9 Reasons Your Air Conditioner Isn’t Blowing Cold Air

When the weather starts to warm up, you want your central air conditioning to be up to par to cool your home during the hottest days. There’s nothing more exasperating than turning on your aircon on a scorching summer day and realizing it’s not blowing cold air. So, what causes this problem, and how can one fix it, you may ask?

The most common reasons for an air conditioner not blowing cold air are power problems, wrong thermostat settings, and dirty filters. It could also be due to frost buildup, a faulty fan/fan motor, a blocked drain line, low refrigerant levels, dirty condenser coils, or leaky ducts. 

Luckily, most of these issues can be resolved quickly, either with a DIY fix or with a professional’s help. In this post, therefore, I will:

• Discuss the possible causes of an air conditioner not blowing cold air.
• Share some troubleshooting tips that you can try yourself to get the unit up and running again.
• Tell you when to call an A/C technician.

Power Problems

The first thing you need to do if your air conditioner isn’t blowing cold air is to check if the unit itself is getting power. If it’s not plugged correctly into the outlet, there will be no voltage to run the internal components responsible for cooling air. The hot indoor air won’t even be sucked into the system, to begin with, so in other words, your aircon is just dead.

How to Fix

If the power cable is still intact, check to see if you have any tripped circuit breakers. Air conditioning systems usually have two breakers; one for the inside unit and another for the outside unit. If one of these breakers trips, no cooling will take place. 

To reset a tripped circuit breaker, flip the dropped switch back to the ON position. If the switch drops again immediately, contact your HVAC guy right away, as there could be a more complex problem with your AC. 

Thermostat Issues

Still not getting cold air from your AC? Check the thermostat; maybe someone accidentally changed the settings, or it has malfunctioned. 

Your thermostat communicates with your air conditioning unit and tells it when to initiate the cooling cycle. If it’s not set correctly, it won’t send accurate signals to the system, and the cooling process won’t start.

How to Fix

Check whether the fan is set to ON and change it to AUTO. When the fan is ON, your AC runs continuously, irrespective of whether it’s making the air cold or not. The AUTO position ensures your fan kicks on only when the system is cooling the air. 

If this doesn’t work, try dialing down the temperature about 10° lower than the current thermostat reading and see if that triggers the unit to produce cold air.

Make sure your thermostat batteries aren’t dead too. Even almost-dead batteries can cause the device to send inaccurate information to the cooling unit and result in the system not producing cold air. Replace such batteries and wait to see if it solves the problem.

Sometimes, the thermostat may be completely unresponsive, and the display won’t come on even after replacing the batteries. In such instances, it’s best to work with an AC expert. A professional will let you know if the thermostat needs a broken wire fixed or if the entire device needs replacing. 

Clogged Air Filter

Another common cause for home cooling systems not producing cold air is a dirty filter. So, if your unit is getting electricity and communicating effectively with the thermostat but still acting up, your filter is the next thing you should check. 

Your AC filter’s work is to remove dust, dirt, hair, and other debris from the air that enters the system from your home. Normally, a fan draws hot air from your indoor space into the cooling elements, and then the air is blown back into the room. 

Over time, dirt can clog the filter, restricting airflow into the system. As a result, the air being cooled becomes too little, meaning the air being blown out of the unit is also very little. You may think your AC isn’t blowing cold air, but in the real sense, the air coming out of the vents is just too little to make any difference. 

How to Fix

If you have a dirty filter, change it and get in the habit of replacing it every 30 days. Also, if your filter is so dirty that you can’t even see the other side, there is a good chance some of that dirt has found its way into the evaporator coils and other internal components. In this case, it would be wise to call in an HVAC expert to assess your system. 

Ice Buildup

Mostly, ice buildup results from insufficient airflow or an incorrect amount of refrigerant. Suppose your system is not getting enough air or the refrigerant levels are too low. In that case, the temperatures near the evaporator coils will drop below the freezing point, and the nearby water vapor will condense onto the coils. 

If the problem is not identified and addressed early enough, the ice buildup will continue until the entire air conditioner is covered in ice. This will prevent the coils from effectively absorbing latent heat from the warm air drawn from your home, and in the end, your AC will not be able to produce any cold air. 

To know if ice buildup is why your AC is not blowing cold air, look for spilled water from melting ice on the floor near the indoor or outdoor unit. Sometimes this ice won’t melt and will be left hanging on the outside of the unit. 

How to Fix

The first thing you need to do when you find ice on your AC is to power off the unit and wait for the ice to thaw. You can hasten the process with a hair drier or heat gun. Don’t use any sharp object to scrape the ice off, as this could easily damage your evaporator coils. Afterward, check to see whether your filter is dirty and change it.

If you have finished melting the ice and replacing a dirty filter and your air conditioner is still not giving you cold air, low refrigerant levels could be blamed. Have these levels examined by a professional? Depending on the circumstances, they may decide to raise the refrigerant’s levels and repair other components that could lead to an ice buildup like a dirty air blower or a faulty expansion valve. 

Faulty Fan/Fan Motor

Your home cooling system comes with both an indoor fan and an outdoor fan. The indoor fan blows hot air over the evaporator coils to cool them, and the outdoor fan blows air over the condensing unit to remove heat from the AC. 

If one of these fans isn’t working correctly, perhaps due to a defective motor, worn belts, lack of lubrication, or clogging, there will be restricted airflow. 

So, how do you know your blower fan is faulty?

Well, for starters, if your air conditioner is not blowing cold air, you should already start suspecting your fan, especially if you have tried all the other fixes discussed above. It could be that the fan is rotating very slowly and generating weak airflow. Check whether your AC offers fan speed settings and set the speed to high. If that doesn’t fix the problem, check to see whether the motor bearings need oiling. 

Another sign that your fan is faulty is a buzzing noise. If you hear loud rattling when you turn the AC on, there may be loose blades hitting the side of the unit. Check to see if a blade is stuck in the condensing unit. If nothing is stuck there and the blades seem to be moving freely and smoothly, then the noise could be from a dying fan motor. 

How to Fix

No matter what’s causing your fan to blow insufficient air, fan problems must be addressed quickly because if not, the reduced airflow can cause the compressor to malfunction, and your air conditioner will be as good as dead. There are some simple fixes you can try yourself, like adjusting fan speed settings. But advanced fixes like oiling motor bearings and putting loose blades back into place will be best left to professionals. 

Blocked Drain Line

A drain line is an exit route for the moisture absorbed from the hot air as it passes over the evaporator coils. The coils convert this moisture into the water, which is collected in the condensate pan. This water is then passed through the drain line and dropped outside near the outdoor unit. 

As air circulates through the cooling system, dirt, dust, and other objects can be trapped by moisture. This is especially true if you haven’t changed your air filter for some time. The buildup from your filter can be transported as condensate to the drain lines, and over time it can be trapped inside the drain lines, causing a blockage.  

When this happens, the condensate pan overflows, and slowly by slowly, this water starts flooding the system. But air conditioning units come with a water safety switch, so when the system begins to flood, the switch automatically triggers it to shut down to prevent damage, and no further cooling takes place. Every time you turn on the AC after this, the safety switch will turn it off prematurely, making you think the system isn’t producing cold air. 

One of the most common signs of a clogged drain line will be the unit’s failure to produce cold air. You may also notice water flooding near the air handler unit and a moldy smell coming from the vents. 

How to Fix

You can unclog blocked drain lines by simply flushing them with a vinegar solution. If the water doesn’t flow normally after cleaning the pipe, the blockage is probably too big for a DIY fix; have it checked by an HVAC tech. 

Note: AC condensate drains should be cleaned every month or as often as you change your air filter. This will help you stay on top of any clog and prevent complex problems that may affect your unit’s proper functioning. 

Low Refrigerant Levels

A refrigerant is a mix of chemicals that flows through the evaporator and condenser coils to remove heat from your air conditioning unit. The refrigerant quantity in a cooling unit is referred to as charge and doesn’t evaporate or dissipate during a normal operation.

However, due to damages or poor maintenance, a refrigerant can sometimes leak, bringing down the charge of your AC. With the reduced charge, there’s reduced heat absorption. The evaporator and condenser coils remain cold, causing the air’s moisture to freeze around the coils. This kind of buildup prevents the coils from exchanging heat effectively, which results in less cold air blowing into your home. 

A low refrigerant charge could also cause damage to the compressor, and continued use of your air conditioner in this state can cause it to overheat or burn out. You don’t want it to come to this because you will have to install a new compressor for your unit to function again – and compressors aren’t cheap!

There’s no way to know for sure you have low refrigerant levels unless with the help of a licensed HVAC technician. But certain signs could point you in that direction, like your air conditioner not producing cold air, ice buildup, long cooling cycles, and higher energy bills. 

How to Fix

Locating and sealing a refrigerant leak can get your unit producing cold air again, but this task should be left to a professional. They will also recharge the refrigerant with the right blend and amounts of chemicals. 

Dirty Condenser Coils

Condenser coils are installed in the outside unit of your air conditioner. Their work is to remove heat from the refrigerant, a compound responsible for transporting warm air from the inside of your house to the outside. The outdoor unit blows air over the coils, transferring the heat from the refrigerant to the outside air. This effectively gets rid of heat from your house. 

Since condenser coils are positioned outside your home, they are constantly exposed to dirt, dust, leaves, debris, and other objects from the outdoor environment. Over time, dirt builds up on these coils, creating a layer that prevents air from being blown effectively over the refrigerant flowing inside of them. 

As a result, heat is not adequately transferred from the refrigerant to the outside. This means that the refrigerant will not be cool enough to absorb as much heat as possible from the warm air absorbed from your home; hence the unit will also not produce cold air. 

Not just that. With the deposited layer making it difficult for the cooling system to perform its duty, the unit will be working harder to compensate. This will get it using more electricity than usual, which means your cooling bills will also go significantly higher. There is also a higher risk of the air conditioner breaking down because it works harder/longer than it’s designed to. 

How to Fix

If your air conditioner isn’t blowing cold air and you have been paying crazy electricity bills for the last couple of months, your condenser coils are likely the culprit. Remove the coils and give them some good cleaning. Depending on the dirt level, you can use compressed air, a brush, a commercial cleaner, or a mild detergent and water. 

If your condenser coils are heavily clogged, you may need to go for heavy-duty cleaning, and this may also mean you will require to remove some parts of your AC unit. In such instances, it would be best to let a professional do the job for you. 

Leaky Ducts 

The duct system is used to carry cool air into your home. If it’s damaged, the conditioned air will escape through the ducts, and only a small amount of it will reach the vents, making it appear as though the air conditioner isn’t blowing cool air. 

Leaky ducts make your home less efficient in two ways. First, the air conditioning unit wastes energy on providing cold air that never reaches the desired areas. Second, the unit works harder to maintain the home temperature at your preferred levels, significantly increasing your energy bills. 

How to Fix

The best way to find out if the problem with your air conditioning is caused by leaking ducts is to check if some rooms or spots in your house are colder than others. If you can find the leak, then you can go ahead and seal it yourself. 

While you can seal leaks yourself, some of the ductwork can be in areas that are difficult to reach. In that case, you will require an expert to locate and close up the leaks. 

Final Thoughts

The last thing you want when summer sets in is an air conditioner that won’t blow cold air. If you are experiencing this problem with yours, you should:

• Check to see the unit has power and the thermostat is set right.
• Replace dirty air filters.
• Have an expert inspect your fan motor, condenser coils, drain lines, and ductwork.

Fresno Air Conditioning Repair: Fresno Air Conditioning Repair offers air conditioning repairs and free estimates on new installations.

Steve Rajeckas

Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he’s not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.