[R129 SL] AC quit; fuse?

[Jan Kuylaars]

In the past some times i discovered that the blower motor wont not
operate. Then turning on again the switch solved the problem.

Yesterday the motor did not operate at all. Turning several time the
switch did not change anything.

So I must repair the system. Because all the other functions on the half
automatic climate control were normal operating , 

I could hear the air-operated valves close  when I set the blower switch
on off and open when I used forced windshield heating on 6 , 

I now for 99% that the control box was not defective.

Looking on the ETM ( electronic trouble manual) on the MB USA DVD I
could see that there were four other parts that could be defect.

1-The Fuse F19 , placed near the big fuse box , above the brake vacuum
box. 

2-N29, the power control unit, placed on the blower motor.

3-The blower motor M2 , placed underneath the air inlet filter.

4- The wiring in this system, including the earth connection W1, placed
under the dashboard.

Off course I hoped that the last was not the issue.

 

So I started with taking away the rubber band that is positioned between
the air inlet and the motor compartment.

Then pulling the grey cap what is positioned between the windshield
wiper and the mechanic up from the wiper system.

Unscrew the bolt that holds the wiper arm on the system , and take of
the wiper arm by pulling it to the right.

Unscrew the left and right air inlet box by not taking out the screw,
but only loose them some turns. |For the inner screws near the wiper
Motor it is necessary to putt the screwdriver true the hole that is
covered by plastic taps. The hole looks like a cross.

After unscrew pull the outside ( mirror side ) up towards the roof for
some inches. The box becomes loose from the screws.

Then pull the right one to the right mirror side and the left to the
left mirror side. Because all the holes are on one side open, 

you can now takeoff the boxes from the chassis.

 

Then unscrew the two bolts from the dust filter compartment , unclip the
three clips on the motor side and pull off the complete filter house
cover.

Take out the sensor on the right side , careful take out the wiring and
lay the sensor on the motor air filter.

Unscrew all the Philips screws on the left computer compartment cover
plate and take off the cover plate.

Carefully take out the wire from the sensor that you lay down on the
motor air filter to the computer compartment.

The wire is positioned between the bottom from the airfilter compartment
and the chassis .

Pull out the green and yellow air pipes out off the connectors in the
computer compartment.

Pull out the round cover plate underneath the rubber from the wiper
mechanism.

Unscrew the left wiper motor cover plate  and the right air inlet cover
plate , they are fastened with two Philips screws and two plastic
fasteners.

Take off these covers.

 

Now you can see the complete wiper system. Search for the wiper computer
positioned to the windshield side in the computer compartment.

On top of the computer there is a smaller relay box. on these relay box
there is the wiper motor connector. You can see it on the colours and
the thickness 


>From the wires : on the right side it is green-white-black-yellow and

brown. The same like on the wiper motor. You also can follow the cable
from the wiper motor to the relay box. Push the holder from the
connector to the left so the connector come off the relay box.

 

Now unscrew the two bolts which clamped this cable on the wiper motor.
Unsolder or un well the wires on the wiper motor. Started with the green
from the motor

And the cable, then the red from the motor and white from the cable,
then the black-yellow and brown. On the brown there is also an small
brown wire to the shell for earth

Pull the cable out off the compartment to the computer compartment. Be
aware not to damage the rubber seal so you can later putt it back
perfectly watertight.

Unscrew the under rubber holder from the wiper mechanism with a small 90
degrees wrench set.  Unscrew the rest from the mechanism with a 10 mm
pipe tool set.

Take out the wiper mechanism to pull it to wards the motor compartment.

 

Unscrew the left rubber mounting  from the wiper mechanism with a 22 mm
wrench set. Unscrew the other bolts with a 10 mm pipe tool out of the
bottom of the 

Air filter compartment. Then use a 10 mm pipe tool that is at least 20cm
long and putt some chewing gum or other adhesive compound at the end.

That is that the bolts are not falling into the chassis but stay in the
tool to take them out of the car.

There are three bolts positioned in the bottom from the air filter
compartment between the iron chassis from the motor compartment and  the
plastic side wall


>From the air filter compartment. So you have only a half inch to do so.

Also the four other cables laying in this space can be a problem.

You can solve this problem by using a big flat screwdriver and pull one
cable to the air filter compartment, so you can use the pipe tool
between the cables.

( when you assemble you have no problem because then you have  the
possibility and space to lay all the cable's neat above each other to
the iron side  )

Now pull out the complete air filter bottom out of the car.

 

Now you can see the blower motor. Take off the green air pipe from the
motor . Take of the red and green wires from the motor.

Unclip the four clips on the right side from the vent cover, and two
clips from the left vent cover. Unclip the steel band what is holding
the blower motor on its place.

Now you can take of the motor complete with vents. 

 

I tried to let the motor turn by hand, but it was very difficult. The
bearings were completely dried out. Checking the cowl browsers ; they
were OK.

Putting some oil on the bearings , and turning the motor by hand , loose
the bearings . Using an extern power supply from 12 volts 5 Amps let the
motor

Turning faster and faster , and after some time and repeating the oil ,
the motor turns like new.

 

So after assembling the complete system in reverse order like mentioned
above, I repaired my car with five drips of oil and four ours of  my own
labour.

Dissembling take 3 hours and assembling only one hour. That's because I
then new how to work. That's why I write it down for those people who
must do the same job.

At the same time I oiled the wiper system, let come out the arm by
turning the motor.

 

 

Friendly greetings from The Flying Dutchmen 500 SL 

 

-----Oorspronkelijk bericht-----
Van: r129list-bounces at mbcoupes.com
[mailto:r129list-bounces at mbcoupes.com] Namens Paul Samarin
Verzonden: vrijdag 27 juni 2008 3:10
Aan: SL Mailing List
Onderwerp: Re: [R129 SL] AC quit; fuse?


The archives are very difficult to search.  You gotta go month by month,
unless I'm looking at it wrong.  Do you have any idea what month and
year you might have posted on this? 

Thanks,

Paul

On Jun 26, 2008, at 5:57 PM, Jan Kuylaars wrote:


Paul.
I am thinking your blower motor bearings are become dry. SO there is
power on the motor, only it is not turning.
I had the same and had take out the blower , give some oil on the
bearings, turned the blower some turns by hand till it starts to work.
I  have already posted a message on this board how to dissemble the
blower motor, so look into the stored messages.
 
beside there is a electronic fuse/switch on the motor itself
Flying Dutchmen.
 

-----Oorspronkelijk bericht-----
Van: r129list-bounces at mbcoupes.com
[mailto:r129list-bounces at mbcoupes.com] Namens Paul Samarin
Verzonden: donderdag 26 juni 2008 23:12
Aan: mercedes at mercedeslist.com; Mercedes Mailing Lists Coupes; SL
Mailing List
Onderwerp: [R129 SL] AC quit; fuse?


While driving my 1990 500 SL (R129) with the AC blowing cold and
everything right with the world, the fan simply stopped blowing.  On my
former 1986 560 SEC this meant a large fuse outside the fuse box mounted
to the cabin-side of the engine bay wall.  I don't see a similar fuse on
my R129, and all of the fuses in the fuse box appear fine. 

Is there another fuse somewhere for the AC blower?

Thanks,



Paul Samarin
pauls at sbcglobal.net
Sweating in So. Cal.




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Paul Samarin
pauls at sbcglobal.net




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