Is your air conditioner blowing only from the floor outlets, and you want to know what you can do to fix it? You’ve come to the right place, for we have researched this question, and we have the answer for you.
If your car air conditioning system is run by vacuum, a leak on the vacuum lines will cause the air conditioner to default to vent only to the floor vents. Look for the leak and patch it to fix the problem.
We will look more closely at this problem because there are different versions of it based on how your car controls the air vents. Learn all about them in the succeeding sections. Read on!
Why does my air conditioner suddenly shift to blowing on my feet when going uphill?
The air conditioner in your car helps make your trip on warm roads more comfortable. Car air conditioners achieve this in the same way as your home air conditioners.
How do vacuums work in a car air conditioning system?
There is a hose that connects to the engine where it creates a vacuum. Another hose connects to a reservoir, and a third hose goes to several vacuum actuators inside your car's cabin. Once your car gets to a high RPM—like when you’re going up an incline, pulling a heavy load, or doing a hard acceleration—the engine produces less vacuum.
When the engine produces less vacuum at high RPMs, the check valve shuts off the connection to the engine to prevent losing vacuum to the engine. This is when the vacuum stored in the reservoir takes over the duty of providing a vacuum to the air conditioning system to control the air doors.
How does a car lose vacuum when traveling uphill?
The vacuum coming from the engine is more stable than the one coming from the reservoir. Thus, when the check valve isolates the engine at high RPMs, you will expose a leak in the system because the reservoir will not be able to provide the same constant vacuum as the engine. This will result in insufficient vacuum to trigger the vacuum actuator valve.
The vacuum actuator valve is a switching mechanism for cars that use the vacuum from the engine to control where the air conditioner will blow the cold air. The vacuum actuator closes and opens the air door to redirect col air where you want them to be.
If there is an insufficient vacuum, the vacuum actuator will remain at its default position. In some cars, this is to open the vents to your feet, while some default to defrost, and some combine both.
How to fix a leaking vacuum control air vent system?
To be able to find where the leak is, you will need a vacuum gauge and a smoke machine.
- The vacuum gauge will allow you to test the rubber tubes by isolating them one by one.
- The vacuum gauge will start to drop once you connect it to a leaking rubber tube.
Once you identify which rubber tube has a leak, connect that tube to a smoke machine. Smoke will escape from the leak in the rubber tube, and this will tell you where the leak is. You can patch the leak with a vacuum tube patch, or you can trim off the leak and connect the two parts of the tube with a vacuum connector.
However, without a vacuum gauge and a smoke machine, your only option is to bring your car to a certified mechanic to locate and patch the leak for you.
Why does my air conditioner blow only on my feet?
This situation is similar to the first. However, since the air conditioner is only blowing to the floor vents regardless of whether the car is accelerating hard or not, this means that the leak could be somewhere between the switch valve and the engine.
If the leak is somewhere between the switch valve and the engine, then the vacuum actuators will never get the right amount of vacuum to work properly and will default to blowing only on the floor vents.
You will still need to use a vacuum gauge and a smoke machine to verify. This will allow you to make sure that there are no other leaks that you need to patch since your system is losing a lot of vacuum.
Again, without these two tools, you have no choice but to bring your car to a mechanic or a service center to test the rubber tubes, locate the leaks, and patch them.
How to fix an air conditioner that only blows on feet -without a vacuum control air vent system?
Some cars don’t use a vacuum control air vent system and instead use a manual air vent control. This system changes the direction of the cold air when you change the position of the control knob.
However, this system can fail when there is insufficient grease and when the telescoping air distribution control shaft that transfers the movement on the knob to the air doors breaks or comes loose.
Once the telescoping air distribution control shaft breaks, you will no longer be able to change the position of the air doors. If the last position is to blow cold air only on the floor vents, then it will stay that way until you replace the broken part.
When replacing any part on your car, it is important to get the exact part number to ensure that you are getting the correct replacement part with the correct measurements. Using the wrong part can damage other parts of your car and cause a bigger problem.
You will need to remove many parts of the dashboard to replace the telescoping air distribution control shaft. You can get the service manual for your particular car model to learn how to properly remove the parts of your dashboard to get to replace the problem part.
Alternatively, you can bring your car to a mechanic to replace the part for you.
Why does my car AC only work on low?
There is a resistor on the blower motor that controls the amount of electrical energy that goes to the motor. When you select a faster blower speed, the resistor will allow more electrical energy to get to the motor. However, if the blower resistor is starting to fail, it will no longer be able to allow the right amount of electrical energy that matches the speed that you want.
In most cases, the only speed that will work is the default speed.
A blower resistor is a small electrical part that is often hidden under the other components of the air conditioning system of your car. When the blower resistor fails, it is best to have a mechanic check your car for other problems that could be related to the failing blower resistor.
Why is the air not coming out of my car vents?
There are several reasons why there is no air coming out of the vents of your car. Let’s look at each possible cause closely.
Blown Fuse
A blown fuse will prevent electrical energy from reaching the blowers. Check your car manual to locate the fuse box and identify which fuse controls the electrical current to your blower.
Check if the fuse is blown or not. When replacing the fuse, make sure that you get a fuse that has the same ampere rating. Alternatively, you can bring your car to a mechanic to check any underlying reason why you had a blown fuse.
Failing Blower Motor
If all the fuses are intact, then the next possible cause is a failing blower motor.
If you have a failing blower motor, the most common solution is a replacement. It is best to bring your car to a certified mechanic to resolve this problem. The blower is often installed in a hard-to-reach area of your car.
Failed Blower Resistor
We talked about a failing blower resistor earlier. If the blower resistor fails and blocks all electrical energy, then your blower motor will not receive the electrical energy it needs to work properly.
This is one of the reasons why it is best to bring your car to a mechanic to check the blower motor—so that they can also check the other components that might also be failing.
Clogged Air Intake
Another cause of this problem is clogged air intake. Most car owners are not aware that there is an air filter that keeps dirt out of the air that gets into your air conditioning system.
Too much dirt on this air filter will reduce airflow getting into the system and result in very little air coming out of the vents of your car. Air filters in some car models can be cleaned while others can only be replaced.
Conclusion
If your air conditioner is only blowing on your feet, then there could be a problem with the controller of the air doors that channels the cold air to the correct vents.
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