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Engine Cooling Fan Replacement
 
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Pelican Technical Article:

Engine Cooling Fan Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$600

Talent:

***

Tools:

T30 Torx driver, 10mm socket, Flathead screwdriver

Applicable Models:

Mercedes-Benz W211 (2003-09)

Hot Tip:

Work with a cool engine and clear DME fault codes when done

Performance Gain:

Proper engine cooling

Complementary Modification:

Inspect radiator and coolant hoses

Mercedes-Benz W211 models utilize an electronic cooling fan integrated into a cooling fan shroud. The cooling fan has an integrated control module to control speed via a control module. The engine cooling fan control modules are:

  • Vehicles equipped with a diesel motor: CDI control unit or the AAC control unit or comfort automatic air conditioning.
  • Vehicles equipped with a with gas engine: DME or the AAC control unit or comfort automatic air conditioning.

Depending upon the refrigerant pressure the AAC or comfort automatic air conditioning control module sends the following requirements to the fan:

  • Refrigerant pressure < 12 bar: fan in basic venting
  • Refrigerant pressure >20 bar: fan at maximum output
  • Refrigerant pressure 12 < 20 bar: fan continuously controlled

A/C compressor function, ambient temperature, and engine temperature are all used to determine fan speed and controlled via the appropriate module. Fan speed is controlled from a speed of 25% to 100%, depending on the requirement.

When repairing, the cooling fan and shroud are replaced as a unit. The cooling fan is responsible for maintaining proper engine coolant temperature and A/C cooling. When a W211 cooling fan fails, the fan will not activate or only activate at high speed. You can check cooling fan operation by turning on your air-conditioning and listening for the fan to activate. 

When replacing your electronic cooling fan, you will want to work with the engine cold and disconnect the battery negative cable. Disconnecting the negative battery cable will prevent the electric cooling fan from starting while being serviced. The fan could start at any time and personal injury can occur, don't skip this step.

Working in trunk, disconnect battery negative cable and cover battery terminal so cable does not accidentally come in contact with disconnected cable. See our tech article on battery replacing for notes on disconnecting and reconnecting battery.


The electric cooling fan on W211 models with a 6-cylinder engine is mounted to the front of the radiator (green arrow arrow).
Figure 1

The electric cooling fan on W211 models with a 6-cylinder engine is mounted to the front of the radiator (green arrow arrow). To access is, begin by removing the front engine cover and side intake ducts. 

Working at the engine cover (red arrow), pull off the two front sir duct hoses (green arrows).
Figure 2

Working at the engine cover (red arrow), pull off the two front sir duct hoses (green arrows).

To detach the ducts, pull the straight off the engine cover / air filter housing.
Figure 3

To detach the ducts, pull the straight off the engine cover / air filter housing. Then pull the front of the duct out of the radiator support and remove from the engine. Repeat this step for each duct.

Lift up and remove the front engine cover.
Figure 4

Lift up and remove the front engine cover.

 Working at radiator support, remove weather strip (red arrow). Pull weather strip off radiator support (inset) and place on engine.
Figure 5

 Working at radiator support, remove weather strip (red arrow). Pull weather strip off radiator support (inset) and place on engine.

Working at the top of the radiator support, remove the four plastic rivets (blue arrows), seven 10mm fasteners (red arrows) and the two T30 Torx fasteners (green arrows).
Figure 6

Working at the top of the radiator support, remove the four plastic rivets (blue arrows), seven 10mm fasteners (red arrows) and the two T30 Torx fasteners (green arrows).

To remove the rivets (red arrows), lever the center pin up, then pull the rivet out of the radiator support (inset).
Figure 7

To remove the rivets (red arrows), lever the center pin up, then pull the rivet out of the radiator support (inset).

Lift radiator support up to remove.
Figure 8

Lift radiator support up to remove. Then, flip radiator support over and detach the hood release cable (red arrows point to location of clips) from clips (inset).

Working at right side of cooling fan, disconnect cooling fan electrical connector by pressing release tabs (red arrows) and pulling apart.
Figure 9

Working at right side of cooling fan, disconnect cooling fan electrical connector by pressing release tabs (red arrows) and pulling apart.

Next the cooling fan retaining clips have to be removed.
Figure 10

Next the cooling fan retaining clips have to be removed. There is one at each corner. Using a flathead screwdriver, lever the clip up (red arrow) then remove (inset). Left side shown, the right side is similar.

Working at the left side of the cooling fan (red arrow), pull the coolant hose (green arrow) out of the mounts.
Figure 11

Working at the left side of the cooling fan (red arrow), pull the coolant hose (green arrow) out of the mounts. Then move to the right side of the fan and pull the hose of out of the mount, the hose is a bit lower and mounted in one holder.

Pull cooling fan up (green arrow) and remove from engine compartment
Figure 12

Pull cooling fan up (green arrow) and remove from engine compartment. Be careful not to snag fan on wires or hoses. When installing new cooling fan. Slide down into engine compartment, move into place then install retaining clips. Be sure fan is properly seated in radiator support. If fan is giving you a hard time and will not drop all the way down, check to see if bottom of cooling fan is hung up on the radiator or hoses. Reroute wiring harness and connect. You can check operation by running engine and turning on A/C, cooling fan will run when A/C is switched ON.

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Comments and Suggestions:
Scharpe Comments: This still needs to be fixed and I'm going to require these instructions ASAP!!!
January 23, 2016
  Followup from the Pelican Staff: It's in the queue to be fixed. - Nick at Pelican Parts  
Daine Comments: Hi. Just a heads up. Engine fan replacement segment has window regulator explanation.
Thanks.
July 1, 2015
  Followup from the Pelican Staff: Thanks for catching that. I will have it fixed. - Nick at Pelican Parts  

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