If the blower motor in When your Mercedes Benz vehicle stops working, your first thought might be to take it to your dealer.
But fixing a bad blower motor doesn’t always need expertise. In most cases, you only need to know what to check, test, or change to repair the device. And you can do it yourself.
The problem is: where do you start? That’s why I’ve written this article.
In this post, I’ll help you diagnose the issue with your blower motor. You’ll also learn how to fix each issue and get the motor to resume working.
Causes of Mercedes Benz Blower Motor Issues
When a fuse in your Mercedes Benz car gets blown, the vehicle will develop a short circuit. This means that your blower motor, alongside other electronic devices in the vehicle, will not have enough power. As a result, the motor might stop working.
To check if you have a blown fuse, use a long-nose plier to remove the fuses in your car. Then, hold each fuse against a light.
If the metal strip at the center of a fuse is broken, the fuse is blown. As such, you’ll need to replace the fuse.
Bad Blower Motor Relay
Another common reason why a Mercedes Benz blower motor stops working is a faulty blower motor relay.
Your blower motor doesn’t turn on immediately after you’ve switched on your AC. Rather, the motor has a relay that activates it after your AC has started running. This relay may develop problems after you’ve used it for several years.
When the blower motor relay is faulty, it might fail to turn on the blower motor. Your blower motor will stay off until you replace the relay.
Faulty Blower Motor Resistor
If your blower motor resistor is bad, your blower motor may not work.
After the relay has activated the blower motor, the motor needs to know how fast it can run before it starts working. The blower motor resistor determines the appropriate speed and sets the motor to run at that pace.
As the resistor ages, it may start malfunctioning. This issue might prevent the blower motor from working.
The only way to solve this problem is to change your blower motor resistor. But before you replace the resistor, you might want to confirm that the component is bad.
You can check if your blower motor resistor is still working by inserting its probes into a multimeter. If the voltage count is more or less than 12 volts, the resistor is dead.
Your blower motor can’t work if its wires are in bad shape.
Even when your blower motor and its components are still new, water can leak into your vehicle and destroy the wires. In addition, rodents may creep into your car and bite the wires.
A rusty or broken wire won’t deliver sufficient electrical current to your blower motor. Without enough electricity, your blower motor may stop working.
Check your wires for signs of corrosion and rodent bites. If you discover these marks on your blower motor’s wires, you’ll need to change your wiring connector.
Bad Blower Motor
Sometimes, the blower motor might be the source of its own problems: it may have reached the end of its lifespan.
When your blower motor is faulty, you may hear whirring noises from the dashboard. But relying on such noises alone is insufficient, as they can also indicate a problem in another AC component.
A more effective way to tell that your blower motor is bad is to connect the motor to a 12-volt battery. You can use an alligator test cable to link both devices. If your blower motor doesn’t spin after you’ve made the connection, it is most likely faulty.
Replace your blower motor if you suspect that it is faulty.
Broken Climate Control Unit
Another culprit that can prevent your blower motor from working is a faulty climate control unit.
When you turn on your fan, the climate control unit delivers the signal to the blower motor resistor. In turn, the resistor starts operating the blower motor.
Like other components in your vehicle, your climate control unit can develop issues. When this happens, it may stop delivering your commands to the blower motor resistor. This means your blower motor might stay off.
Hire a mechanic to inspect your climate control unit if you think the system isn’t working properly.
How to Fix a Mercedes Benz Blower Motor that Stops Working
Change Your Blown Fuse
If your Mercedes Benz blower motor stops working, changing a blown fuse might fix the problem.
First, inspect all the fuses under the dashboard. If any fuse looks blown, replace it. You can tell that a fuse is blown if the metal strip at the center of the fuse is broken.
Usually, the fuse that controls the blower motor is either a 20amp, 25 amp, or 30 amp fuse. This fuse is often located underneath the driver’s dashboard. That said, it’s best to focus on the fuse box below your dashboard when checking for blown fuses in your car.
Before you replace the bad fuse, make sure that the new one has a similar color and amp rating.
Replace Your Blower Motor Relay
Replacing the blower motor relay is another way to troubleshoot the problems in the motor.
Study the fuse diagram in your owner’s manual to locate your blower motor relay. Once you know what the relay looks like, search for it in the fuse box under your driver’s dashboard. If the relay isn’t in the under-dash fuse box, locate it underneath your hood.
After spotting the relay, test it with a multimeter. If the voltage on the multimeter reads above or below 12 volts, change the relay.
Change Your Blower Motor Resistor
You can also fix a faulty blower motor by changing the blower motor resistor.
Here’s how to replace the blower motor resistor in a Mercedes Benz car:
- Locate your passenger side footwell.
- Remove the kick panel on the footwell to reveal your blower motor resistor.
- The resistor is the component on the right side of the footwell.
- Squeeze the tab on the blower motor resistor to remove the electrical connector underneath it.
- You’ll notice a knob on the resistor.
- Place a pair of pliers on the knob.
- Twist the knob with the pliers to detach your blower motor resistor from the vehicle.
- Take your old blower resistor out and get the new one.
- When replacing the resistor, make sure the round part faces forward.
- Tighten the knob on the resistor.
- Reattach the electrical connector and close the kick panel.
Change Your Connector
If the wires on your blower motor are rusty, it might prevent the motor from working. To solve this problem, replace the connector on the faulty wires.
You’ll need a wire stripper, electrical tape, a pair of pliers, and a soldering iron to do this job.
The guide below will show you how to replace the connector on your Mercedes Benz blower motor:
- Cut the wires close to the end of the connector.
- Get the new connector.
- If the wires on the new connector are too long, trim off a small piece.
- You need enough exposed wire to connect your blower motor’s wires to the wires on the new connector.
- Use a wire stripper to remove some of the insulation on both wires.
- Now, twist the exposed parts of the wires together.
- Solder the joint wires with a soldering iron.
- Now, wrap electrical tape over the joint to secure it.
Replace Your Blower Motor
Your blower motor may have stopped working because it is dead. In that case, you’ll need to replace the device.
Take these steps when replacing your Mercedes Benz blower motor:
- Remove the kick panel on your passenger side footwell.
- The blower motor is directly below it. Use a T20 torx drive to pull out the mounting bolts on the motor.
- Slide the blower motor down.
- You’ll notice a plug connecting the motor to the footwell light.
- Remove this plug.
- You may also find another connector linking the blower motor to the temperature sensor on the footwell. Detach this connector.
- You can now remove your blower motor.
- Get the new blower motor and connect it to your dashboard.
More details on how to replace the blower motor on a Mercedes Benz (E350, E500, E63 AMG, etc.) in the video below:
Replace Your Climate Control Unit
If your blower motor doesn’t work after you’ve tried all the tips above, the issue might be from the climate control unit. So, you should consider changing the unit to see if that would fix the problem.
We don’t recommend replacing your Mercedes Benz climate control unit yourself. If you do, you might damage some of the electrical connections in your vehicle.
Hire a professional to replace your climate control unit if you suspect the system is faulty.
Several factors can make your Mercedes Benz blower motor stop working. These issues include a blown fuse, a bad relay, and broken wires. Other reasons why your blower motor may stop working are a defective blower motor resistor and a bad climate control unit.
Your Mercedes Benz blower motor should start working after you’ve applied all the solutions here. However, if the device fails to work, contact your dealer for help.