Toyota RAV4 Defrost Not Working: Causes & How to Fix

The weather is freezing, and the windows and windshield of your Toyota RAV4 are all foggy. This can be pretty dangerous for you and others in your car. The logical thing to do is to turn on your car’s defrost system.

What do you do when this system isn’t working? We will teach you what to do to fix this problem in this post. Before then, let’s look at how the defroster works.

How Your Toyota RAV4’s Defroster Works

The defrost system of your RAV4 is essential for driving in poor weather conditions especially with poor visibility. With this system, you clear frost off your windshield and fog off the rear window. Let’s show you briefly how this system works.

The front defroster

This system uses the same venting system and blower motor as your air conditioning and heating systems. As such, the air moves through the core of the heater to the AC evaporator. This hits the windshield and removes the moisture from here.

All this air is released through the vents that are on the dashboard. This is how the front defroster removes the fog and humidity on the windshield.

The rear defroster

When you look at the rear window of your Toyota RAV4, you will notice some tiny lines. These lines run through horizontally from one end of the window to the other. The lines are actually wires and they heat up when current flows through them.

As these wires heat up, they transfer heat to the window to displace any condensation. Wondering if you could get burned by the wired? Not a chance. The heat they produce is very low.

Reasons Your Toyota RAV4 Defroster Isn’t Working

Now that you understand how the defrost feature works, it is time to see what could stop it from functioning properly. There are several reasons depending on whether it is the front or rear defroster. For the sake of clarity, we have split this section to discuss these reasons.

Front defroster issues

These are the possible reasons why the front defroster of your RAV4 are malfunctioning:

Malfunctioning thermostat

Your RAV4 has a thermostat like every other car. This part acts as a shut-off valve that mediates between your radiator and the car engine. The thermostat will remain closed until your car builds up heat.

After the engine gets warm, the thermostat begins to regulate the circulation of anti-freeze. This protects your engine from overheating. If the thermostat gets bad, the engine wouldn’t warm up. This means that the defroster cannot gather the warm air that it requires to perform optimally.

Blockage in the fresh air inlet

Fresh air plays a major role in the proper functioning of the defrost feature. The fresh air intake sits at the base of your windshield. Its function is to act as an inlet for fresh air to facilitate the defroster. Sometimes this inlet is blocked by debris like leaves and dust. When this occurs, it affects the proper function of the defroster.

Vent issues

In some cases, the problem is the vents. When the vents located on the dashboard get blocked, they prevent air from getting to the windshield. One way to solve this problem is to vacuum the vents. However, it is not a guarantee that the system will return to normal function. This is because the debris may have gone deeper into the system.

Stuck buttons

Sometimes, the knob or buttons that control the system get stuck. An easy way to solve this problem is to move the buttons back and forth. When they come loose, the system could start to function normally.

Bad blower

Your car’s defrosting and heating system rely on the blower motor for the movement of air. Without this part working well, the hot air will not get to the defroster vents. Some reasons why the blower may go bad include a bad speed controller or a blown fuse. It is also possible for the blower motor to stop working as well.

Low anti-freeze

The core of the heater requires hot anti-freeze to function optimally. When your car is low on anti-freeze, the defrosting and heating systems are likely not to function properly. It is important that you always check the anti-freeze. Once you notice that it is low, ensure that you replace it on schedule.

Bad heater core

Sitting right behind your RAV4’s dashboard is the heater core. This part functions like a mini-radiator and it is also the heart of your car’s heating system. Without the heater core, your defrosting system wouldn’t function properly. There are several reasons why the core may malfunction including contaminants, broken valves, and loose hoses. Without the core, there is no heat meaning the defroster wouldn’t work.

Rear Defroster issues

Why will the rear defroster of your Toyota RAV4 not function properly? Here are some possible reasons:

Damaged lines from tinting

When you apply tint to your rear window, it is possible that it will come in contact with the defroster lines. This may result in bonding between the tint and the heating elements. When this occurs, the tint is likely to break the defroster lines. Sometimes, the breaking of the lines occurs when you are trying to get rid of the tint.

Old age

As the defroster lines get older, there is a possibility of losing their conductivity. This means that they are no longer as efficient as they used to be with conducting electrical current. There are certain actions that may cause wear and tear to the lines. Examples include rubbing over the lines, repeated cleaning, etc. If this continues, the rear defroster will become inoperable.

Broken tabs

If you look closely at the edges of the rear defroster, you will notice some tabs. These tabs are the connecting points between the circuit and the window. One tab is the positive terminal and the other is the “earth.” When one of these tabs fail, your defroster will cease to function.

Broken grid

This is the most common reason why the rear defroster will stop working. By broken grid, we mean physical damage to the lines on the rear window. This damage mostly results from objects rubbing against the glass to break the grid wires. When this occurs, it opens the defroster circuit. As such, the defroster stops functioning at the point where it was broken.

Toyota RAV4 Defrost System Not Working: How to fix

Now that you’ve understood the likely problems with your Toyota RAV4’s defroster, it’s time to move on to fixing the problem.

It is possible to solve the problem yourself, but it depends on the complexity of the issue. To be honest, most of the issues with your defrost function will require professional help. We have already taught you how to fix the buttons when they are stuck.

Let’s take a look at how to quickly clean the vent – which is about the only fix you can do on your own.

Step 1 – Ensure that you have ample working space before you begin work.

Step 2 – Drain your AC before you begin working on the HVAC system.

Step 3 – Take apart your dashboard. You should begin from your stereo then move to the cluster at the side pillars. After taking these out, remove the dash pad. Ensure that you know exactly where you removed what. If possible, mark each screw and part so that you don’t forget.

Step 4 – Remove all the bolts and wires holding your car’s heater unit together.

Step 5 – Remove the HVAC unit.

Step 6 – Clean up the unit as much as possible. Get out all the debris and if you have a blower, use it to get rid of the dust as well.

Step 7 – Put everything back in place. Don’t forget to follow the labels that you made earlier.

For other issues, you may need to speak to a professional. After all, you can’t fix a broken grid or motor by yourself.

Wrap-up

Now you know how the defrost system of your Toyota RAV4 works. We have also explained the different reasons why the system could stop functioning. In the final section, we explained how to do a simple cleaning operation on the defroster vents of your car. We suggest that you speak to a specialist about other problems that you can’t fix on your own.