The main reasons why air only blows through front vents and not the defrost vents or floor vents in your car are a bad actuator, a vacuum leak, and a blown fuse.
Keep reading this article to find out more about these issues in detail that keep your HVAC system from functioning properly and learn how you can fix them. We’ll also discuss some of the common reasons why air only blows through defrost vents and how you can fix them. Let’s dive in!
Table of Contents
Air Only Blows Through Front Vents [3 Easy Fixes]
The most common reasons why air only blows through the front vehicles in your vehicle even when you select floor or defrost vents are:
1. Bad Actuator
There are many actuators in your car that control the flow of air. They open and close to a certain extent to make sure that you get your vehicle to the desired temperature. These door actuators are typically located by the dashboard on the passenger side of the car.
But these actuators can wear out with time and get stuck. When the door actuators that control the other vents except the front vents get stuck, you won’t have any air blowing through them.
There are also different actuators that control the flow of cold and hot air. If you’re only getting cold air from the different vents, that means the actuator that controls the hot air has gone bad and vice versa.
Solution:
If you’re getting only hot or cold air through the defrost vents or floor vents, you only have actuators of one kind going bad. Replacing them will solve the problem. But if there is absolutely no airflow to the other vents, you’d need to replace both kinds of actuators.
The most common actuators that go bad are the blend door actuators. Follow these steps to replace them:
- Remove the HVAC CTRL fuse.
- Open the instrument panel by pressing the tabs that support the stop bumpers.
- Remove the wiring harness connected to the actuator.
- Unscrew the blend door actuator screws.
- Take out the old actuator and put the new one in its place.
Do the steps in reverse to seal the new blend door actuator in its place. Once the new actuator is installed, you need to recalibrate it. Follow the instructions that come with the actuator so that you can successfully calibrate it.
As a general rule, you can take any one of the HVAC fuses in your car for a few minutes, then install and turn the key on for a few minutes again so that the ECU can forget the old settings and calibrate the new actuator.
Many people mess up the installation of the actuators and never end up solving their problem. Test your actuators with a voltmeter and listen for it making a clicking noise to make sure it’s working. If you don’t feel comfortable replacing it yourself, hire a mechanic to do this job.
2. Vacuum Leak
Actuators are primarily of two types – vacuum and electric. The vacuum actuators go bad when there are leaks in the system. Any vacuum leak in the system can keep the air from coming through the defrost or floor vents. Losing the vacuum supply to the control head defaults to defrost.
Locate the small black vacuum line that passes through the passenger side of the heater core. It should go to a canister and end up in the intake manifold. If it’s broken or disconnected, that means you have a vacuum leak in your car.
Solution:
Once you’re able to identify where the leak is coming from, you can fix it by sealing it. If you’re having trouble locating the leak, hire an expert mechanic to locate and take the necessary steps to seal the leak for you.
3. Blown Fuse
Electric actuators get their power from the battery and they have their own fuse. If the fuse is blown, the electric actuators won’t work properly and cause the air to only blow through the front vents.
Check whether the actuator fuses in your car are blown. If you’re wondering why is one of my vents not blowing air, a blown actuator fuse could potentially be the reason behind it. While you’re at it, also check the other fuses of your HVAC system and make sure that they’re working well.
Solution:
Replace the blown actuator fuse with a new one. If any of the other HVAC fuses are blown, replace them too to get your HVAC system working properly. If the problem persists even after replacing the fuse, you may have to replace the actuator itself to have the air blow through all the vents.
Why Air Only Blows Through Defrost Vents
Just like the air only blowing through the front vents is a problem for your car, another major problem faced by many car owners is that the air only blows through the defrost vents.
You’ll notice the front vents not blowing air when it happens. The reasons why air only blows through the front vents also hold true for air only blowing through defrost vents.
A bad motor actuator, vacuum leak, or blown fuses in the HVAC system can lead to air blowing only from the defrost vents. But here are some additional reasons that can cause the air to only blow through the defrost vents:
i). Obstructed Air Intake
If you’re wondering why aren’t my vents blowing air except the defrost vents, obstructed air intake could be the main reason behind it. The air enters your vehicle in two main ways – the vents above the dash and the duct where the air is recirculated.
If one or both of these lines are blocked in any way, the AC can remain stuck on defrost and you’ll find air not blowing through the front vents in the car. The most common reason why the air intake gets obstructed is because of the build-up of dirt and debris in them when you drive your car.
Things like fallen leaves, sticks, tree nuts, branches, or birds nest accumulate in the air intake vents and create a blockage. This blockage traps the air inside the vehicle and also fails to intake more air from the environment.
Solution:
You need to deal with an obstructed air intake problem as soon as possible to prevent your car from growing mold. You can prepare many homemade solutions and use them to clean the air intake in your car instead of going to the mechanic and losing your money.
One of the easiest methods is to use white vinegar and a warm water solution to clean the vents. Add the two in equal proportions and dip a foam paintbrush in the solution.
Rub it on the vents and clean them. You can also use a duster or toothpick to take out the solid materials clogging the air intake of your car.
ii). Faulty Blower Motor
Another reason that can get the AC stuck on defrost and leave you wondering why air only blows through defrost vents not front vents in my car is a faulty blower motor. The blower motor blows air through the vents and the flow of air coming from it is controlled by a blower resistor.
When the blower motor fails to function properly, it cannot exhaust the air through the vents and that will lead to losing the balance of the airflow inside the cabin. Luckily, a faulty blower motor is easy to diagnose.
You’ll hear a loud humming noise or an unusual vibration coming from the AC system when the blower motor malfunctions. You may also notice a burning smell coming from the air vents due to overheating when the blower motor fails to keep the temperature under control.
The blower motor also usually makes a noticeable sound when it’s operational. The sound of the blower motor itself will dissipate when it goes bad.
Solution:
If you’ve successfully identified that you have a faulty blower motor, you need to replace it. We recommend hiring a mechanic to do this job as it can be a tricky job to replace the blower motor.
Apart from the reasons mentioned, there are many other reasons that can cause issues in the HVAC system of your car. Check out our detailed guide on dashboard air vents not working if you want to learn more about this issue.
FAQs:
Why are my vents blowing hot air?
There are actuators in your car that control whether you’ll get hot or cold air in your car based on the temperature settings. When these actuators go bad, you can only get hot or cold air coming through the vents.
Why AC only blows through floor vents?
The main reasons why an AC only blows through the floor vents and not the dash vents are a bad blend door actuator, vacuum leak, blown fuses, and faulty relays.
How do you access the car vents?
There’s a device called the thumbwheel which is commonly used to open and close the vents in your car. Wheeling it to the right opens the vents and wheeling it to the left closes them.
Why are my front vents not blowing air?
Clogged air intake, bad actuators, blown HVAC fuses, faulty blower motor, and malfunctioning blower resistor are the most common reasons behind no air blowing from the front vents in your car.
Conclusion
It can be extremely frustrating when you find out that air only blows through front vents and not through the other vents. But now you the main reasons behind it and how you can diagnose and fix each of these issues.
Hopefully, you’ll be able to pinpoint the exact issue that causes air to only blow through the front vents in your car and how you can fix it after completing this article. Drop a comment below if you have any more questions about the HVAC system of your car.
About John M
John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.