What is the procedure to replace a Mercedes Benz radiator fan?

This article will explain the procedure to replace a Mercedes Benz radiator fan and answer the following questions: when to replace a Mercedes Benz radiator fan? What are the suitable aftermarket radiator fans available for replacement? Why should you use a Mercedes Benz genuine radiator fan? Is it necessary to replace the radiator fan?

What is the procedure to replace a Mercedes Benz radiator fan?

The procedure to replace a Mercedes Benz radiator fan is as follows:

• Disconnect the ground terminal of the main battery and remove the electrical coupler on the radiator fan.
• Disconnect vacuum lines to the radiator shutter actuator if any.
• All the radiators are mounted in 4 locking hooks, two on each side.
• Dismount the transmission oil cooler located on the radiator fan housing.
• Apply slight pressure and pull the radiator fan housing upwards to release the locking points.
• Insert a thin sheet metal plate between the radiator and the fan. This is to protect the radiator fins from damage while removing the fan.
• Guide the fan carefully between the coolant hoses and remove it from the backside of the radiator.
• Installation can be done in reverse order.

The procedure will be the same for all the latest models, in some models it may be required to remove the top cover on the radiator to remove the radiator fan. Therefore, the battery must be disconnected and any loose clothing item like a necktie or coolant pipe mustn’t come in contact with the radiator fan when the engine hood is open.

The fan motor and controller are fixed in the fan shroud and cannot be replaced separately. Therefore, if there is any fault in the fan motor or the radiator shutter the complete fan housing is replaced.

When to replace a Mercedes Benz radiator fan?

In case of an electrical or mechanical fault in the radiator fan, the radiator fan needs replacement:

Electrical fault-

If the initial quick test of the vehicle has a fault code related to the electrical fan motor, then the complete radiator fan must be replaced as the fan motor cannot be replaced separately. Inoperative fans will cause the coolant to overheat and evaporate.

If there are fault codes related to the missing LIN signal from the powertrain control unit, it can cause the fan to not run. Coolant warning is also shown in the instrument cluster of the vehicle.

The reason for the missing communication between the powertrain control unit and the microcontroller in the radiator can be an open circuit or a short circuit in the electrical lines.

The electrical lines must be repaired according to the standard working procedure to rectify the fault. The radiator fan sometimes can start at full speed as soon as the ignition is turned on. 

It is due to a fault in the vehicle communication network and must not be confused with a malfunction of the radiator fan,

As the coolant system is pressurized, the coolant level can go down significantly and damage critical components like the cylinder head gasket. Hence, if a coolant malfunction indication is on the instrument cluster, do not operate the vehicle and consult the workshop.

Mechanical fault– 

If the fan blades are damaged due to flying debris or the central bearing is mechanically jammed, abnormal noise can come from the fan. The fan can also get misaligned and damage radiator fins.

It is possible to check the fan at full speed by an actuation signal from the Xentry diagnosis tool. Fan blades or bearings cannot be replaced separately. The bearing can overheat if the fan is operated at high speeds for longer durations.

What are the suitable aftermarket radiator fans available for replacement?

Some of the suitable aftermarket products available for replacement of the original Radiator fan are listed below:

Mercedes Benz does not recommend the use of a non-genuine radiator fan. A genuine radiator fan can only be purchased at authorized Mercedes Benz dealerships. If the genuine part is purchased by the customer, Mercedes Benz even gives a two years part warranty.

Why should you use a Mercedes Benz genuine radiator fan?

You should always use a Mercedes Benz Genuine radiator fan because there is a microcontroller that operates the radiator fan. It can increase or decrease fan speed based on the coolant temperature.

The Powertrain control unit controls the microcontroller via a LIN signal. Coolant temperature measured by the coolant temperature sensor is monitored by the powertrain control unit and based on the coolant temperature the radiator fan speed is controlled. 

The coolant temperature sensor is an (NTC) negative temperature coefficient type sensor located on the cylinder head to accurately measure the coolant temperature. 

The radiator fan also has flaps called radiator shutters. Flaps cover the surface of the radiator and are operated by a vacuum actuator. 

By closing the flaps air does not flow over the surface of the radiator and coolant can heat up faster which is then pumped back into the engine and the operating temperature is reached more quickly.

Is it necessary to replace the radiator fan?

Yes, A radiator fan must be replaced in case it is not working correctly. The vehicle operates at different speeds through the city and highways and it is not possible to ensure a steady flow of air across the radiator.

If there is no steady airflow across the radiator fins then the coolant cannot be cooled and the vehicle will overheat. Over time the radiator fins can be blocked by dust and insects which will reduce efficiency and cause the fan to operate at higher speeds. 

Hence the radiator should be cleaned regularly with hot water to maintain its cooling efficiency and the fan must be replaced if it is faulty.

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Conclusion 

Mercedes Benz radiator fans can be replaced within an hour thanks to their clever design. The cost of radiator fan replacement is around 400$. Although faults in radiator fans are rare, electrical or mechanical malfunction can occur. Replacing faulty parts with a genuine part will guarantee long service life, Mercedes Benz also offers a parts warranty if the Fan is replaced on a chargeable basis.