the connections at the inside and outside. If there is a large refrigerant leak, you will see a wet spot. An AC tech can also use special dye to identify small leaks.

Your air conditioner fan is not working.

If your AC fan isn’t working, you’ll want to first check your indoor electrical system and make sure you don’t have a tripped or switched off circuit breaker that’s preventing your AC unit from receiving power. Next, check the AC itself. If there is excessive ice buildup, it can cause the fan’s coils to freeze and prevent it from functioning. If that’s the case, you’ll want to shut off your AC system and contact an HVAC professional.

Another reason why your AC fan isn’t working could be due to a faulty fan relay or motor. If you suspect that this is the case, contact an HVAC professional as soon as possible.

You notice mold in the air conditioner.

Mold is a common but serious problem that can be a threat to your family’s health. Unfortunately, it’s not an easy fix and will most likely call for the help of a professional. If you notice mold growing in your air conditioner condenser, contact your local HVAC pro. They’ll know best how to tackle the problem and keep your family happy and healthy.

central air conditioner condenser

Common Central Air Conditioner Problems

Your AC unit isn’t cooling rooms evenly.

If you notice that your AC isn’t evenly distributing cool air throughout your home, make sure your air filters are clean and in good working condition (see our advice on how to clean an air conditioner filter). If it’s been awhile since you’ve replaced them, you may want to install or have someone else install new filters.

If your issue still isn’t resolved, the problem may have to do with your ducts — in which case, you’ll want to call an HVAC specialist.

Another possibility? Your air conditioner may be too small to efficiently cool your home. If that’s the case, you’ll want to replace your AC unit with something more powerful that can adequately distribute cold air throughout your entire home.

Your AC controls are not working.

If your AC controls have stopped working altogether or in some capacity, the problem most likely has to do with your thermostat. Make sure it’s set to “cool” mode — if it’s set to “heat,” the AC will not turn on. Lower the temperature by five degrees and see if there is any noticeable difference. Next, try replacing the batteries and see if that fixes the issue. If your thermostat isn’t battery powered, or if a battery replacement doesn’t resolve the problem, reset the thermostat according to manufacturer instructions.

If resetting the thermostat doesn’t solve the problem, check your indoor electrical system. Make sure your breakers are all set to “on” and be sure to check for any tripped circuits.

If your thermostat still doesn’t turn on, shut off the power and pry open your thermostat. Check the wiring for any loose wires or screws. Put any displaced wires back in place and make sure they are secure.

If your thermostat still doesn’t work, you may need a new thermostat. Total Home Supply carries a wide selection of quality and affordable thermostats, all designed to enhance your personal comfort.

The bottom line: Central AC units are more complex than window or mini split units. It’s certainly worth it to try and diagnose the problem yourself, but any major repairs should be done by a professional.

AC thermostat

Common Window AC Problems

Your AC thermostat control panel isn’t working.

Is your window AC running but its controls aren’t working? First, make sure your AC is set to “cool” mode. Lower the thermostat by a few degrees to see if there is any noticeable difference in temperature. If this doesn’t work, unplug the AC unit and try resetting it.

If your AC controls are still giving you problems, it could be due to an internal parts issue. Most AC manufacturers offer some sort of warranty on their parts — consult your owner’s manual for details. Since window ACs don’t typically provide user access to the interior, an AC tech will have to diagnose and correct the issue accordingly. However, you may be better off just replacing the AC, as hiring a technician to service the unit will likely be more expensive than purchasing a new unit.

Your fan isn’t working.

Your window AC unit fan may not be working for a number of reasons. First, check the AC unit and make sure it’s plugged in. Check your home’s electrical wiring for tripped circuits or anything that could be preventing your unit from receiving power.

If everything looks good on the external side of things, unplug your AC unit and check the fan and filter. Be on the lookout for anything that could be blocking the fan and remove accordingly. Check the filter and examine how clean it is — if it’s too dirty, the AC unit will not correctly operate. Shut off the unit, remove the filter and try cleaning it — or, if it’s really filthy, replacing it.

If replacing or cleaning the filter doesn’t resolve the problem, you may have a problem with your AC control panel, internal control board or some other internal part. Check your manufacturer’s warranty for specifics on parts. If the repair process is too complex, or if your warranty is up, you may be better off replacing your AC unit entirely.

Your AC unit is blowing warm air.

If your AC unit is running but is blowing warm air, first check the filter and coils and clean accordingly — dirty parts can inhibit your AC’s performance.

If cleaning your AC’s interior doesn’t fix the issue, you may have a more complex problem on your hands. Your AC’s controls could be working improperly, or your unit could be low on refrigerant. Whatever the case may be, hiring a professional to diagnose and repair the issue will almost always be more expensive than replacing the unit.

The bottom line: Window AC units are easier to fix yourself and less expensive than central air conditioning systems. While it’s worth it to try and fix your window AC problems yourself, calling a professional to examine and repair your unit will most likely be more expensive than buying a new window AC unit.

air conditioner fan


Some AC problems are easier to fix than others. If you feel overwhelmed by the complexity of a problem, contact an HVAC professional to diagnose and fix the issue. In some cases — especially with window AC units — buying a new AC unit may be a better (and cheaper) option than purchasing replacement parts and paying for a repair.

Consult a trusted professional to determine if replacing your AC system is the right solution for you. And if you do decide to get a new AC unit, be sure to properly recycle your old unit to reduce your environmental impact. If you’re having issues with your heat source as well, check out our article on common furnace issues.

Top Window ACs

Need a new window AC unit? Total Home Supply carries a vast selection of products to keep you cool during those hot summer months. Here are a few of our best-sellers:

Amana’s AH183G35AX Window Air Conditioner  offers 17,000 BTUs of power to deliver cold air on demand. When winter rolls around, this AC doubles as a heater. Shop Amana window air conditioners now!

Friedrich’s CP08G10B Window Air Conditioner  is an Energy Star qualified air conditioner, meaning it meets stringent requirements for energy conservation. At 8,000 BTUs, it’s a great window AC for rooms of about 200 square feet. Shop Friedrich window air conditioners now!

GE’s AEM05LV Window Unit Room Air Conditioner is another Energy Star qualified AC that delivers 5,200 BTUs. It offers a host of features including multiple fan speeds, energy saving mode and an electronic thermostat. Shop GE air conditioners now!

Mickey Luongo

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

14 thoughts on “9 Common Air Conditioner Problems & How to Fix Them”

  1. The hardest thing about finding the problem with your central AC is not having easy access to every part of the unit. The section of this article about window AC problems talks specifically about parts like the fan or the filter, but you can’t easily check those parts of a central unit. I think it is important to do everything you can to understand the problem so that you can give valuable information to the repairmen who come to fix it.

  2. Linda Miller-morford says:

    Can just changing my thermostat or a.c. control make a huge change in my electrical usage? My SMUD bill jumped a $100/mo after I upgraded my thermostat.

  3. Margaux Ford says:

    I’m glad you talked about checking air filters of an air conditioner if cool air isn’t evenly distributed throughout the room. Our ac is only cooling one area of the room recently, and when my husband checked the filters, we found that they certainly need to be replaced. We’ll have to go to a reputable appliance store that has parts for our ac brand. Thanks for the tip!

  4. Carolyn B. Tackett says:

    Great!!. These are the common problems that always happen in the air conditioner. Thanks for sharing the great knowledge with us.

  5. Joy Zendzian says:

    What might the word ‘leave’ mean on my thermostat screen? The system is working hard & I had a friend stay at my place while I went to another friends over night . In triple digits outside -now, but a/c wants to run coñtinuously. Thanks-~
    (Can’t believe it’s ‘haunted’ & wants me to ‘leave’ …LOL) ????????

    1. Mickey Luongo says:

      Leave probably has something to do with a temperature setback for when you are not home. I would recommend checking the manual for your thermostat.

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  9. Robin Lindsey says:

    I have a question?i have a window unit and it is in full sun.Will a canopy over the top help my energy cost?

  10. vicki simpson says:

    i have a amana unit fau and condenser. i have lived in my house for 16 years and in the last month my unit has been running wild to 50 degrees what is the problem?

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