Fixed: Air Only Blows Out Of Defrost And Floor (With Pictures)

Are you having trouble with your vehicle’s AC? Does air only blow out of defrost and floor? Well, this is a problem that many car owners have.

Over time, some of the vents simply stop blowing air. The reason behind this is a small component of the HVAC system that is easy to replace.

In this blog post, I will be talking about why your vehicle blows air only out of defrost and floor and how to fix it.

Key Takeaway

• A Blend Door Actuator is a small electric motor in your vehicle that controls the temperature and airflow within the cabin by adjusting the blend door, which mixes hot and cold air based on the driver’s climate control settings.
• To fix air only blowing out of the defrost and floor, you typically need to check and possibly replace the vacuum lines or the blend door actuator that controls the direction of airflow in your vehicle’s HVAC system.

What Does a Blend Door Actuator Do?

Blend door actuators control the air and temperature blending and the direction of airflow. Blend door actuators have gears that are rotated by a small motor that moves doors in the HVAC incrementally between 90 and 180 degrees to reach desired air and temperature flow.

The blend door actuator is controlled by the vehicle’s climate controls. The blend door actuator can open and close at various positions to block or allow air to pass through the heater core in order to achieve the desired temperature inside the vehicle.

The mode door actuator controls which vent the air blows through. The door on the actuator has two positions: closed and open. The recirculation door actuator allows air inside of the passenger cabin to be recirculated through the A/C system, cooled or heated and recirculated back into the cabin rather than ambient air.

Fixed: Air Only Blows Out Of Defrost And Floor (With Pictures)

• Change the settings on the climate module by switching between defrost, front blowing, etc. The blend door actuator should engage each time you do this and you can actually hear it moving.
• If you do not hear the blend door actuator, it is bad and needs replacing.
• Order a new blend door actuator for your specific make and model.
• Drop down the glove box compartment and locate the blend door actuator.
• Remove the two bolts that are holding it in place.
• Disconnect the wiring harness.
• Install the new blend door actuator.
• Test the defrost and floor.

If air blows out of defrost and floor in your vehicle, there is probably something wrong with the blend door actuator. Here is a very detailed guide on how to test the blend door actuator and fix a vehicle that has air blowing out of defrost and floor only:

1. Required materials for the job

• New blend door actuator
• Cabin air filter
• 5.5-millimeter socket
• Multimeter
• Safety gloves and goggles

2. Diagnose a bad blend door actuator

Before you replace a bad blend door actuator, you will need to diagnose it and make sure it is bad. Each time you try to select the temperature inside the cabin, or to select which vent to blow air, the computer sends a signal to the blend door actuator. The blend door actuator then redirects the airflow to the selected vent with the correct temperature.

So, each time you choose the temperature or the vent, the blend door actuator engages. A bad blend door actuator will actually only allow air to blow out of certain vents. The temperature may also be incorrect.

Also, the best way to actually diagnose a bad blend door actuator is to listen to it. Each time you start your vehicle and turn on the AC, you can hear a squeaking/whining, popping, or clunking noise coming from the dashboard.

3. Order a new blend door actuator

Once you have established that your blend door actuator is bad, it is time to replace it. So, a brand new actuator costs around $30, depending on your make and model. You can either order a new blend door actuator on amazon.com or at your local auto part store. Either way, just make sure that the new blend door actuator is actually compatible with your vehicle.

4. Locate the blend door actuator

The blend door actuator is usually located on the driver’s side, underneath the steering wheel. It might be located in a different spot, depending on your vehicle. So, it is probably best if you check the owner’s manual to see where the blend door actuator is located on your vehicle.

However, as I said, it is probably underneath the steering wheel. It is a little bit hard to reach, so you might need to remove the plastic panel right above the gas pedal and underneath the steering wheel. The key here is to gain as much access as possible in order to remove it.

5. Disconnect the wiring harness connector from the blend door actuator and test it

Before removing the blend door actuator, it is best if you remove the wiring harness connector and test if the current is running through it and powering the blend door actuator. Sometimes the electrical wiring fails and isn’t sending enough power into the blend door actuator.

Turn on your multimeter and set it to 20 DCV. On the bottom left side, there is a green/black port which is always going to be negative, and right next to it there is a yellow/black port which is positive.

Turn the key into an on position and first test the negative connection and then the positive connection. The voltage rating should be between eight and twelve volts on both connections.

6. Remove the faulty blend door actuator

After you successfully diagnose that the wiring is alright, it is time to remove the faulty blend door actuator. The blend door actuator is usually secured in place by 3 bolts size 5.5-millimeters. So, grab a 5.5-millimeter socket and remove the bolts. After you remove the bolts, you will be able to pull out the blend door actuator.

7. Install the new blend door actuator

Install the new blend door actuator and secure it in place with the three bolts that you removed from the faulty actuator. Then, reconnect the wiring. Make sure that you connect it all the way. After the blend door actuator is secured and connected, reinstall any plastic covers that you had to remove in order to gain access.

9. Install the new cabin air filter

A high-quality cabin air filter removes dust, pollen, soot, exhaust fumes, unpleasant odors, and even fine particulate dust from the interior air in the vehicle. It also improves air circulation and prevents dangerous fogging of the windows.

However, the cabin air filter performs another important function. In addition to improving the quality of the air entering the vehicle, the cabin air filter reduces the load on the blower and protects the HVAC system from contamination by keeping dirt, debris, bugs, and leaves out of the evaporator and the heater core.

When the filter element becomes clogged, it restricts the airflow through the heater in the air conditioner. When the air intake is restricted, it’s going to decrease the volume of warm air that the heater can blow into the cabin.

In the summer, it can have the same effect on the air conditioner. That’s not a good situation for the HVAC system because it forces the heater and air conditioner to work harder depending on whether you want warm or cool air. 

Basically, a dirty cabin air filter can restrict airflow to certain vents. Many car owners change their cabin air filters twice a year. However, depending on where you live, you might need to change the cabin air filter more often. It is always a good idea to change the cabin air filter when you replace the blend door actuator just to be safe.

9. Test the AC

At this point, you should be able to change the vents and the temperature of the AC. Before, if your AC blew only on defrost, or on the floor, now, it should blow on all vents, including the dashboard vents. So, start your vehicle and change the AC settings, temperature, and vents.

Why Does My Air Only Work On Defrost?

The AC in your vehicle only works on defrost because the blend door actuator has failed and got stuck into a position where it only allows air to flow on defrost vents.

When you turn on the AC and set the desired vent and temperature, the blend door actuator engages and opens and closes vents accordingly.

However, when a blend door actuator fails and locks up, air will not come out of some vents simply because the gears inside the blend door actuator got broken and will not open and close the vents.

The blend door actuators are designed to last the lifetime of the vehicle. However, most of them break after 70,000 to a 100,000 miles.

The blend door actuator has a board, connector, motor that drives it, a drive gear, transfer gear, and an output shaft. The problem with all blend door actuators comes from the drive gear and transfer gear.

They are made so small with little plastic teeth on them and they need to be moving a big door inside the HVAC case. That tough role, combined with key cycles makes them fail. Basically, if you open up a blend door actuator, the only thing that will be broken is the drive and transfer gear.

FAQs

Q: Why is the air only blowing out of the defrost and floor in my car?

A: There could be several reasons for this issue. One possibility is a faulty blend door actuator, which controls the direction of airflow. Another potential cause could be a broken or disconnected vacuum line that controls the air distribution. Lastly, it is also possible that there is a problem with the HVAC control module. It is recommended to have a professional mechanic diagnose and repair the issue.

Q: Can I fix the problem of air only coming out of the defrost and floor myself?

A: If you have experience working on automotive HVAC systems, you may be able to troubleshoot and fix the issue yourself. However, it is important to note that this issue can be complex, and it is easy to cause further damage if you are not familiar with the specific system in your car. It is generally recommended to seek the assistance of a professional mechanic for proper diagnosis and repair.

Q: How much does it typically cost to repair the problem of air only blowing out of the defrost and floor?

A: The cost of repair can vary depending on the specific cause of the issue and the make and model of your vehicle. On average, the cost of replacing a blend door actuator can range from $150 to $400, including parts and labor. Repairing a vacuum line or an HVAC control module can also vary in cost. It is best to get a personalized quote from a trusted mechanic or repair shop to determine the exact cost for your particular situation.

Q: Can a clogged cabin air filter cause the issue of air only blowing out of the defrost and floor?

A: No, a clogged cabin air filter typically does not cause the specific issue of air only blowing out of the defrost and floor. A clogged cabin air filter can restrict airflow and reduce the effectiveness of the HVAC system, but it does not directly affect the air distribution. However, it is always a good idea to regularly check and replace the cabin air filter to ensure proper airflow and maintain a clean and healthy environment inside the vehicle.

Q: Is it safe to drive with the air only blowing out of the defrost and floor?

A: While it is generally safe to drive with this issue, it can be uncomfortable and inconvenient as it limits your ability to control the direction of airflow. Additionally, if the underlying cause of the problem is a faulty blend door actuator or a defective HVAC control module, there is a possibility that the issue could worsen or other HVAC functions may be affected. It is recommended to have the issue diagnosed and repaired as soon as possible for optimal comfort and functionality.

Q: Can a malfunctioning thermostat cause the problem of air only blowing out of the defrost and floor?

A: No, a malfunctioning thermostat is not directly related to the issue of air only blowing out of the defrost and floor. The thermostat is responsible for regulating the engine’s operating temperature and has no direct influence on the operation of the HVAC system. However, if the engine is running hotter than normal due to a faulty thermostat, it could indirectly affect the HVAC system’s performance.

Q: How can I prevent the issue of air only blowing out of the defrost and floor from happening?

A: Preventing this issue from occurring can be challenging, as it is often due to component failure or mechanical issues. However, regular maintenance of the HVAC system, such as proper cleaning and lubrication of components, can help prevent premature wear and tear.

It is also recommended to promptly address any unusual symptoms or noises coming from the HVAC system to prevent further damage. Regularly checking and replacing the cabin air filter can also contribute to the overall health and performance of the HVAC system.

Q: Can a low refrigerant level cause the issue of air only blowing out of the defrost and floor?

A: Yes, a low refrigerant level can be a contributing factor to the issue of air only blowing out of the defrost and floor. The HVAC system relies on the proper amount of refrigerant to operate correctly. When the refrigerant level is low, it can lead to abnormal system pressure and potentially affect the airflow distribution. If you suspect a low refrigerant level, it is recommended to have the system inspected and recharged by a qualified automotive technician.

Q: What are some other symptoms that can occur along with the issue of air only blowing out of the defrost and floor?

A: Along with the issue of air only blowing out of the defrost and floor, you may also experience other symptoms such as uneven or weak airflow from the vents, a lack of air conditioning or heating functionality, strange noises coming from the HVAC system, or an inoperative climate control system. It is important to take note of any additional symptoms and communicate them to your mechanic for a more accurate diagnosis.

Q: Does the make and model of my vehicle affect the likelihood of encountering the issue of air only blowing out of the defrost and floor?

A: While the issue of air only blowing out of the defrost and floor can occur in any vehicle, some makes and models may have a higher propensity for this problem due to various factors such as design, manufacturing, or common component failures. It is advisable to conduct research or consult with automotive professionals to determine if your specific make and model have a history of this particular issue.

In Conclusion

Air only blowing out of defrost and floor vents in a vehicle can be due to several issues.

The most common cause is a faulty door actuator, specifically the blend door actuator, which controls the direction of the airflow.

When this component fails, it might get stuck in a position that only allows air to blow through the defrost and floor vents.