Why Is My Central AC Running But Not Blowing Air?

It’s that time of the year; the heatwave is on your neck. You can’t do anything but feel disappointed with your central AC running but not blowing air.

If your central AC is running but not blowing air, your unit’s fan capacitor is bad or experiencing failure. When working properly, the capacitor sends an energy surge to your AC’s outdoor and indoor fan motors and compressor running, helping blow cold air into the room. Clogged filters, dirty condensers, frozen evaporator coil, and faulty thermostats can also cause problems.

These are some of the things you can check when you experience this issue but there are several other things you can look at as well.

So, in this article, we dive deep into what’s causing your central AC not to blow cold air and DIY steps you can take to deal with the problem.

Reasons your Central AC is Running but not Blowing Cold Air

Power Problems with your Air Conditioner

When extra hot weather strikes, most homeowners crack up their central air conditioning unit 24/7, straining their power grid. Power outages happen during heatwaves.

If a power outage occurs, the clock/timed settings on the central air conditioning unit’s thermostat may have changed; you’ll have to reset it.

Thermostat Issue

The AC’s thermostat could have some problems, or you have drained its batteries. Hence, it won’t transport enough signals to the central air conditioning unit.

Because of the insufficient signal transmission, your air conditioning unit won’t blow cold air or dispel warm air.

Clogged Filters

If contaminants clog the air filter on your AC system, cool air and heat energy will have a rough time passing through them.

A clogged air filter causes an evaporator coil to freeze, causing your cooling system to work harder for a lengthy period.

Vents and Registers are not Blocked

Often, we never mind where we place the vents and registers when moving furniture within our homes.

For example, if you set a sofa in front of vents, you will block them. As a result, you will interfere with indoor and outdoor air quality.

Dirty Condenser Unit

An air handler that isn’t supplying conditioned air can arise from an outdoor condenser system being dirty.

The condenser system, which you can find in the outdoor unit, is prone to soot, dirt, tree branches, leaves, debris, twigs, and other airborne particles. The mentioned above materials may clog the outdoor systems.

AC not Blowing? It could be Ductwork or Other System Design Flaws

Too many bends across the ductwork or improper space designs can lessen the airflow of air conditioners. Such alterations or methods render your original ductwork useless or irrelevant.

Leaks and Blockages

Again, it’s your ductwork. If it leaks through cracks and holes, the indoor air won’t make it to where you need it the most. In your work and residency space.

Soiled Evaporator Coil

If the evaporator coil cakes in grime, it won’t release or absorb heat energy via the heat pump. Hence, the evaporator coil will work extra hard to boost your indoor air quality.

AC not blowing? Maybe the Fan is not Running

A condenser fan pushes air across the vents of AC units. If dust or dirt covers the blower fans, their blades will stop blowing air, which hampers airflow. A faulty blower motor can’t do its role in pushing.

Damaged Heat Pump

If the heat pump system won’t cool, check the temperature settings on your air handler. Examine the air filter, condenser system, and thermostat settings for earlier l problems that I described. Phone an HVAC professional if everything ticks out and you’re still uneasy.

Frozen Evaporator Coil

An indoor evaporator coil in cooling systems works when it soaks up heat from the surroundings. The evaporator coil freezes up if there is insufficient heat to soak up.

The frozen evaporator coil leads to poor airflow. And if the airflow is poor, it brings about issues in the air filter, blower fan, or ductwork.

Undersized AC Unit

In moderate conditions, one may not notice any problems with an undersized system. But, when temperatures increase outdoors, your air handler may operate over time while struggling to provide cool air in your home’s indoor part.

Broken AC Fan Motor in the Condenser Unit

When the condenser fan doesn’t power on/off, or its blades are swerving, the cause may be dirt in the unit’s cabinet. The land on the cabinet may clog the air filter or overheat the air conditioner.

Also, it could be a case of wear and tear overworking both the indoor and outdoor units.

Improper Installation Causing Air Duct Leaks

An air conditioner running despite someone installing it wrongly leads to leaky air ducts. The situation means that your air conditioner could blow cold air towards a crawl space that you never planned to cool, leaving out the other rooms.

Bad/Dirty Compressor

A compressor found in an air conditioner may stop functioning if mineral deposits or dirt buildup on the indoor evaporator coil.

Also, the compressor may break down because of clogged suction lines, incorrect oil lubricant levels, electrical burn, or refrigerant leaks.

How to prevent problems like your AC not blowing cold air

Cleaning an HVAC system is a straightforward way of keeping it in a sufficient condition and insulating it from wear and tear. If you’re doubtful of the step to take, give an HVAC pro a call or follow these DIY steps of cleaning an air handler:

1. Begin with the air-con air filter – unfortunately, you can’t clean up all dirty air filters using a vacuum and water. But for the ones you can clean, do it each month or replace them too.

2. Examine the evaporator coil – examine the evaporator coil housed in the air handler for signs of the flaw if you own a central/window AC unit. Remember to straighten any bent evaporator coil fins using a fin comb. And to improve performance, you can also use a vacuum hose to clean up the AC’s coil fins.

3. Inspect your home’s window seals – holes or cracks in the enclosure. Part of your window AC system lets cold air out, causing the windows to exhaust energy. In case of damages to the units, call an HVAC pro for help or try to shut the air leaks on your own.

4. Clear the air handler drain line – often, the drain line on the new system running can clog up with debris, which causes water buildup. To clear out the clogs from the drain channels, you need to use a plumber’s snake, distilled vinegar, or stiff wire. 

5. Check for debris – if your home has a split-system unit, part of its maintenance should include clearing out leaves and debris from the fan, condenser, and compressor. You will also need to trim plants near the condenser; this prevents your drain channels from clogging up even more.

What to do if your AC Unit is not Cooling your Home

1. Check the temperature setting on the air-con thermostat – It may sound simple. Still, when a condensing unit is running but not blowing cold air, it’s simply a matter of turning the thermostat temperature setting to “Fan” from “Automatic.” Also, examine the circuit breaker or breaker box to see if they work correctly.

Easy fix – examine and reset the thermostat’s switch. The switch should read “Fan” instead of “Automatic.”

2. Replace dirty filters – discard and clean the return-air filter. If you can’t see through the filter, replace it. If your system can supply conditioned air and see through the filter, examine the other air-con parts.

3. Unclog the HVAC unit’s condensation drain – track down the edge of the indoor portion (utility room) of the condensation drain line. After that, visually examine it for clogs. If you discover clogs, carefully clear the drain line using the edge of a screwdriver or any other narrow item. After wiping out algae/mold clogs, pour the vinegar through the condensation pan. The pan sits beneath evaporator coils within the blower unit. Vinegar prevents future clogs and kills residual mold buildup.

4. Diagnose duct malfunctions – If you own an unfinished basement, examine your ductwork for any loose joint. Refit the joint’s edges and tape the new joint securely using duct tape if the joint is loose. If a ductwork joint becomes loose within a wall, you can’t uncover it; hence you’ll need to contact an HVAC pro.

5. Clear up the compressor’s surrounding areas – If leaves or debris pile near the compressor unit, it will pull out insufficient air. Locate the compressor in the outdoor condensing unit to determine if it has leaves or debris near it.

Easy fix: clear out debris or anything crowding it. For example, overgrown vines, grass, or weeds. For maximum performance, but nothing near the compressor unit.

6. Clean dirty coils – if your unit is operating but not blowing cold air, check the filters. Typical AC units have two coils;

  • Condenser coils in the outdoor compressor unit
  • Evaporator coils within the indoor blower unit

When debris and mold cover the set of coils, cold air input suffers. To clean them, discard the metal casings protecting them.  

Easy fix: if you’re unsure of opening the unit, pass it to an HVAC pro instead.

Know When To Call a Professional HVAC Contractor

If you have gone through the DIY steps above and your indoor unit is 10+ years old, blame a refrigerant leak, blocked supply vents, frost formation, jammed supply vent, or a faulty compressor.

By law, a licensed HVAC pro is the sole person who can handle Freon. If you experience system shutdown or low refrigerant levels in a 10+-year-old unit, you’ll have to get a new cooling system. Look for an HVAC pro for further information.

Why Is My Central AC Running But Not Blowing Air FAQs

Why Is There No Air Coming Out of My Vents?

When dust, hair, and debris jam the system’s filters, they reduce its airflow in the vents. The airflow reduction decreases your HVAC unit’s efficiency. In addition, furniture blockage can cause the vents not to blow cold air.

What Is It When the Outside Ac Unit Is Running, but the Inside Is Not?

A jammed condenser unit can cause your system without dropping indoor temperatures. A condenser fan dispels air to the outdoor unit via the condenser coil, taking out heat energy from your house.

How Do You Clean a Clogged Condenser Coil?

1. Visually inspect your AC 

2. Remove debris using a brush attachment 

3. Uncurl the coil fins using a fin comb

4. Wet and coat the coils using a coil cleaner

5. Use water to rinse the remaining coil cleaner

How do I reset my AC compressor?

1. Power down your air-con

2. Find the button

3. Hold the compressor’s reset button and release it after 3-5 seconds 

4. Restore your HVAC’s power

Does Central AC Bring in Outside Air?

No, a central AC system doesn’t dispel air outside your home. Instead, the units soak up heat/humidity from your home’s air, and later on, they release cool air via the duct system. 

What Are the Components of a Central Air Conditioning System?

  • Outdoor units contain; condenser coils, electrical components, a fan, and a compressor.
  • The evaporator coil lies on the gas furnace indoors.
  • Refrigeration lines or a string of pipes that connects the indoor and outdoor equipment.

How do I Know if My AC is Failing?

When your central air system isn’t working properly, you will notice inadequate cold air flowing across the vents. Sometimes, the air supply isn’t cold. When such a malfunction happens, the chances are that your unit is low on refrigerant or its compressor is failing.

What is the Common Air Failure on an Air Conditioning System?

Frozen Evaporator Coil

Insufficient air leads to an evaporator coil freezing up. The frozen coil can stop your air-con from operating by freezing it up. Jammed ducts/vents, a faulty pan, and dirty filters reduce your system’s airflow. 

What Happens When AC Fails?

Weak Airflow

If the unit’s compressor fails, your system won’t have sufficient power to push the air. Unfortunately, it’s expensive to repair or replace your HVAC’s compressor.

Should I Turn off the AC if it’s not Cooling?

If your HVAC isn’t blowing cool air, shut it down and call your preferred HVAC pro to help you out. I always tell homeowners to turn off a unit that isn’t cooling properly.


We’ve seen how a simple thermostat setting can correct your AC’s blowing problem in the article. So, do you regularly check your AC’s basic parts for faults or clogs? If yes, what part can you fix without extra effort? And if not, are you scared of tearing your AC apart?

If the AC parts are scary to discard, this article will guide you through the DIY steps you need. Just do it! But call an HVAC pro if the issue isn’t a minor one.