Strange Behavious W124 Blower

[shanksy]

Hi all,

The heater blower in my W124 coupe has decided to pack in (just as its started to get colder again), so am planning to remove the wiper assembly at the weekend and have a general cleanout.

The strange thing is though that with the car going at speed and the vents open I get minimal air coming in. If I open a window (even just slightly) the vents start producing air at a similar pressure than they would have normally.

Is this just an air presssure thing or does it indicate anything electrical ?

I already have the usual Duo Valve issue so we are talking hot air regardless of setting.

Anyone experienced anything similar with a failing blower ?

Cheers

 

[cornerstone]

Opening the window just reduces the pressure inside the vehicle. This allows the air to flow through the heater box easier (and quicker).

 

[GP801]

If your car has a sunroof try tilting it open. Will have the same effect but less turbulence than opening the windows. Will at least let you get some heat in until its fixed.

 

[Smiley]

Probably the motor or the brushes (or both) are on their way out. In my experience it is a waste of time buying a second hand unit - they are all getting old now and units at breakers may have also been out in the elements at some point.
Problem is that a new complete assembly from MB is close to £300. The cheaper alternatives from GSF (for example) are a complete unknown brand (I tried googling the name and nothing came back) so the approx £150 may not be a good investment. I ended up buying a new bare Bosch motor from a Bosch agent for about £90 and it was a good move. I now have a 124 with a quiet and efficient blower just like a new car
Stripping out and replacing the blower motor is a couple of hour job so not something to be repeating over and over again.
Whilst you have the wiper assembly out give it a lube.

 

[shanksy]

Man that was cold this morning
I had that horrible dilemma where I couldn't clear my windscreen without air yet couldnt get air without driving.

Thanks for the tips, will try the sunroof instead tomorrow and will see what I can find at the weekend.
If its £300 for a new Merc unit its pricey but I think I would pay it in this weather.
Cheers
Lee

 

[Smiley]

You can achieve the same result by buying just the motor from Bosch. Remove the blower motor from the car and carefully remove the squirrel cage (the fan bit) by supporting it and tapping the centre of the motor out of the cage (after removing the black plastic shroud - held on with one screw). Get the Bosch part number off the motor and order a new one from your local Bosch distributor. Should be less than £100. Refit the squirrel cage (easy push fit) put the black plastic surround back on and you will then (effectivley) have a brand new blower motor and you will have saved £200.

 

[shanksy]

Cheers Smiley i'll give that a go then if not too difficult. Did you replace the brushes as well ? If so do you have to get from Dealer or any cheap options. Is it easy to tell once opened whether its the motor or brushes ?

 

[Smiley]

The new motor is a complete new unit with new brushes the whole lot. It is a relatively straightforward job to swap the old motor and the new motor once the whole blower assembly has been removed from the car.
You can look at the length of the brushes and it may be the problem. You can not buy them from MB. The replacement of the brushes is a bit more involved as it means unsoldering and resoldering the connections and one of them is not easy to get at. On top of that the rest of the motor and bearings WILL be worn after 15 ish years - so I decided that the best long term solution was replace the motor and forget about it for another 15 years