Why Does Car AC Blow Hot Air On One Side And Cold On The Other?

When you are getting into your piping hot car on a summer day or even trying to get it warmed up after a night of snow, the last thing you expect is unequal AC air distribution. You may start stressing when the car blows hot air through one vent and cold air through the other.  

Your car AC may blow hot air on one side and cold air on the other when the temperature blend actuator has failed or is damaged. The refrigerant inside the AC system may also have leaked out, causing the air to be cooled down unevenly throughout your car’s ventilation system.   

There are many reasons your car’s AC may misbehave; learning how to diagnose these issues will help you find the best solution. Many people have found that the settings on their AC also affect how the car is heated or cooled down, depending on your needs.  

Why Is Half The Car Blowing Cold Air? 

The first thing we recommend checking is how your car is heating or cooling down your car. If you have full climate control, your car will cool down and heat different sections of your car, creating the feeling that one half of the car is cold while the other is hot.  

When using normal AC, the car will only blow hot air out of one vent and cold air out of the other when the temperature blend actuator or the refrigerant coolant has leaked. When this happens, the car may only blow cold air out of one vent or stop providing cool air.  

Just checking where the cold air is flowing into or where there is only hot air will help you diagnose the issue. Just be sure your car doesn’t have seat-specific climate control that causes different temperatures depending on where people sit.  

Resetting The Blend Door Actuator 

The most common issue is always the blend door actuator inside the AC system; this part controls where the air inside the AC system is currently flowing. You often have to clean it out and reset the blend actuator doors to help the system take full control of everything.  

To reset the actuator, you must remove it from the dashboard where it is located and turn the AC to blow on full heat. Once hot air starts coming from the vents, turn the actuator and the vents to be fully open, or maximum, then reinstall the blend door actuator.  

Doing this ensures that the actuator knows where it is currently in and can adjust itself and everything it is connected to properly. Many people have mistakenly pushed the actuator to one maximum without setting the car to full heat first. 

How Do You Test The Blend Actuator? 

If you are unsure about the blend actuator being broken, there are a few ways to test whether it is broken. The most common way to test whether the blend actuator works is by turning the AC on full and listening to the sounds the ventilation system makes.  

When the blend actuator is breaking or not working, multiple clicking sounds will come from your car’s vents. This is because the motor that the actuator is using may just be failing, or the vents it is trying to close are too heavy for it to turn properly.  

It should be noted that many people specializing in fixing your AC system can tell when it has internal problems. Many modern cars even have sensors that know when parts inside the car are breaking down, with blend actuators usually one of the few parts that rarely give errors. 

Why Do Some Cars Always Have Different Temperatures On Each Side? 

Most modern cars have full climate control because these systems help with fuel efficiency, with the more advanced systems having zones. Each zone inside the car can be set to have different temperatures, allowing the car to keep everything comfortable for everyone.  

Many people moving to more modern cars after having driven their previous car nearly straight into the scrapyard can find this difficult to deal with. We always recommend that you read through the care instructions before assuming something is wrong with the car.  

Having these internal zones means that the car’s vents use different temperatures to control the climate. If you are the only one driving the car, we recommend that you set the climate control to one central zone to ensure that the car keeps you at the perfect temperature. 

Is It Normal For A Car AC To Blow Hot Air On One Side And Cold On The Other? 

If you have a normal AC system, it is not normal for the car to blow hot air out of one vent while blowing cold air out of the other vents is not normal. Normal AC should have the same temperature as the air being blown out of all the vents throughout your car.  

However, climate control systems will have different temperatures blown out of the vent systems. Further, the car will decide where to blow certain temperatures, increasing or decreasing the speed of the air coming out from each of the vents throughout your car.  

If you find that the car has a central knob or button that sets a specific temperature, you will find that the car has climate control instead of normal AC. Knowing what your car has will help you to understand whether or not the car should be blowing cold or hot air through different vents.  

How Do You Know If The Car AC Is Blowing Different Temperatures? 

If you suspect your car blows different temperatures through different vents, we recommend running a simple test. Doing this will allow you to know whether or not the AC is working as it should or whether you should take everything to fix it. 

Start the car and allow the AC to start working at half strength; full strength can cause mixed air issues. Once you are sure the AC is working, you need to hold the back of your hand in front of the different vents, feeling the differences in air temperature, if there are any.  

If you have a digital thermometer, you can use the room monitoring setting to see how hot or cold the air temperature from the vents is. The temperatures from each vent will not be the same but should only differ from three to four degrees Celsius.