Common AC Repair & Problems [With Pictures How To Fix]

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How Air Conditioning Works 

First, it’s crucial to understand how your air conditioning system functions. If you do, it’ll be easier to perform DIY fixes. Let’s explain…

After your thermostat senses that your house’s temperature doesn’t match its own temperature display, it sends a signal to your outdoor condenser unit. From there, a device called the capacitor supplies power to your outdoor unit’s compressor and fan. After this happens, refrigerant passes from the condenser to the indoor evaporator coil. The refrigerant’s pressure and temperature are subsequently lowered, which cools the coil down.

Meanwhile, your house’s warm air is pulled in through the return duct and sent through the AC filter. After that, it gets blown over the evaporator coil so the refrigerant can absorb its warmth. Finally, while the now-cooled air is blown back to your house, the refrigerant is returned to the condenser and sent outside by the fan.

After about three hours, your house should achieve your thermostat’s set temperature. Once that happens, the AC automatically shuts off.

Now that you know the basics of the cooling process, we can talk about easy DIY fixes. If you’re aware of these, they could help you save money by avoiding paying for an AC repair. 

Step Two: Turn On Your Indoor Unit’s Power Switch

Equally important, your furnace unit has a power switch on its side or nearby on the wall. It resembles a light switch. Even though you generally don’t use your furnace during the summer, its blower fan and evaporator coil are involved in the cooling process. And the power switch must be on for your air conditioning system to receive the electricity it needs to run.

Knowing that, if there’s no air coming from your vents, locate your furnace’s power switch. If it’s off, you’ll need to turn it back on to get the electricity running again. And if you’re wondering why it was off, someone probably turned it off because they thought it was a light switch.

Step Three: Turn On The Tripped Circuit Breaker

Along with the furnace switch, your air conditioning system receives electricity from your house’s circuit breaker. However, if an electrical surge or power outage occurs, your AC breaker could trip and shut the system off! So, if you don’t hear your AC unit running, inspect your breaker panel. If the AC breaker has tripped, flip it back on.

Step Four: Change Your Dirty Air Filters

When bacteria and other unsafe materials enter your ductwork, filters stop them from reaching your house. These filters need to be changed every one to three months. If not, they could become so clogged that air won’t pass through them. Problematically, a blocked air filter can cause more material to build up in your ducts. If so, it could cause your blower fan to overwork itself and your air conditioning unit to break down.

What's more, if you leave your dirty filters in, this can make it much more likely that bio-growth develops and makes your AC smell musty.

On that note, if it’s been several months since you last changed your filters, inspect them. Are they dark-colored or fuzzy? If so, you need new ones! And if you have trouble putting them in, no worries! SuperTech offers filter changeout services.

Furthermore, if you’re interested, we have another blog that gives more great information about changing your filters.

Step Five: Clear Any Airflow Obstructions

Your house’s return vents pull air into your ducts and deliver it to your indoor unit. Conversely, the supply ducts return the air to your rooms after it gets cooled. Often, homeowners close their vents in rooms they don’t visit as frequently to try and save money. However, this can raise your energy bills and cause problems with your AC unit!

Always keep the vents and registers open in all your rooms. Furthermore, check if they’re blocked by large items such as furniture. That can restrict airflow even more!

Step Six: Turn The Condenser Disconnect On

You’ll see a box on the wall connected to your condenser outside your house. This is the disconnect, and it cuts power to the condenser during an emergency so it won’t get damaged. Therefore, if your AC isn’t cooling your house, go outside and open the disconnect. If its power gets deactivated, turn it back on.

While doing this, check if the wires inside the box are burnt or loose. If so, DO NOT try to fix them. Rather, schedule an appointment for SuperTech to come out and perform an AC repair for the wiring.

Is Your AC In Trouble? Call SuperTech To The Rescue!

Malfunctioning Thermostat 

If no cold air comes from your vents, your thermostat’s cooling signal may be blocked. Fortunately, many newer thermostats can alert you when they have an issue. Specifically, they will name a problem or say “Error” on their display. Furthermore, bad wiring, improper programming, and old age can lead to thermostat problems. To learn more, read our blogs on why your thermostat isn’t working and reasons for your thermostat not reaching its set temperature.

Additionally, you could open your thermostat and look at its control board. The board or wires must remain clean for the cooling transmission to work. Beyond this, a dirty board can cause your AC to start and stop if it periodically interrupts the signal inconsistently.

Which brings us to…

High Voltage Wire

Bad Low Voltage Wire

Thermostats have low voltage wires. They are control centers that tell your condenser to run. If they become damaged, they may be unable to provide that command to your condenser. As a result, the cooling process won’t begin.

Failed Compressor

The compressor is inside the condenser. As the name indicates, it “compresses” your system’s refrigerant into vapor before moving it to the evaporator coil. In turn, the coolant can remove heat from your home’s air. Without properly compressed refrigerant, your house can experience a number of major AC repair issues!

Equally important, the compressor is the main sound you’ll hear when your condenser runs. So if its noise stops, the compressor clearly has a problem. Beyond this, other signs are the air in your rooms not being cold enough and your circuit breaker repeatedly tripping. Elaborating further, reasons for your compressor not working include shutting down for safety reasons, a dirty condenser coil, improper refrigerant levels, electrical problems, and a failed capacitor.

Fortunately, we have a blog that discusses reasons for your compressor not turning on! 

Dirty Coil Not Expelling Heat

After the refrigerant returns to your condenser, the heat it took out of your house’s air gets expelled through the condenser’s coil. Problematically, though, filthy material can coat the coil, causing hot air to get trapped inside. In that case, your house won’t be able to cool down. Furthermore, the coil may leak.

Understandably, the best way to avoid a dirty coil is to give your condenser plenty of space. To provide it with more breathing room, install it at a minimum of two feet’s distance away from anything. Otherwise, it may be at risk of getting covered in dirt.

Additionally, if you remember SuperTech’s yearly cooling maintenance, our technicians will clean your condenser!

Damaged Condenser Fin

Around your condenser, you can also see the fin, or the thin wavy wires going up it. Unfortunately, if the fin gets bent and damaged, it could prevent heat from leaving the unit. In turn, your house won’t cool down and your energy bills may increase.

The fin must be restored to the proper position before these issues disappear. Similar to how you comb your hair, a technician can use a comb to straighten it. That said, depending on the severity of the damage, the fin may be either unfixable or not worth repairing. You may need to replace the condenser coil or the entire unit to prevent wear and tear from occurring to the compressor.

Condenser Fan Not Spinning

If you look through the top of your condenser, you’ll see the fan inside. After the refrigerant returns to the condenser, the fan blows its heat outdoors. To your knowledge, feeling warm air blowing from your vents is a huge reason to check on the condenser. Correspondingly, the condenser can’t expel warm air if the fan cannot spin.

Often, your condenser fan is not spinning because of its motor. However, the blades may also get coated in sludge, adding so much weight that they can’t turn. This could result from a lack of maintenance if you didn’t know. Furthermore, you may find that a tree branch has snapped off and fallen into the condenser. If so, it can block the blades’ path.

To continue on that note about the fan’s motor…

Broken Condenser Fan Motor

A motor powers your condenser fan’s blades. So, if the motor has a problem that stops the fan from blowing hot air out of the condenser, you won’t hear it spinning.

Speaking to that, causes of a broken fan motor include physical damage, capacitor or contactor issues, and - for older systems - a loose or broken belt. And, like with the fan blades, a tree branch falling into the condenser can also damage the motor.

Pressure Switches Cannot Alter Refrigerant Pressure

Though not featured on all systems, some condensers have high and low-pressure switches. They read, respectively, to see if the refrigerant pressure has gotten too high or low. If so, they shut your system down so it doesn’t run on incorrectly pressurized coolant.

When the refrigerant returns to the proper pressure, the switches turn the system back on. And in more severe cases, if one of the switches senses incorrect refrigerant pressure five times in a row, it permanently shuts your AC down. If this happens, it may be because refrigerant is leaking from your AC. Until you fix the leak, you shouldn’t let your AC run!

If the high or low-pressure switch malfunctions and can’t shut your system down, your AC won’t cool your house correctly. As a result, you may feel extremely hot indoors.

Service Valve

The service valve is at the bottom of your condenser. It allows the refrigerant to flow from your condenser to the indoor unit without stopping the AC process. This component mainly exists for HVAC professionals to service your system if necessary. For that reason, homeowners should not have to worry about service valve issues harming their cooling systems.

The service valve could get damaged if something falls onto or slams into it. But of course, this shouldn’t cause your AC to experience significant problems. Unless a technician tells you, you may not even know you have a broken service valve!

Blocked Filter Drier

The filter drier absorbs excess moisture and material inside your AC to keep it from breaking down. If the filter gets coated in too much residue, it can become blocked and unable to absorb any other moisture or debris. This could severely damage your system and lead to it needing repair. Your house being too warm is one sign of a clogged filter drier. 

Also, keep in mind that homeowners cannot inspect filter driers themselves. Instead, they’ll need a technician to check them with a clamp.

Faulty Accumulator

An accumulator exists inside a heat pump condenser that links to an indoor air handler, as well as systems with unusually long refrigerant lines. Critically, it’s a safety device for the compressor that catches and removes excess refrigerant so the compressor won’t flood. Furthermore, it blocks oil from reaching the high-pressure switch to prevent unrepairable damage.

If your accumulator rusts, it can stop working and create a refrigerant leak. Refrigerant leaks add wear and tear to your condenser and can damage its compressor. If that happens, it won’t just stop your house’s air from cooling. Additionally, you could hear your condenser making hissing and bubbling sounds! However, those noises will only occur while refrigerant is still inside the system; if the substance empties, there will be no noise.

Any of this will require a heat pump repair.

Speaking of refrigerant…

Refrigerant Leaking

Refrigerant repeatedly flows in and out of your system. Unlike gasoline in a car, it’s not supposed to get used up. The same refrigerant is used for every AC cycle. So, if your system is low on refrigerant, it can only be due to a leak in its line. In this situation, warm air may blow into your house. If so, your AC won’t be able to cool your home correctly.

Beyond this, low refrigerant cannot get correctly pressurized, meaning heat won’t leave the condenser. Also, refrigerant leaks can freeze your evaporator coil, keeping the refrigerant from changing to vapor and absorbing heat from your house’s air.

Other signs of refrigerant leaks are increased energy bills, your indoor unit hissing or bubbling, no air coming from your vents, and your AC short cycling (repeatedly turning on and off). Furthermore, common causes of leaks are poorly-designed refrigerant lines, physical damage to the line, your condenser vibrating too violently, and acidic fluid eroding the line.

Refrigerant problems can lead to numerous AC repair troubles. Visit our blog about freon leaks to learn more. Additionally, if you have an older system leaking refrigerant, it likely uses a type of coolant called R22 freon. Importantly, this substance is facing a shortage and is expensive to refill due to being banned from production in the United States. If you want to learn more, we have a blog on R22 freon as well.

Failed Capacitor

Your condenser must receive electricity from the capacitor to run. So, if it becomes damaged and cannot provide that power, the cooling process won’t occur. Correspondingly, your utility bills could rise. Also, the condenser may start making humming noises. Here, the AC repair problem may be that you need your capacitor replaced.

Damaged Contactor

The contactor is another component inside your condenser that helps turn the unit on and off. However, it must stay closed for electricity to flow from the capacitor to the compressor and fan motor. If it’s open, electricity cannot get through. Therefore, if your AC condenser cannot start, it may be because the contactor is open, corroded, or damaged. If so, you must fix or replace it before cold air starts blowing again.

Restricted Metering Device

As mentioned in the video at the beginning, the metering device (also called the “expansion valve”) is inside your furnace. After the indoor unit receives the refrigerant, this component decreases its temperature and pressure before allowing it to enter the evaporator coil. There are two types of metering devices. The piston is a fixed device, while the TXV adjusts itself according to the superheating method, which involves adding heat to the refrigerant above the substance’s boiling point.

Sometimes, the metering device gets restricted by too much foreign material, closed too tightly, or coated in sludge due to compressor burnout. These situations can block the refrigerant’s path from the compressor to the evaporator coil. This can lead to no cold air blowing or the condenser making bubbling sounds.

Leaking Evaporator Coil

Your evaporator coil may have an issue if warm air, unusual noises, or weird smells coming from your vents. More specifically, it could rust, creating a crack for refrigerant to leak out of. Of course, cracks in your evaporator coil will need sealing, or you may need to replace it. Regardless, your house won’t cool down with cracks present.

Beyond this, your coil could get covered in dirt or freeze due to low refrigerant or dirty filters. If so, it may prevent heat from getting pulled out of your house’s air. The coil could break permanently if it stays that way for too long. This will also stop your AC from working, creating a pretty significant AC repair issue.

Blower Fan Not Spinning

That's right! Your system has two fans that can create a boatload of AC repair problems.

The blower is also inside your indoor unit, toward the bottom. If it’s not spinning, your house’s air cannot get pulled into the system.

To be clear, you should hear the blower spinning while the indoor unit runs. So, if you don’t hear it after setting your thermostat, it’s not running. Additionally, the fan may have a problem if it makes thumping, scraping, or grinding noises. Further, your system may begin short cycling due to blower fan problems.

Blower Motor Is Broken

Like your condenser fan, your blower’s blades spin due to a motor. So, if you don’t feel cold air coming from your vents, listen to your furnace unit. If you don’t hear the fan, its motor may be broken.

The blower’s motor often breaks because it’s dirty or working too hard. This may result from duct holes or obstructions keeping your house from reaching the right temperature.

To help you out, we have another blog that elaborates on issues with your condenser and blower fans not working! 

AC Circuit Control Board Is Damaged

Your HVAC control board is another component inside your furnace unit. It should be behind the access panel, in front of the blower. Critically, this board supplies voltage to the unit and activates the blower after receiving the thermostat’s cooling signal.

So, if the control board stops working, the cooling process will too. Notably, a clear indicator of this is not hearing the blower, as it cannot receive the power it needs to run. No control center is a pretty significant AC repair complication.

Furthermore, if your HVAC system is leaking, shut it off and wipe up the water. If the leak spreads further, it could reach the control board and cause it to rust. If that happens, it may create unrepairable damage.

Ductwork Holes Or Restrictions

Over time, your house’s ductwork may develop holes. Helpfully, the easiest way to determine if it needs patchwork is if certain rooms become unusually cold. If so, it could be because air is escaping from those openings. Leaky ductwork may develop from age but can also occur if items are stored on or pressed against it.

Beyond this, you may experience duct restrictions that stop balanced air distribution throughout your home. These can result from blockages or the ducts being too small. Whatever the cause, it could lead to your blower motor working harder to try and push air into your rooms. In turn, your energy bills may increase and the blower motor may break! Furthermore, duct restrictions can damage components other than the motor.

For a more elaborate guide to what’s in your ductwork, check out our blog on the subject. 

Clogged Condensate Drain Line

Your furnace will only have a condensate drain line, drain pan, and condensate pump if it is “high-efficiency” and produces condensation when it runs. If yours has one, it runs through the wall to connect your furnace to your outdoor PVC pipe. Importantly, the line catches water that forms from condensation and transfers it to the drain pan.

In terms of signs, water leaking around the base of your furnace may be due to a clogged line. If that’s the case, it can weigh down the drain pan and stress the line’s connection. As a result, your system may wear out, or the line and pan may get disconnected. Also, the line may break open and leak, activating the water safety switch and shutting off your system.

Cracked Drain Pan

Depending on what your system’s drain pan is made of, it may be prone to rusting and cracking. If it cracks and water leaks out, the water safety switch will shut your AC down. Furthermore, too much water accumulates inside the pan may overflow and leak. For more information on drain pans, visit this section of our blog about AC system leaks.

Condensate Pump Failure

If your system has a condensate pump, it will be outside your furnace near its base. For assistance, the pump aids your system in moving water. After condensation rises to a certain level in the pump’s tank, the float switch activates the pump and pushes the water.

Correspondingly, if the pump fails or its tank cracks from age-related wear, it may leak, shutting off your AC. To be sure, look out for pools of water at the base of your indoor unit.

Faulty Water Safety Switches Shut AC Off

In case your indoor AC unit leaks, it may include one or more emergency switches (such as a wet switch or E-Z trap) to shut it down. It may be frustrating to be without cool air in this situation, but it’s worth avoiding potential damage.

In case your indoor AC unit leaks, it may include one or more emergency switches (such as a wet switch or E-Z trap) to shut it down. It may be frustrating to be without cool air in this situation, but it’s worth avoiding potential damage.

However, if one of those switches’ sensors is faulty, it may not shut your system down after a leak. If your AC continues to run under these conditions, irreparable damage could result, creating the need for a very expensive AC repair or replacement! On the other hand, a faulty switch may activate when there’s nothing wrong with your system. Be alert, as one sign of a safety switch problem is your system cycling on and off. 

If you want to learn more about the causes of your air conditioner leaking water, we have an entire blog about it.

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