Millions of homes worldwide have air conditioning systems to make living spaces as comfortable as possible. Most of these units are easy to control with a programmable thermostat, allowing you to set it and forget it.

However, like any other appliance, air conditioning units are prone to wear and tear from regular use, and most will develop problems at some point in their lifetime. It’s helpful to know the fundamentals behind what makes your unit tick in case you need repairs or replacements.

In this guide, we’ll dive into the operation, function and anatomy of residential AC systems and provide some insider advice on how to make DIY repairs.

Here’s a breakdown of topics that we will be covering:

Anatomy of an Air Conditioner

At Above & Beyond Services, our job is to know everything about your air conditioner, so we can troubleshoot issues and service your AC quickly and correctly. Our technicians have years of training and experience specializing in home comfort.

Anatomy of a furnace

When you have a problem with your AC, you can always contact us at Above & Beyond Services. Still, you may be curious about how your central air conditioning system works, and we’re here to help. Here’s a breakdown of some of the major components of your air conditioning system.

Air Handlers

As you might be able to guess from its name, an air handler “handles” and delivers heated or cooled indoor air throughout your entire home, usually via your ductwork. Your air handler consists of an evaporator coil, blower motor, air filter and the electrical and electronic components required to deliver enhanced levels of indoor comfort.

Air Conditioner Compressors

Just like your heart pumps blood throughout your body, the compressor circulates refrigerant throughout the AC system. Refrigerant is the liquid that absorbs heat from inside your home. Eventually, the collected heat vaporizes the refrigerant, which then travels back to the compressor and away from your space.

Evaporator Coils

An evaporator coil is the part of an air conditioner or heat pump that absorbs the heat from the air in your house. It is inside the air handler or blower compartment. The evaporator coil holds the chilled refrigerant that the compressor moves into.


A thermostat is the tool you use to regulate the temperature and control your HVAC system. Most thermostats today are digital and programmable, and use different sensors to detect the temperature in your home. Once you set your thermostat to the desired temperature, it will switch your HVAC system on or off as needed.

Air Ducts

Air ducts are a series of pipes that circulate heated and cooled air through your home through the vents in your floors or ceilings. Properly installed ductwork is an essential part of effective temperature regulation. If you have any gaps, leaks or cracks in your ducts, you can experience significant energy loss via air leakage.

Common Air Conditioning Problems

Though air conditioning systems can be complex, the problems we encounter are often similar. You might be surprised at how simple it is to fix some of these issues yourself. 

Below, we’ll discuss some typical issues that can arise with your air conditioning to prepare you for any AC problem. When in doubt, it’s always best to call the pros for expert diagnosis and repair.

Air Conditioner Problems


Dirty, clogged or otherwise neglected filters are one of the most frequent reasons air conditioners can’t work properly. If your AC is on, but not running to its full capacity, the solution could be as straightforward as changing your filter. Make sure to replace the filter every one to three months, according to the manufacturer’s instructions. Bear in mind that some homes have more than one air filter. If this is the case for you, familiarize yourself with the locations of all of them.


Thermostat settings are another common culprit of air conditioning problems. Thermostats tend to be a set-it-and-forget-it part of your home, especially if you own a digital one. However, if your HVAC system isn’t kicking in or cooling your home to the desired temperature, your thermostat may be malfunctioning. Some cases require a trained technician to fix, but before you call, check that you have your thermostat turned on, that it is on the “cool” setting and that your target temperature is at least a few degrees below room temperature.

Refrigerant Leaks

The refrigerant in your AC absorbs the heat from your home and releases it outside. If your unit is low on refrigerant, you might hear a hissing noise from your system or notice the air conditioning isn’t keeping your home as comfortable as you’d like. Ice formation on the evaporator coils is another telltale sign of a refrigerant leak.

Drain Line

Your AC’s drainage tube is an essential component of your system that removes the water released when the evaporator in your AC unit converts refrigerant from a liquid to a gas. However, over time, this tube can get clogged with algae, mold and other gunk — especially if you’ve neglected regular air conditioner maintenance. One quick way to determine if you have this issue is to check your drain pan, which is typically underneath the unit. If you see standing water in the pan, you likely have a clog. Clearing your clogged drain line is a DIY fix you can do yourself with tools you probably have around the house, but to be on the safe side, it’s best to call a professional.

Breakers or Fuses

Circuit breakers and fuses are a safety feature designed to protect electrical appliances in the event of a power surge. However, breakers can trip and fuses can blow, shutting off power to your unit. If your AC suddenly stops running, one of the first things you should check is the circuit breaker. Always reset a circuit breaker by ensuring that it’s fully in the “off” position first (if not, move it there), then turning it back on. Wait a few minutes and see what happens. If the circuit breaker trips again as soon as your air conditioner turns on, leave it shut off and place a service call.


The capacitors in your air conditioner attach to the motors within the unit, performing the essential function of stabilizing the electrical voltage and providing the power that kick-starts the motors and keeps them running. Faulty capacitors can cause an AC to malfunction in several ways, but the good news is that if you catch capacitor problems in time, your trusted AC technician can quickly swap out bad capacitors for new ones without any long-term damage to your unit. For safety’s sake, it’s best not to attempt this repair on your own because of the high-voltage electricity involved.


Many air conditioner problems originate with the compressor, which supplies energy to the refrigerant that pushes it through the coils. Symptoms associated with a faulty compressor include reduced cooling capacity; a unit that rapidly cycles off and on; a motor that won’t start; and overheating. Bad wiring or a failing motor may be to blame for these issues. A trained HVAC professional can determine the cause of the problem and get you back up and running in no time.

Condenser Coils

Your condenser coil is the other half of the coil system in your AC. Condenser coils work in tandem with evaporator coils to release the heat from your home. Like many other parts of your AC unit, the condenser coil requires regular cleaning to continue functioning properly for the lifetime of your system. This is especially true for the condenser coil, which is part of your outdoor unit and is therefore prone to a buildup of dirt and yard debris. Neglecting periodic maintenance and tune-ups will force each part of your air conditioner to work harder to keep up, which will inevitably lead to premature breakdowns. Overall, AC units with dirty coils usually use up to 40% more energy compared to those with clean coils.

Worn Contactor

AC contactors are small, but crucial, components of your air conditioner. The contactor works alongside the capacitor to keep your AC running smoothly when you need it. Essentially, the contactor is a type of switch that provides power to components such as the compressor and condenser fan and turns the AC unit on and off. A contactor can fail both electrically and mechanically. If your contactor has stopped working, you may hear a loud buzzing sound coming from the unit. You might also notice signs of damage upon a visual inspection.

Troubleshooting Your AC Unit

Common Symptoms to Look For

  • Unusual sounds: If the noises coming from your system have changed, it could signify your unit is no longer working as it should. Maybe components need more lubrication, or something is broken. Acting fast when you notice these unusual sounds can help you prevent further damage.
  • Musty or unusual smell: An unusual smell coming from your AC vents is not good news. It typically indicates hazardous mold growth inside your ductwork or another issue within the AC system.
  • Reduced airflow: If you notice a reduced amount of air flowing through your ducts, this could be a red flag of several different problems. When this issue affects your whole home, it’s quite likely your compressor is failing or needs replacement. If the reduced airflow only affects a few parts of the house, it might be a problem within the ductwork, most likely a blockage. We suggest getting your air ducts cleaned regularly to preserve optimal airflow and prevent mold from growing inside the ducts.
  • Uneven temperature distribution: Any drop in your AC’s performance signifies the need to call a professional. Possible problems include low refrigerant levels or a failed compressor. If some parts of your house are noticeably colder than others, you could have a problem with your thermostat. Our expert techs can effectively diagnose and fix the problem.
  • Moisture near your system: When you see moisture around your AC unit, it could be a sign of either a refrigerant leak or water leaking from the condensation. Leaking refrigerant could pose a significant health risk to you and your loved ones, and needs immediate repairs. Unchecked water leakage could cause a buildup of mold.

What to Check First

Before calling your AC tech when your unit isn’t functioning, start with these four simple troubleshooting tasks. 

  • Check for power: Most AC units draw a substantial amount of power. In an emergency, they have several breakers and fuses to cut them off. If your unit won’t turn on, start by checking your fuse panel and breaker box to see if either have been tripped. From there, you can isolate individual components until you pin down the issue.
  • Check the fans: If the power is OK, or if the breaker continues to trip repeatedly after you reset it, check the AC unit to determine the problem’s source. If the fan isn’t turning on at all, it might be a warning sign the thermostat isn’t functioning properly. There could also be damage to the control unit inside the AC. Of course, unless you’re confident you know what you’re doing, it’s best to leave these repairs up to a professional AC technician.
  • Assess the pump: AC units usually use a pump to eliminate the condensation that forms inside the case. If there’s a lot of water collecting internally, an overflow valve shuts down the unit to protect the unit from water damage. Be sure to check if there’s standing water inside the unit, and whether the pump is running.

Check for temperature drops: If the unit seems to be functioning properly but you’re still not seeing any results, you might have a refrigerant problem. Recharging your home’s AC unit is not a DIY fix, so you’ll need to hire a professional to restore your full functionality.

How to Repair Your Air Conditioning

If you’re relatively handy around the house and have a few simple tools, you can save yourself a potentially pricey service call by doing some repairs on your own. Here’s how.

Tools RequiredMaterials Required
1. Adjustable wrench1. Capacitor
2. Cordless drill2. Compressed air
3. Insulated screwdriver3. Condenser fan motor
4. Multimeter4. Contactor
5. Needle-nosed pliers5. Fuses
6. Nut driver 
7. Socket/ratchet set 
8. Voltage tester 

Step 1: Start With the Easy Fixes

If your AC has suddenly stopped working, don’t panic. You can do a few common-sense things before you pick up the phone and call a professional. First, check all air filters and make sure they’re clean, not clogged. Ensure all the air vents in your floors and ceilings are fully open — these allow airflow to circulate throughout your home. Look at your thermostat — is it set to both “cool” and “auto?” Do you have your desired temperature set several degrees below room temperature? Finally, go outside and visually inspect your unit. Is there any shrubbery or debris blocking the ventilation? Do you hear any strange noises or see ice forming on the unit?

Step 2: Test the Fuses

In the heat of a Delaware summer, we often ask our air conditioners to run nonstop, with no rest periods. Sometimes, this continuous labor causes the unit to overheat, which then triggers a blown fuse. Essentially, a blown fuse cuts power to the system, saving it from further damage. If your AC has blown a fuse, the first thing you’ll notice is that the outside unit isn’t doing anything other than producing a humming sound.

If you understand your AC’s electrical function, you can check for a blown fuse yourself with a multimeter. However, to avoid an electrical shock, make sure you have taken the necessary precautions to ensure your safety. When in doubt, call a trained service pro to check your fuses.

Step 3: Inspect the Access Panel

Faulty wiring is another reason your air conditioner might be failing to do its job. You can check your wiring by opening the AC access panel. After shutting all power to the unit off, remove the screws holding the panel in place. Then, look for any signs of frayed wires or small animal nests. If you are comfortable with the safety protocols for working with electricity, you can repair the wires yourself. Otherwise, it’s best to call someone with the necessary tools, training and experience.

Step 4: Clean the Evaporator Coils

With the power to the air conditioner shut off at the circuit breaker and the unit itself turned off, open the evaporator coil door, removing fasteners as necessary. 

Carefully use a soft-bristled brush to dust off the coil, then spray it with a coil cleaner (available at your local hardware store). After foaming up, the spray will drip into the drain pan. Clean the drain pan with soap, hot water and a little bleach. Then, pour a half-water, half-bleach solution down the drain. To keep the drain clean and prevent algae growth, put a commercially available drain pan tablet in the pan. We recommend completing this task every three months for preventive maintenance.

For coils that are dirty enough to significantly affect your air condenser’s function, your best bet is to schedule a professional AC unit cleaning and maintenance. A trained HVAC tech will arrive at your home with the equipment and material necessary to clean your unit without damaging any of its delicate components.

Step 5: Replace the Run Capacitors

If you’re a confident DIYer, replacing AC run capacitors yourself is a fairly simple repair. First, shut off the power. Then, unscrew the bolts and remove the AC unit’s side panel. Visually inspect the run capacitor, which is a cylindrical component with three terminals on top. If you see the top of it is bulging upward instead of lying flat, it’s time to replace it.

For your safety, never touch the run capacitor without first discharging it. If you are not experienced at safely working with electricity, do not attempt this repair yourself. Always call a professional with the training to handle the job.

Step 6: Replace the AC Contactor

The typical lifespan of an AC contactor is between five and 10 years, depending on how regularly you’ve had your unit maintained. Since this piece is relatively inexpensive and DIY replacement is reasonably straightforward, you can do this repair on your own if you have a can-do attitude. After fully disconnecting all power to your AC unit, disconnect the wires from the contactor and unscrew the feet from the unit. Then, screw the feet on the new part back on the unit and reconnect the wires.

Again, if you are not confident in your electrical safety knowledge, you must call an HVAC technician to make this repair, as it can be very dangerous to work with high-voltage equipment.

Should You Replace or Repair Your AC Unit?

If your home’s air conditioner keeps breaking down and you are making frequent service calls, you might be considering a replacement. Here are some things to consider first.

  • Age of unit: If your AC unit is over 15 years old, having it replaced could be the best option. Otherwise, use the 50% rule – if the repair costs are 50% or more than the value of the unit, it’s more economical to have it replaced. At this point, your AC system is likely to continue needing expensive repairs, and it may cost less each year to replace it with a new, energy-efficient air conditioner.
  • Comfort and convenience: A new AC unit usually comes with a warranty, and generally requires a single visit to install. In comparison, an older unit will require an initial visit to repair the problem, along with subsequent trips to install the replacement parts. You should also consider the air quality coming from your unit. A newer unit will be better at controlling the humidity and temperature of the air inside your home, which means improved comfort and air quality for everyone.
  • Red flags: You might need to replace your AC unit if it consistently creates uneven temperatures around your home even after repairs, it breaks down frequently when you run it more often or if it makes excessive noises, which could be a sign of overexertion.

Call Our Pros Today!

We hope you now have a better understanding of what your air conditioner entails and how all its components should work in concert to keep your home comfortable in hot weather. Remember, if you lack the tools, experience and specialized skills needed to complete a DIY air conditioner repair, call Above & Beyond Services for a speedy response, even in an emergency. Remember, the cost of annual HVAC maintenance is a small price to pay for your peace of mind.

Our BBB-accredited company offers a full range of installation, repair and replacement services. Because we believe nobody should overpay for HVAC service, we’ll give you a free second opinion on your estimate from a competing HVAC company. Contact us at Above & Beyond Services today and let us put our 20 years of experience to work for you. We offer same-day appointments whenever possible, along with our 100% satisfaction guarantee.