Mercedes Sprinter Heater Blower Motor Brush Replacement


Intermittent or no rotation of the heater blower fan is a common problem on the Mercedes Sprinter.  As similar types of fan motor assembly appear on many Mercedes models the replacement of the carbon motor brushes is much the same across the range once the motor is removed. Link to motor brushes suitable for Sprinter and other Mercedes blowers here.

First be sure that the appropriate vehicle electrical supply exists on the fan DC connector and check all circuit fuses before assuming the fan itself requires repair.

Mercedes Sprinter Blower Motor

On the Sprinter, start by unplugging the electrical connector from the base of the fan assembly in the passenger side engine compartment.  Remove the 3 cross head self tapping screws that hold the fan/motor assembly to the blower box then withdraw it downward, removing the unit out from the vehicle. Placing the unit on the floor or workbench, begin to release the motor and fan from the plastic body. This is done by inserting a broad flat blade screwdriver into the 3 openings as shown and levering the units rubber mountings complete with motor out of the cover body.  You will need to keep working your way round the holes levering as you go until the assembly works its way out from the cover body.

Removing motor assemblyFan and motor removal

Once the motor and fan are separated from the cover, place the unit on a flat surface – fan side down – and locate the two brush holders as indicated on the photograph below.

Mercedes Sprinter Motor Brushes

The carbon brushes (A) and braid (B) transfer the electrical energy to the rotating motor commutator and because they are always in contact with the spinning rotor they wear down over time and no longer make satisfactory contact, the motor either becomes intermittent or ceases to work at all.  The high cost of a replacement fan motor assembly from Mercedes  or Auto-factor, makes this an ideal candidate for an economical DIY repair that is quite simple and not too taxing.  Start by obtaining new motor brushes from many of the on-line auction sites available on the internet.  The brushes are standard size across the range of motors used by Mercedes and also many other manufacturers – so are quite common.  The size you need are 9mm x 8mm x 22mm with a braid wire of at least 40mm in length.  You will need a pair and these cost little more than £5 with postage.

Mercedes Blower Fan Brushes

Once the motor/fan assembly is removed from its cover the brush gear is easily seen. First begin by straightening the retaining bars on the brush holders with a pair of long nose pliers, the material is quite soft so bends easily, take care not to break them off!.  These are indicated by the white arrows on the photograph below.

Mercedes Blower Motor Brush Removal

Once the two sides are straight the brush retaining pressure spring will be released, cut the existing braid wire about 12mm from where it is soldered to the electrical contact post and remove the brush by pulling the braid upward.  Once the brush is removed, note which side has the pointed longer edge as the new bushes will have to be fitted in the same way as these were removed.  If you do forget – look at the brush holder and you will see that it is mounted off-centre to the centre line of the commutator shaft, the longer edge of the new brush goes to the holder edge furthest away from the shaft centre line as you insert it.  You may find that the universal brush kit you have purchased has brushes that are a little too long.  This is easily rectified by using a junior hacksaw and trimming the brush length as indicated in the photograph below.  Be sure to maintain the angle of the brush tip and dress the carbon block with a small file to a round it to a slightly concave profile similar to the one on the part just cut off and disgarded.

Mercedes Carbon Brushes

 With the old brushes now removed scrape clean the interior guide faces so the new parts will slide easily within them, also scrape the tip of the braid previously cut with the edge of a small file.  Removing the carbon dust and cleaning this copper braid will allow solder to be applied and make for easy joining/tinning of the new braid to this point using a soldering iron and multi-core solder.

Insert the brush into the holder with the longer edge in the correct position as outlined above.  Thread the braid through the centre of the coiled spring and compress it fully into the brush holder below the level of the slots beneath the retaining bars.  Using long nose pliers, distort the retaining bars inwards to block the spring under tension within the holder.  Using a soldering iron, join the new braid to the existing cut stub and tuck its free length neatly into the motor housing void, making sure that it hangs free not touching any metal part of the motor, rotating armature or steel housing.  Complete this on the other side of the motor and once the pair have been fitted begin to re-assemble the motor into the plastic cover.

Align the power connector so that it will appear in the correct position within the cover once assembled.  Slot the three rubber mountings into their respective grooves and push the motor home.  As the motor reaches full insertion in the cover, use a screwdriver to push the rubbers  fully home and latch them into the retaining holes in the cover.  This can best be done as shown in the photograph, from inside the fan blade cage pushing downward into the case body.

Mercedes Sprinter Blower Motor Assembly

Once the motor and fan assembly are latched fully back into the plastic cover the completed unit can be refitted into the vehicle, reconnected and tested.

16 thoughts on “Mercedes Sprinter Heater Blower Motor Brush Replacement

  1. B Class Mercedes.

    B180 Diesel, Manual. 2007.

    Heater blower has stopped working on 1,2,3 and 4.

    Will ONLY work on 5/Max.

    Air Con recently repaired. Worked fine for about 3 weeks.

    Any ideas??

    1. Hi Will,
      The chances are that the blower motor speed control resistor module is faulty, its been previously reported as occuring on this model. Have a read here – I am sure it will help you out. There is the outside chance that some wiring had been disturbed or poorly reconnected during the recent work done to the AC. Well worth a full check out before you cast all your doubts on the resisteor module itself.
      All the best

  2. Thanks so much for sharing this!!!! It worked for me perfectly i didnt replace the carbon contacts yet but just sanded the surfaces.

  3. While you have it apart lube the bearings. I am good with white lithium spray grease, the solvent lets the grease into the bearing then evaporates. Blower motor dry bearings are common and will eventually destroy the motor fan a penny now will save a pound later not to mention years of squealing less than great blower operation.

    1. Thanks for the link Shabbir, I have looked at the site and its a great source for UK brush parts! – Even the workshop drill or the wifes vacuum.. 😉
      All the best

  4. my 2006 Sprinter blower in dash stopped working. I checked 30amp fuse and it was blown. I put a new fuse in and it blew right away. what could be wrong?

    1. Hi Tony,
      It sounds as if the motor has seized and/or is jammed. Bearings begin to bind and eventually the bronze bush tightens to the point of not allowing any rotation, result it burns out the motor – if you are lucky it will just take out the fuse but generally when this happens the damage is done. Put your hand inside the fresh air inlet under the hood/bonnet and try and turn the fan, this will confirm the problem. The fan and motor unit is easily removed by undoing the three cross head screws from beneath the inlet box and dropping the unit down. There is only one electrical connector to unplug on the side of the motor unit. You can now fully inspect the unit and see if it can be repaired.
      Hope this helps

  5. Hello Steve,
    I found you on the Sprinter forum and followed to here. Thank you for taking the time to write an article and add great pictures.

    Can you tell me the part number or size for the brushes? It looks like there is too much end play on my motor. it is causing the fan cage to rub against the body. I am planning on adding a felt and a washer unless you have a better idea.

    Does anyone have part number or source for the bushings?

    Best regards,

    1. Hi Nolan,
      The brushes you need are: 9mm x 8mm x 22mm with a braid wire of at least 40mm in length. EBay will probably be the best source. This UK seller ships world wide
      I imagine the fan blade unit has begun to foul the back plate possibly because the rubber attachment has become slack or distorted. Try removing the motor as pictured from its rubber holder and replace it a different position to maintain a better clearance of the back plate. As the motor spins with its shaft vertically I doubt shaft movement will be an issue as it will always be forced to rotate in one position thanks to gravity.

      Have a go and see how you go on repositioning the fan motor in the rubber mount. Fan blade to back plate clearance is not usually more than a quarter of an inch.

      I doubt bronze bushes are available, probably a new motor would be Mercedes solution – personally if it came to that I would obtain a used replacement part from a breakers yard.

      All the best

      1. on 2006 sprinter my heat will not blow on any setting. Checked fuses they are ok. AC works but blows slower on all fan setting. Fan started working again for several hours then went out again.
        Fan spins ok when spun by hand with circuit off.

        if blower is bad why does it spin on ac and not heat?


      2. Hi Mark,
        It is quite often the case when the motor brushes are on their way out this happens. One day it will work the next it won’t. often slower. Sometimes the motor develops a dead spot, needing a jolt or bump in the road to start it going again. I would undo the three screws and take the motor out and have a look at the brushes.

        Your 2006 model, if the motor has not been attended to already, will I would have thought be due for a spring-clean and re-brush. It may be worth while checking the dropper resistor that controls the fan speed in the top of the fan air box, sometimes the contacts corrode and make a poor connection because of where it is situated. However if this was the problem all would be fine on hi-speed (direct connection) and problematic on the lower speeds, so still pointing to motor issues.
        Hope that helps
        All the best

  6. This is all useful information. It enabled me to prove that my heater blower motor works fine by connecting 12v direct to the motor. However I still can’t run the blower from the dash switch. My van is a Rapido motorhome based on a 2000 reg Sprinter 312d. The dash switch has power (red light when air set to recirc). I checked all the fuses in the box under the steering column, and the fuses in the relay box under the driver seat. All are ok.
    The wiring diagram shows a resistor box for the blower motor speed control. Where is this resistor box?
    I’m avoiding dismantling the dashboard unless I have to!
    Any help or suggestion gratefully received.

    1. Hi Ian, The resistor for the blower lives in the heater duct above the fan unit under the hood/bonnet. If you look under the bonnet at the blower motor housing look up and to the slight left and you will see a bunch of thick wires to a clip in unit, this is the resistor that controls the fan speed. It has a mounted fuse that blows rendering the unit useless if the motor load has become excessive. It just slide latches out of the ducting for replacement or inspection.
      All the best

      1. Thanks Steve. Yes, I can see the resistor block, but it is fastened in with two screws: front and rear. I can get the front screw out, and disconnecting the cables I can just see the rear screw, but can’t get at it with a tool to get it out. It might not be that anyway!
        Might have a go at the dashboard switch. Might invent a workaround. We only need it when the windscreen mists when we set off. There is another heating fan for the motorhome space which runs off the engine cooling system to warm the space.
        Thanks for the help anyway

        Ian mac

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