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My AC Won’t Run: How Can I Get My Unit Working?

A white and gray kitchen with an ac that won't run

As temperatures start to rise, most people count on having a working air conditioner. Having a fully functional AC system isn’t just a matter of simple comfort; it can actually be a real health issue, especially on the hottest days of summer. When you turn on the AC, you expect it to do its job quickly and efficiently, which is why if your AC won’t run, it’s a big and urgent problem. The cause of the problem might be as simple as a tripped circuit breaker or a blown fuse, but it could be something more complex and potentially costly to repair, such as a bad motor, burned wiring, a broken thermostat or a refrigerant leak.

The trouble is, most people have no idea their air conditioner is broken until they turn the thermostat down to cool down the house on a warm day and discover that it doesn’t run like it’s supposed to. There are several symptoms that might indicate your cooling system isn’t working properly, such as when the AC isn’t blowing air at all, when only warm air seems to be coming out of the vents or if your system cycles on and off too quickly. Whatever the problem is, you want to know what’s wrong and how to fix it—fast.

To understand why your unit isn’t working properly, you’ll want to understand the basics of how air conditioners work. If your home has central air conditioning, that means you have an outdoor AC unit called a condenser, which contains a condensing coil, a compressor and a large fan on top. The condenser is connected via pipes and wiring to an indoor unit, which is typically located someplace out of the way, such as in the attic or a closet.

The compressor and the condenser work together to pump refrigerant through the pipes to the evaporator coil connected to the inside unit and the blower motor pulls warm air from your home into the ductwork. The refrigerant running through the coil absorbs heat from the indoor air and the newly cooled air is then pushed out into the rooms of your home through registers—the little rectangular grates located in the ceilings or floors of buildings that blow in that refreshing cool air when your AC is working.

So, what should you do when your AC won’t doesn’t blow cold air? Perhaps you turn it on, but nothing happens; or it seems to work, except the air blowing out through the registers never cools down. Maybe the air is cool but distinctly humid, and it cycles on and off too frequently. Let’s learn some ways to troubleshoot your air conditioner problems to determine why it isn’t working, so you’ll know what to do next.

First, if you turn on the AC but nothing happens—the system doesn’t turn on and no air starts blowing out through the registers—it may be simply that your AC’s thermostat is set to a temperature that’s higher than the ambient temperature in your home. In other words, the air in your home may not be warm enough for the AC to kick on. If this is the case, it’s an easy fix: Simply set the thermostat to a cooler temperature to make it turn on. Sometimes, the thermostat itself needs to be replaced; this is something a heating and cooling specialist can help you with.

If your thermostat is in good working order and you’ve set it to a cooler temperature but still the AC won’t run, the issue may be due to a tripped circuit breaker. This can happen when your home’s circuits are overloaded due to too many appliances running at once. To find out whether this is the problem, locate the circuit box in your home and find the breaker that controls the electricity to your AC unit. If it’s in the “OFF” or tripped position, switch it back to “ON” and see if that corrects the issue.

A blown AC fuse or damaged wiring within one of the units can also cause the AC not to turn on. Some handy homeowners can replace a blown fuse themselves, although most prefer to have a professional handle the task, especially if they aren’t certain that this is the cause of their AC issue. Wiring problems are definitely best handled by a licensed heating and cooling professional who knows how to diagnose these issues and make repairs safely and efficiently.

If your AC is running but the air blowing out of the registers is warm instead of cool, it may be that you need to replace the filter. AC filters should ideally be replaced once every three months, or even more often than that if you have furry pets or use your AC frequently. Failing to replace the filter on a regular basis reduces the airflow to your system, which in turn can cause your AC’s evaporator coil to freeze, which can result in your system not producing cool air and other larger problems.

Another possible cause of an AC that blows warm instead of cool air is a system that is low on coolant. Recharging the coolant, or refrigerant, is another job best handled by a reputable professional, since this is a highly technical job, and certain types of refrigerants are subject to regulations. Also, it’s not as simple as just topping off the refrigerant. If your unit is low on refrigerant, this indicates that there’s a leak somewhere in the system. If that’s the case, the refrigerant piping and associated components must also be inspected and repaired or replaced as needed.

If your outdoor condenser unit is dirty—clogged with dirt, dust, pollen, leaves and other debris—that can also cause your AC system not to work properly. Always keep weeds, vines and other vegetation away from your condenser unit to prevent the unit from getting dirty. A bad fan motor on the condenser is another possible cause of a non-functioning AC; this is yet another issue that should be handled by a licensed specialist.

If your AC cycles on and off repeatedly, it may be that your unit is the wrong size for your home. AC systems that cycle on and off too frequently aren’t able to remove humidity from the air efficiently, so even though your AC might be blowing cold air as expected, your home still might not have the cool, dry, comfortable feel that you want it to have. If this is the case, you’ll have to have a heating and cooling professional advise you on whether you need to replace your AC with a unit of the proper size.

Another possible cause of an air conditioner that is blowing warm instead of cool air is that you have an AC compressor that isn’t working. If the compressor in the outdoor unit fails, it can’t circulate refrigerant properly to the inside unit and throughout your home. Unfortunately, a broken AC compressor is a costly repair, and it’s often best to replace the whole condenser unit rather than just the compressor itself.

Two other issues that can result in a malfunctioning air conditioning unit are a failed AC capacitor and a clogged condensate drain line. Keep reading to learn more about the signs of these issues and what can be done to address them.

An AC unit with a bad ac capacitor

Signs Your AC Capacitor Is Bad And What To Do Next

AC compressors are equipped with a part called a run capacitor, which supplies the high-voltage boost the unit needs to start running when the thermostat is turned on indoors, signaling to the AC system that it needs to begin cooling the inside air. The capacitor is essential to the proper functioning of the entire air conditioning system, so when you have a bad AC capacitor, you have a real problem on your hands. But, what are the signs that your AC capacitor isn’t working properly?

If you notice that your AC compressor sometimes has trouble or makes an odd humming sound while starting, this could indicate you have a bad capacitor. Over time, a failing AC capacitor will have more and more trouble starting the system until it finally breaks completely and your air conditioner won’t run. Air conditioner capacitors can go bad for a variety of reasons. Like any piece of machinery, they degrade over time, although they are designed to last for a long time—up to 20 years. Faulty fan motors or compressors can also put extra stress on the capacitor, as can dirty condenser coils, making the capacitor fail sooner than expected.

A licensed heating and cooling specialist can determine whether your AC capacitor has gone bad and can replace it if needed. A professional may also determine what caused the capacitor to fail, if it did so prematurely. It may be that you have another issue within the AC system that led to the capacitor burning out before its time. If so, that issue will need to be diagnosed and resolved as well to prevent the same thing from happening again.

A living room with a gray, reclining couch and red pillows

Condensate Drain Line Clogged: Symptoms And Remedies

If your unit is turning on and shutting back off shortly after, your condensate drain line could be clogged. To investigate the problem on your own, check to see if your AC’s drain pan is full of water or if there is a puddle of water near your unit. If you notice one or both of these things, your drain line could be blocked and unable to send water outside as it’s designed to do.

In a properly running AC system, refrigerant is converted from a gas to a liquid and back again, cooling the air and drawing the moisture out of it in the process. As that process takes place, the drip pan collects excess water that is pulled from humid air and the condensate drain line directs it outdoors. Since algae and mold can build up in the drain line over time, industry professionals recommend flushing the line with hot water, or hot water mixed with either bleach or vinegar, as part of your regular AC maintenance. Doing this on a routine basis can help prevent any buildup in the drain line.

If you have a newer heating and cooling system, it might come equipped with a sensor that will let you know when there’s a clog in your drain line. If not, it’s a smart idea to check the drain pan when you change your AC filter to make sure there’s no water in it that might indicate a clog in the line. It’s also wise to hire a reputable heating and cooling specialist to perform routine maintenance to your home’s AC system. Air conditioning specialists can conduct regular inspections to ensure your unit is running properly, and identify and remedy any problems before they develop into something more difficult and costly to fix.

ABC Can Help Keep Your Home Cool

When temperatures start to heat up, a functioning AC unit can be the difference between comfort and misery. If you’re in need of an air conditioner repair, you can rely on the licensed professionals at ABC Home & Commercial Services. Our specialists will be able to quickly diagnose and fix any problem you may be having with your unit, so you and your family can be comfortable again. We even offer 24/7 emergency services for those problems that just can’t wait.

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