Why Is My AC Not Blowing Cold Air? 10 Common Causes & Fixes

On a hot day, nothing inspires panic like an AC that doesn’t blow cold air. Even with the best maintenance, there are times when you may need air conditioning repair services. With the right AC maintenance and repairs, you can prevent the underlying problem from becoming worse and enjoy a cooler, more comfortable home.

Overview:

The most common reasons why an AC doesn’t blow cold air are a dirty air filter, incorrect thermostat settings, a frozen evaporator coil, low refrigerant, a dirty condenser coil, a faulty capacitor, leaky or blocked ductwork, blocked return vents, or compressor issues. While some of these problems can be checked by homeowners, electrical and refrigerant repairs should only be dealt with by a professional.

Common Symptoms and Possible Causes

There are several different reasons why an AC might stop blowing cold air. By analyzing the symptoms involved, you can narrow down the potential cause of your problem.

10 Common Reasons Why Your AC Might Not Blow Cold Air 

If your home feels unusually warm, check the vents for cool air. When ACs stop blowing cold air, the following AC repair issues may be at fault. 

1. Low Refrigerant Levels 

When your refrigerant level is low, you may notice the following symptoms: 

• A frozen AC
• Ice around the lines and coils
• Warm air coming from your vents
• Hissing or bubbling noises

If you have low refrigerant levels, you need professional AC repair services in your area. The Environmental Protection Agency (EPA) requires technicians to get a Section 608 certification to recharge refrigerant. Because refrigerants impact the environment and human health, you don’t want to leave this problem untreated.

2. Clogged Drain Pipes

Air conditioners are designed to pull moisture from the air. Then, the excess water is supposed to drain out of your machine using the condensate drain pipe. If this drain gets clogged by dirt and debris, water will stop draining, causing the AC to shut down as a fail-safe measure.

Luckily, this is one of the easiest air conditioner maintenance tasks to perform. You can clean out the drain pipe on your own or call a 24-hour air conditioning repair company to remove the clogs for you.

3. Dirty Filters

Your AC may have more than one filter. You’ll most likely have one filter in your return vent and another in your air handler. If your filters become clogged, it limits airflow and stops your filter from working properly, causing the air conditioner to not blow cold air but run.

How often you need to change or clean the air filters depends on the manufacturer. While 30 days is a common frequency, some air filters don’t need to be changed for 60 or 90 days. 

It’s important to use clean air filters because dirty filters put added strain on your AC. Eventually, this strain can cause your AC to break down prematurely.

4. Power Issues 

If there are any power issues, it could prevent your AC from working correctly. For example, broken wires could prevent the air conditioner from getting enough electricity. 

When you’re dealing with electrical issues, it’s a good idea to shut off your AC until you can get emergency air conditioner repairs. Damaged wires and other electrical problems can be dangerous, so it’s important to leave these tasks to professional HVAC repair services.

5. Blocked Returns

Your air conditioner doesn’t just have vents to release cool air into your home. It also has vents that bring in air, which are known as returns. Normally, returns are placed in a central location in your house so that they can circulate air.

However, you’ll sometimes see multiple vents in a single room. One of these vents may be a return. If the return vent isn’t blowing cold air, it’s because it isn’t supposed to. Returns are designed to bring air in, not out. 

Sometimes, returns can get blocked by furniture, plants, or other items. When this happens, it prevents them from working properly. From time to time, check to see if your returns are blocked in any way. You should also clean the return and the filter inside it regularly.

6. Tripped Circuit Breaker

Don’t be hasty about scheduling a new air conditioner installation. The issue with your AC could be as simple as a tripped circuit breaker, which is easy to fix. 

Typically, air conditioners use an inside and outside breaker. If the outside breaker trips, the vents will still work but will blow warm air. In many cases, fixing a tripped circuit breaker is as easy as flipping a switch. 

However, it’s important to pay attention to how often your AC trips the breaker. If this is a frequent problem, there may be an underlying cause. Faulty compressors, dirty air filters, broken coil fans, and refrigerant leaks can all trip the breaker. In some cases, you may even need to get an air conditioner replacement.

7. Damaged or Clogged Ducts

As you troubleshoot your AC repair needs, check the vents in each room. If some of the vents are able to blow cold air, your air conditioning unit is likely working fine. Instead, you may be dealing with a duct-related issue. 

When your ducts become dirty or clogged, it prevents cold air from getting where it needs to go. Instead of reaching your rooms, the air could be spilling out into your attic or a different space. 

Sometimes, duct-related problems are caused by a lack of pressure. If there’s not enough pressure in the ducts, they won’t be able to move air to your rooms. Issues with your blower fan can also prevent air from reaching distant rooms.

Other than inspecting ducts for clogs, you can troubleshoot duct issues by checking vents to see if air is reaching every one of your rooms. To prevent air leaks and improve your AC efficiency, make sure your ducts are adequately sealed.

8. Dirty Compressor or Evaporator Coils

Your compressor and evaporator coils are integral parts of your AC. Occasionally, you may need to call for air conditioning repair services to fix the coils. Sometimes, the problem is as simple as removing excess dirt, dust, or debris from the coils.

Cleaning Your Compressor Coils

Unlike the evaporator coils, your compressor is located outside your house. The compressor coils are intended to help your AC cool the air. However, the outdoor location means compressor coils can easily become dirty or clogged with plant matter. 

Luckily, you can easily inspect your compressor coils by looking at them. You should never touch them without gloves on because the coil fins are quite sharp. 

If the compressor coils are dirty, you can clean them by turning off the AC’s power. Then, use the water hose to remove dirt, dust, and weeds. An HVAC technician can do a more thorough cleaning during your routine AC maintenance.

Fixing Dirty Evaporator Coils 

Anything that makes it past your air filter can end up clogging your evaporator coils. Before opening any panels to check on them, it’s important to turn off your AC at the breaker box. It’s generally better to leave evaporator coil inspections to the professionals because these coils are situated behind a service panel. 

There are often lines in front of the evaporator coils, and these lines must be dealt with carefully. The fins are especially sharp, so you should wear gloves when working around them. A vacuum cleaner with a soft brush attachment can be used to remove debris and dirt that are near the surface of the coils. For an even cleaner result, an HVAC technician can use a special spray cleaner and brush.

9. Broken Capacitor 

The capacitor is normally responsible for sending a surge of electricity into your air conditioner to start it. These metal cylinders are located under the service panel in your outdoor AC unit. You should never deal with a faulty capacitor on your own. It stores a large amount of electricity, so you’ll get a horrible shock if you touch it. The capacitor must always be discharged before it can be handled in any way.

If you notice any leaks, ruptures, or bulges, your capacitor may need to be replaced. You can normally tell if there is a broken capacitor because you’ll stop receiving cold air. Additionally, you might hear a humming noise or smell something burning. 

When the capacitor is broken, it’s important to call an HVAC company to replace the AC and provide repair services. A broken capacitor is capable of melting plastic and causing damage to other parts, so you need to get it fixed right away.

10. Thermostat Problems

Before you start looking for the best air conditioning installation in your area, it’s important to troubleshoot other issues, like thermostat problems. Your thermostat is responsible for turning your system on and off. If it isn’t working properly, it may stop signaling your AC to turn on when the indoor temperature rises. 

Depending on the thermostat type, you may be able to reset the thermostat or replace its batteries. Then, see if your AC starts blowing cold air again. If it doesn’t, you may need to get your thermostat replaced.

Checklist for Troubleshooting Poor Cooling Performance

Before you call for professional help, there are a few steps you can take to troubleshoot the problem on your own. 

1. Verify Thermostat Settings: First, check the thermostat settings. If the mode is incorrect or the temperature setpoint is too high, the AC won’t turn on to cool your home.
2. Replace or Inspect the Air Filter: A dirty or clogged filter can block airflow into your HVAC system. Ideally, the filter should be changed every 30 to 90 days, depending on usage and the HVAC system’s requirements.
3. Check the Circuit Breaker: If the breaker for the outdoor panel trips, the outdoor unit will stop working and warm air will blow from the vents. Try resetting the breaker once to fix the issue. If it immediately trips again, there’s an underlying problem that must be addressed by a professional.
4. Make Sure All Vents and Return Registers Are Open: Blocked vents can restrict airflow and lead to uneven temperatures in your home. Open your vents and registers. Then, make sure furniture and other items aren’t obstructing the airflow. 
5. Inspect the Outdoor Condenser for Dirt or Debris: Check the outdoor unit for debris. After shutting off the unit at the breaker or disconnect box, you can clean it using a gentle stream of water from your hose.
6. Look for Ice on Refrigerant Lines or Coils: Iced-up lines and coils can happen if the refrigerant levels are low or the evaporator coil is dirty. If there is ice present, you’ll need to schedule professional HVAC services.
7. Listen for Unusual Sounds: Odd noises can indicate the source of the problem, so note any unusual sounds to tell the HVAC technician.

What Not To Do

While homeowners can perform basic maintenance and troubleshooting on their own, the following tasks should be left to the professionals. 

• Don’t Add Refrigerant Yourself: Refrigerant is hazardous to your health and the environment, so only an EPA-certified technician should add refrigerant to a stationary air-conditioning system.
• Don’t Open Electrical Panels or Attempt Any Electrical Repairs: Malfunctioning electrical systems can lead to electric shocks, fires, and damage to your home if they aren’t fixed correctly.
• Don’t Run an AC That Has Frozen Coils: Continuing to run an AC with frozen coils can worsen the ice buildup. The added strain can lead to a burned-out blower motor and compressor failure.
• Don’t Ignore Burning Odors or Unusual Noises: Burning odors can occur because of electrical problems, which can lead to a fire and melted components. Certain noises, such as loud screeching sounds and grinding sounds, can indicate serious motor, bearing, compressor, or other mechanical problems. As soon as you notice burning smells or odd noises, immediately shut off the unit and reach out for professional help.

Why Your AC Runs but Doesn’t Cool

Often, homeowners confuse airflow in their home with cooling. Your blower motor and fan can still circulate air when the outdoor condenser unit is off or not working right. For example, a faulty capacitor or a malfunctioning compressor can lead to a decline in cooling performance. Similarly, low refrigerant levels can lead to warm air blowing through your home despite the fan operating normally.

Smart Thermostat Issues To Watch Out For 

Sometimes, cooling issues are the result of thermostat-related issues. The following are some common reasons why a smart thermostat might negatively impact your home’s cooling performance.

• Incorrect Schedule: When your schedule is set incorrectly, your home may not cool at the time you want it to.
• Eco Mode: Depending on the thermostat, eco mode may use an energy-saving setpoint or range and may reduce cooling when the home is unoccupied. However, both of these features mean your home may be warmer than expected. If eco mode is making your home uncomfortable, you may need to adjust your temperature range so the highest side of the range is lower.
• Wi-Fi Connection Issues: When your smart thermostat won’t connect to Wi-Fi, it won’t receive temperature adjustments from your mobile device.
• Low Batteries: Some thermostats use batteries instead of being hardwired into your home’s electrical system. If the batteries are low, the thermostat may not be able to trigger your AC to turn on.
• Sensor Calibration Problems: Dirty, poorly calibrated, or poorly located sensors may produce an inaccurate temperature reading. As a result, your AC won’t be signaled to turn on. Sensor problems can also occur if the sensor is placed in direct sunlight, near your oven, or in a drafty location. These types of placements can cause it to read a temperature that is significantly different from the rest of the room.

Can Heat Pumps Have Cooling Issues?

Heat pumps rely on the same refrigerant-based technology as air conditioners, so they can absolutely encounter cooling problems. For the most part, heat pumps are susceptible to the same issues as air conditioners. If your heat pump isn’t blowing cold air, one of the following issues may be at fault.

• Reversing Valve Issues: Because they rely on reversing valves to switch the direction of refrigerant flow between the heating and cooling seasons, you may also encounter problems with your reversing valve. If the valve is stuck in heating mode, you’ll notice warm air coming from your indoor vents.
• Refrigerant Leaks: Like ACs, heat pumps can develop refrigerant leaks that can harm cooling performance. 
• Defrost Cycle Confusion: During the defrost cycle, the heat pump temporarily reverses the refrigerant flow during extremely cold weather to heat and defrost the outdoor coils. During defrost, the air from the indoor vents may temporarily feel cooler. As long as the cycles aren’t excessively frequent or extended, the defrost cycle is likely a normal part of your unit’s operation in cold weather.
• Compressor Problems: If a compressor becomes strained by low refrigerant, increased workloads, age, or other issues, it can break down. This can result in poor cooling output, breakers that trip frequently, grinding or screeching sounds, and short cycling.

Any issues with your refrigerant, reversing valve, or compressor should be dealt with by a trained professional. Additionally, you should always call for help if your heat pump stops working during periods of extreme cold or heat.

Common AC Sounds and What They Mean

By noting which sounds occur, you can figure out what is going on with your air conditioning system.

Preventive AC Maintenance Tips

Once you’ve successfully fixed your AC, it’s important to prevent the same cooling problem from happening again. The last thing you want is to require an emergency air conditioner repair on a sweltering hot day. With the following tips, you can keep your air conditioner blowing cool air. 

Seal Air Leaks

To get the most out of your AC, you need to seal any leaks in your ductwork. You should also inspect your home for potential leaks. Windows and doors are common spots where cold air can escape. When this happens, your AC has to work extra hard to keep the air cold. 

Insulate Properly 

You can reduce your electricity bill by improving the insulation in your home. Good insulation prevents cold air from leaving. Other than reducing your power bill, insulation can prevent repairs because your air conditioner won’t have to work as hard to keep your home cold.

Get Routine Maintenance 

Your air conditioner is supposed to get routine maintenance at least once a year. Ideally, this should happen before the summer. During this visit, an HVAC technician will inspect your AC for wear and tear. They’ll clean the AC’s parts, diagnose issues, and recharge the refrigerant. With proper maintenance, you can prevent future breakdowns. 

Change Your Air Filter

If your air conditioner’s not blowing cold air but is running, it may be time to change your air filter and perform routine maintenance. Your air filter should be changed every one to three months to protect your AC.

Clean Evaporator and Condenser Coils

You can protect your AC from wear by cleaning the evaporator and condenser coils. The condenser coils can be cleaned with a hose after the AC has been switched off. Be careful not to bend the delicate fins. While your outdoor coils can be cleaned on your own, the indoor coils should be left to the professionals.

Set a Thermostat Schedule

If you don’t have a smart thermostat, it may be time to invest in one. By creating a schedule for your smart thermostat, you can save energy and reduce the amount of wear on your AC.

Perform Seasonal Checks

To keep your AC functioning at its best, make sure to clean and test your cooling system in the spring before it is used all the time. In the summer, you should monitor its performance and continue completing your routine maintenance tasks. When winter rolls around, prepare your HVAC system for your wintertime heating requirements. As winter begins, make sure your AC’s outdoor unit is protected from the elements.

Homeowner Checklist for Seasonal HVAC Maintenance

• Change the air filter every one to three months.
• Clean the condenser coils. 
• Remove debris from around your outdoor unit.
• Clean the vents.
• Monitor energy bills for signs of sudden jumps in energy consumption.
• Schedule HVAC tune-ups for spring and fall.

When To Call a Professional Immediately

Because of the risks involved, you should immediately call for help if you notice any of the following symptoms.

• A suspected refrigerant leak
• Burning smells
• Recurring ice buildup
• A compressor that won’t start
• Repeated breaker trips
• Loud grinding or buzzing noises
• Cooling problems that remain after basic troubleshooting

Central Oregon Heating, Cooling, Plumbing & Electrical has served Central Oregon homeowners since 1993 and holds a 4.9-star rating from more than 6,800 customer reviews. Our experienced HVAC technicians can safely diagnose and repair refrigerant leaks, compressor issues, wiring problems, and other complex AC issues.

FAQs 

Why is my AC running but not cooling the house?

If you have an AC that is not blowing cold air, a few issues may be going on. You could have a dirty filter, frozen evaporator coils, a faulty thermostat, low refrigerant levels, or blocked condenser coils. You can troubleshoot by resetting your thermostat, changing the air filter, and cleaning the condenser coils. However, if this problem keeps recurring, you should get professional help.

How often should I replace filters?

Ideally, air filters should be replaced every one to three months. You should check with your manufacturer’s directions to see if they have any specifications. Additionally, you should change the filter more frequently if you have a particularly dusty home or are using your AC more frequently.

Can I add refrigerant myself?

No, you can’t. The United States has specific laws about who can handle refrigerants. HVAC technicians are required to be federally certified, so this isn’t something that can be done by a homeowner.

Why does my AC freeze up?

Anything that decreases the airflow or reduces refrigerant levels can cause your AC to freeze. Before troubleshooting, you should let the evaporator coils thaw completely. Then, change your air filter and make sure all of the vents are open. If your AC continues to freeze, you may have a faulty blower motor, dirty evaporator coils, or a similar problem that requires professional AC repair services.

Why is my AC blowing warm air only in one room?

If you have an AC that is not cooling but blowing warm air in one room, it may be related to ductwork issues or closed vents. However, it could also be related to how your system is set up. If the thermostat sensors are in an especially cold area or the room is the farthest from the AC, it may not be getting as cold as the rest of the system. A complete HVAC inspection can help you figure out what’s going on.

How much does AC repair cost on average?

The cost of AC repairs in Oregon depends on the type of issue, the required repair, and the parts involved. While repair costs can vary widely, different components have their own repair or replacement expenses. For example, replacing a circuit board may involve a lower repair cost, while compressor replacement is typically one of the more expensive AC repairs due to the complexity of the component and labor involved. Contact our certified HVAC professionals in Bend to get honest, upfront pricing. 

What’s cheaper long term: repair or replace?

It depends on the type of problems you’re experiencing and the age of your system. If repair costs are less than half the cost of a replacement or the AC is less than 10 years old, it likely makes more sense to simply repair it.

Why does my AC leak water inside?

If your AC is leaking water on the inside, a few things could be going on. There are three essential reasons why this may happen. If low refrigerant levels or a dirty filter cause your evaporator coils to freeze, you may notice water leaking. Clogged condensate drain lines and damaged drain pans can also lead to leaking water.

Can poor insulation cause my AC to seem weak?

Poor home insulation forces your AC to work harder to reach and maintain the same temperature. While it doesn’t actually weaken your AC, it can eventually lead to increased wear and tear. To avoid more frequent repairs and high energy bills, it’s a good idea to improve your home’s insulation.

How do I know my AC is the wrong size for my home?

There are a few signs your AC’s capacity may be too high or too low.

• Short cycling or unusually long cycles
• High humidity 
• Inexplicably high energy bills
• Uneven cooling
• Performance issues

Should I turn my AC off if it isn’t blowing cold air?

Yes, you should turn off your AC to prevent damage to your compressor if you see ice, smell burning, hear serious mechanical noises, or suspect a malfunction. Otherwise, first check the thermostat, filter, vents, and breaker. 

If this issue occurred because of a frozen evaporator coil, you’ll need to wait for your coil to thaw before running the AC again. Additionally, you can troubleshoot by seeing if the breaker has tripped. For repeatedly tripped breakers and recurring frozen coils, you should reach out for professional diagnostics.

Why is my AC cold at night but warm during the day?

This can occur if the daytime heat gain is more than your AC can keep up with. Often, this happens because of an undersized AC unit, a failing capacitor, low refrigerant, restricted airflow, or dirty condenser coils.

Can dirty condenser coils stop my AC from cooling?

The condenser coils are normally responsible for releasing heat into the outdoor air. Excessive dirt buildup acts like insulation and prevents heat from leaving your system. This can cause your unit to overheat and shut down, which will immediately impact your cooling performance.

Why is only one room not getting cold air?

Often, this occurs if there is a ductwork issue, a closed vent, or an unbalanced HVAC system. One room can be unusually warm if it has poor insulation, southern- or western-facing windows, or other issues causing heat gain.

How long should it take for an AC to cool a house?

It depends on the home’s starting temperature. You should feel cold air coming from your vents within minutes, but it will take much longer to cool your home on hot days. In general, ACs can lower the indoor temperature by 2 to 3 degrees per hour. 

Why does my AC keep running without reaching the thermostat setting?

This can occur if your AC is unable to absorb and release enough heat from your home. Clogged air filters, low refrigerant, leaky ducts, and dirty coils are just a few of the issues that could be responsible.

Can a power outage affect my AC’s cooling performance?

Absolutely. Power surges when the electricity turns on again can damage your capacitor and cause increased strain on your compressor. In addition, power outages can reset some of your thermostat settings and trip the breaker on your outdoor unit.

What should I check before calling for AC repair?

Before calling for AC repair, check for incorrect thermostat settings, dirty air filters, and tripped breakers. Then, verify that the vents and returns are open and unobstructed. Note any ice on your evaporator coil or unusual sounds because these can help with the diagnostic process. If basic troubleshooting doesn’t help, you should reach out for professional repairs.

Schedule HVAC Diagnostics Today

As a homeowner, you can troubleshoot by completing the basic checklist. If these steps don’t work, you’ll need to schedule professional repairs to prevent damage to your unit. Timely maintenance and repairs can quickly restore your home’s cooling performance and help you avoid more extensive repairs in the future.

Book your AC repairs with Central Oregon and keep your family cool this summer.