Here, we\u2019ll go over these problems and discuss which components may be at risk. Furthermore, you\u2019ll be able to troubleshoot your vehicle and take the necessary steps to fix it once you\u2019re done with this article. <\/p>\n\n\n\n The issues that cause air to blow through the defrost vents only are as follows:<\/p>\n\n\n\n The mode door actuator plays the crucial role of determining which vents the air will flow out of in a car\u2019s air conditioning system. However, these are electronic components that can wear out over time and become dysfunctional. <\/p>\n\n\n\n It usually comes with strips and components made of plastic that can get damaged over time. Apart from that, excessive load, inappropriate wiring, etc. can lead to a malfunction. <\/p>\n\n\n\n Another way of knowing if the mode is broken or not is, you need to listen for a clicking noise when the AC is on. If there is one, then you can be certain that there\u2019s an issue with the mode. <\/p>\n\n\n\n The blend door actuator\u2019s main purpose is to allow or block the air passing through the heating core. This way, it can regulate the temperature of your vehicle\u2019s system. <\/p>\n\n\n\n However, this component is usually made of plastic and can wear out after years of use. Also, if the electric motor burns out for some reason, this component can stop working altogether. <\/p>\n\n\n\n When this component is damaged, you\u2019re likely to hear a ticking sound from the dash. <\/p>\n\n\n\n Blend door actuators can be replaced at a very reasonable price. So, if you\u2019re facing this issue, you can buy an aftermarket actuator and replace it yourself, or consult a professional. <\/p>\n\n\n\n The blower motor works with the blower resistor to control the flow of air that\u2019s being pushed through the vents. If the blower motor is damaged, it fails to push any air down the vents, so you may get air blowing through the defrost vents only. <\/p>\n\n\n\n The Blower motor is usually damaged from years of wear and tear. Usually, these get damaged when they get overheated due to airflow restrictions. In other cases, they can get rusty, which can make them brittle. <\/p>\n\n\n\n You can detect if the blower motor is damaged or not through two symptoms. Firstly, look out for a vibrating or screeching noise. Secondly, you may smell something burning if the blower motor is overheating. <\/p>\n\n\n\n If the blower motor is just rusty but the components are working fine, you can get it cleaned of rust professionally. You can also attempt to clean it at home with a rust dissolver. <\/p>\n\n\n\n However, if the component itself is broken, then you\u2019ll have to replace it or replace the affected part of the component. <\/p>\n\n\n\n As discussed, the blower resistor and blower motor work in cohesion. The function of the blower resistor is to push the air through the dashboard vents into the vehicle. <\/p>\n\n\n\n Also, the resistor helps determine the amount of airflow into the system. Simply put, it lets you select different fan speeds for the AC. <\/p>\n\n\n\n However, certain issues can lead to a blower resistor failure. It\u2019s commonly damaged due to thermal overload. You can check whether the blower resistor is broken by checking the fan settings. <\/p>\n\n\n\n If the airflow doesn\u2019t change regardless of how much you change the fan settings, you\u2019ll need to replace the blower resistor. <\/p>\n\n\n\n The electrical relay helps continue the entire ventilation system of your vehicle. If some part of the electrical relay gets damaged, then the system will fail to ensure optimum airflow. <\/p>\n\n\n\n This is also when the air coming into the vehicle will have sufficient momentum to flow by itself, as no external factor will control where the air will flow through. <\/p>\n\n\n\n So, depending on the structure of the ventilation system, the air may blow only through the defrost vents. <\/p>\n\n\n\n This can be the most complicated issue to fix, as the electrical wiring can go wrong at many different places. We highly recommend visiting a professional for getting this sort of problem fixed. <\/p>\n\n\n\n The purpose of the fuse is to regulate the voltage in the ventilation system so different electric component is supplied with the appropriate amount of power. <\/p>\n\n\n\n However, the fuse might blow under pressure, which will halt the ventilation system. <\/p>\n\n\n\n When the ventilation system stops working, the air might force itself through the defrost vents only. <\/p>\n\n\n\n In this case, you\u2019ll need to check the fan breaker, ventilation breaker, and clutch breaker. If any or multiple of these components are damaged, then you\u2019ll need to fix these to restore your vehicle\u2019s ventilation system to proper. <\/p>\n\n\n\n A lot of vehicles made between 1990 to 2005 come equipped with vacuum-operated vents. In this system, there\u2019s usually a vacuum tank that\u2019s connected to the vent doors with hoses. <\/p>\n\n\n By default, the doors are set to the defrost position. When the user makes any changes to the vent knob, he is changing the position of the vents as necessary. <\/p>\n\n\n\n However, if any of the vacuum lines break, the entire system collapses as there\u2019s no vacuum holding the vents in position. Thus, all the vents return to their default position, which is the defrost vent. <\/p>\n\n\n\n This leads to air blowing in through defrost vents only. To fix this, one can either get service from a professional, which will cost a fair bit. <\/p>\n\n\n\n If you want to fix it yourself, you\u2019ll need to detect the vacuum leak first. <\/p>\n\n\n\n You can use a smoke machine to detect if any of the hoses are leaking smoke or not. Once you determine which line is leaking the smoke, you can get it replaced to solve the problem. <\/p>\n\n\n\n In certain cases, the air ducts inside the ventilation system can get clogged with dirt and grime. This happens if you use the ventilation regularly for a long time. However, it mainly depends on the amount of dust particles in your environment. <\/p>\n\n\n\n Regardless, it\u2019s an issue that can lead to major obstructions in the airflow system of your vehicle. It can close off multiple ducts altogether, forcing all the air to go out of the defrost vents. <\/p>\n\n\n\n To fix this problem, you need to open the air vents and clean them manually. We recommend getting professional help as you\u2019ll need expertise and tools to clean the ventilation system properly. <\/p>\n\n\n\n![\"Air](\"https:\/\/taxiwiz.com\/wp-content\/uploads\/2023\/11\/Air-Only-Blows-Through-Defrost-Vents-Causes-Solutions-1024x576.webp\")
<\/figure>\n\n\n\nWhat Causes Air to Blow through Defrost Vents Only?<\/h2>\n\n\n\n
Malfunctioning Mode Door Actuator<\/h3>\n\n\n\n
Faulty Blend Door Actuator<\/h3>\n\n\n\n
Blower Motor Damaged<\/h3>\n\n\n\n
Faulty Blower Resistor<\/h3>\n\n\n\n
Bad Relay<\/h3>\n\n\n\n
Blown Fuse<\/h3>\n\n\n\n
Vacuum Leak<\/h3>\n\n\n\n
![\"Vacuum](\"https:\/\/taxiwiz.com\/wp-content\/uploads\/2023\/04\/Vacuum-Leaks.webp\")
Clogged Air Intake <\/h3>\n\n\n\n