Several larger vehicles, including the Lexus RX 350, contain rear vents mounted between the two seats. These are connected with the air conditioning system to make the passenger comfortable. Larger front seats block the cold air and prevent it from moving back. Rear vents are beneficial to keep the back side cold and provide them more comfort.
Lexus RX 350 rear vents not working can be due to damaged vent buttons, closed vents, damaged wiring system, faulty climate control, low refrigerant levels, damaged blower motor, clogged vents, and faulty blower resistor.
I faced the issue on a long trip with my family a few weeks back. It was a hot morning in summer, and the rear vents stopped functioning. It was a scorching summer day, and my children felt uncomfortable during the journey because of the hot temperature.
We temporarily opened the windows for better airflow, but it could not work. I closed the rear windows and turned on the air conditioner fan at high speed to maximize the airflow and temperature.
| Problems | Solutions |
| Damaged rear vent button | Replace damaged operating buttons |
| Closed rear vents | Keep rear vents open |
| Damaged wiring system | Check battery power to reduce voltage fluctuation issue |
| Faulty climate control system | Regular maintenance of AC units |
| Low refrigerant levels | Refill refrigerant |
| Damaged blower motor | Blower motor replacement |
| Clogged vents | Blow compressed air or hair dryer |
| Faulty blower resistor | Ensure smooth voltage supply |
Damaged rear vent button
You have to enable the rear vents from the button located on the cluster screen. In addition, some Lexus RX 350 models do not contain this button, and you have to activate this from the settings menu.
These vents stop blowing cold air because of their damaged buttons. You cannot turn them on because of their damaged buttons.
Their buttons can break because of incorrect handling and their regular use. Chances of age-related wear and tear of this part increase because of their frequent use.
Many people turn these on and off frequently to maintain the temperature. These buttons contain springs that can break because of their consecutive usage.
Water can also spill on them and seep into their internal components. Moisture exposure damages their internal electric components and increases the chances of corrosion.
Buttons can also break when you press them forcefully. Dust and dirt can also come on the sides of these buttons because of poor cleaning practices.
Dust can also cause them to get stuck, and you cannot turn on the rear vents. The issue also comes because of the faulty control module.
You can face this problem because of malfunctioning touch screens and software bugs. It is necessary to replace the damaged operating buttons with new ones.
Moreover, keep the software of your SUV updated when you have to activate and deactivate the rear vents. Avoid drinking water or liquid beverages during driving because these can spill on the interior components and lead to severe damage.
Closed rear vents
Rear air conditioning vents cannot blow the cold air and maintain the interior cabin temperature when these are closed.
You can open and close them by sliding upward and downward. In addition, you can also move their grill in different directions by sliding it forward and backward.
Many people unintentionally close the rear vents for temperature maintenance and then forget to open them again. They become worried when the interior becomes hot and think the rear side vents are malfunctioning.
However, the issue also comes when sliding grills get stuck in the closed position. These can get stuck because of their broken parts and poor lubrication.
You should ensure that the rear vents of your Lexus RX 350 are opened when you turn on their operating switch.
Damaged wiring system
Rear vents are connected to the main air conditioning system through wires. These wires supply power to these vents to blow the cold air.
These parts also increase the overall fuel consumption of your SUV because air conditioners need more to blow cold air in front and rear vents.
However, they also stop functioning because of damaged compressors. Frayed wires cannot supply sufficient power to the blower motor. These wires can break because of their age and damaged insulated coating.
Short circuits and fluctuating temperatures are responsible for damaging the insulated coating. You should check the batteries in your vehicle to ensure smooth current flow and reduce the chances of voltage fluctuations.
Faulty climate control system
The climate control system in your vehicle is connected to the air conditioning system to maintain the interior cabin temperature. Sometimes, people set the temperature at the optimal range, and the function of climate control is to adjust the temperature at the selected range.
The rear vents stop functioning because of a faulty climate control system. The faulty system is not helpful to maintain the temperature through the rear vents.
Climate control systems become faulty because of damaged temperature sensors. In addition, the issue also comes because of the failure of the climate control module.
Moreover, damaged blower fan motors, refrigerant leaks, and faulty relays also affect their normal functioning. You can reduce the likelihood of the climate control system malfunctioning by scheduling regular maintenance.
Keep the air filters clean and replace the dirty filters with new ones. Check the refrigerant levels daily and refill them when their levels become low.
Low refrigerant levels
Most SUVs use Freon as the refrigerant, responsible for blowing the cold air through air vents. This refrigerant is helpful to remove the heat and moisture from the air.
I also faced the issue because of the low refrigerant levels of my vehicle’s air conditioning system. I was traveling with my friends on the road in the scorching heat of summer.
All of a sudden, the rear vents started blowing warm air. I checked the refrigerant level, which was low, so I refilled it in my SUV.
Refrigerant levels decrease because they regularly use holes or cracks in the air conditioning system. It is an odorless liquid with a light green tint. After seeing that liquid, you should inspect the air conditioning system parts of your Lexus RX 350.
Damaged blower motor
The blower motor is mounted on the dashboard, allowing cold air to blow through the front and rear vents. Because of its damaged parts, the blower motor does not blow the air through these vents.
These vents do not turn on when you press the operating switch because of faulty motors. The blower motor becomes bad in the Lexus RX 350 because of the overheating issue.
In addition, poor ground and electric connections also increase the risk of damage to blower motors. These become faulty because of blown-out fuse, voltage fluctuations, and dirt accumulation on their parts.
Blower motor damages are reversible, and you have to replace it with a new one. However, proper lubrication and sufficient voltage supply decrease the chances of damage.
Clogged vents
Rear vents stop blowing cold air because of the clogging issue. Dust and debris from the surroundings increase their clogging chances. Debris accumulation blocks the smooth airflow through their opening.
Moreover, mold growth also increases the chances of clogging. Molds can grow on them because of moisture and poor routine maintenance.
I also faced an issue in my SUV because of clogged vents. My friend told me to blow the compressed air in their vents to remove the dust and debris particles.
You can also use the hair dryer by setting their heat to a minimal level.
Faulty blower resistor
The blower motor resistor is a part of the blower motor that helps adjust the fan speed. Damaged resistors cannot adjust the fan speed, and rear vents stop blowing cold air.
Blower motor resistors are vulnerable to failure because of their constant use for longer periods. In addition, prolonged exposure to high temperatures from the blower motor can also cause the resistors to burn out.
Water and moisture exposure from the air conditioning system also affect their normal functioning. It is necessary to check the Lexus RX 350 electric system to ensure the correct voltage supply for its smooth functioning.
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