How to Fix an Air Conditioner That's Not Working

By Hannah Stephens

July 03, 2025

If you've ever experienced the misery of a nonfunctioning air conditioner on a scorching day, you'll know that diagnosing and repairing AC issues can be expensive. While attempting a DIY air conditioning fix is tempting, you risk making the problem worse if you don't know what you're doing.

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Knowing how to recognize the most common air conditioner problems can help you decide which AC fixes to tackle yourself and when to call a professional. Let's learn the most common reasons for an air conditioner not working and some nifty tricks to resolve them.

Troubleshooting Your Air Conditioner

Air conditioners have multiple components and can develop a wide range of issues, but some problems are more common than others. The following guide explains how to figure out the cause of your AC issues.

Air Conditioner Won't Turn On

If your air conditioner won't turn on at all, chances are you have an electrical problem on your hands. First, try turning the thermostat down to see if it prompts the air conditioner to start working.

If it doesn't, check your electrical panel for a tripped circuit breaker. If you find one, turning it back on should restore power to your air conditioner. However, it's important to determine why your circuit breaker tripped — you could have too many appliances plugged into the same circuit, but it could also indicate a serious electrical problem. A qualified electrician can diagnose the cause and get your electrical system running safely.

Alternatively, your air conditioner could have an electrical fault, such as a broken thermostat or faulty wiring. Attempting this AC fix yourself could be dangerous, so it's safer to call a knowledgeable HVAC professional to diagnose and repair the electrical fault.

AC Blowing Hot Air or Inadequate Cooling

Certain air conditioner problems can cause the unit to produce hot air or fail to cool your house sufficiently. You might suspect an issue if your home feels warmer instead of cooler when you turn your AC on.

Fortunately, fixing this issue is often as simple as changing the filter. A clogged air filter can stop your air conditioner from working correctly, so replacing it can get cold air flowing again. Prevent the problem from recurring by setting a reminder on your phone or calendar to replace your AC filter at least every 3 months.

If changing the filter doesn't work, you may have debris blocking your ducts or air conditioner unit or reduced refrigerant levels. Fixing these issues is beyond the skill level of most DIYers, so you'll need to hire a professional to perform an air conditioner repair.

Leaking Air Conditioner

You may not notice leaks in your air conditioner until it stops cooling your home properly, but some homeowners see pools of water or colorful stains under the AC unit. However, it's worth knowing that most air conditioners produce a little condensation from time to time.

The cause of a leaking air conditioner depends on whether it's losing water or refrigerant. Refrigerant has a vibrant color and often leaks due to worn-out lines and connections. Meanwhile, clogged drainage lines and problems with the condensate pump can cause water to leak from your unit.

You can fix water leaks caused by a blocked drain line by sucking out clogs and debris with a wet/dry vacuum cleaner. If your AC keeps leaking water, an HVAC technician may recommend replacing the condensate pump.

Never attempt to fix an air conditioner leaking refrigerant yourself. AC refrigerant is poisonous, and only qualified professionals can work with it safely. An HVAC technician can fix the cause of the leak and top up the refrigerant levels if needed.

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Frozen Coils

The evaporator coils in your air conditioner contain refrigerant that cools the air in your home. Sometimes, these coils can freeze over, preventing your AC from functioning correctly. You'll likely notice visible ice accumulation around the coils and inadequate cooling when this happens.

Stop using your air conditioner whenever you notice frozen coils. Continuing to run the air conditioner can cause permanent damage to your HVAC system and make your home uncomfortably (or even dangerously) hot.

You can sometimes fix this common air conditioner problem by turning the unit off and allowing the ice to thaw for a day. Alternatively, you can thaw the ice more quickly by blowing it with a hair dryer, but using a high heat setting can damage the unit.

While the ice melts, check the filter. A clogged air filter can interrupt normal airflow and increase the risk of the coils refreezing.

Call an HVAC professional to check your system if the coils keep refreezing when you turn your air conditioner back on. Your technician can repair hidden causes and advise you on how to avoid recurrence.

Strange Smells

Unusual smells from your air conditioner can make your whole house stinky and may indicate a potentially serious problem. Common causes of funky air include clogged filters, mold and electrical faults.

If your AC smells musty, check the filters to see if they're clogged and change them if necessary. You can also try unclogging the drainage line to rid your system of mildew.

Stop using your air conditioner immediately if you smell burning coming from your unit. Electrical problems such as loose wiring can cause smoky smells and increase the risk of a house fire. You should have a professional inspect your system and fix the underlying cause before using your HVAC system again.

Preventing Air Conditioner Problems

Proper air conditioner maintenance helps keep your system running smoothly and may save you money on potentially costly repairs. Follow your manufacturer's instructions to clean or replace the filters, and regularly remove any debris around the coils to prevent the most common problems. Scheduling an annual HVAC tune-up can also help you care for your air conditioner and fix minor issues before they develop into major faults.

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