I have a 1998 merceded s320 and the blower has stopped working (i get air through the defrost but thats it...I do not have a service manual and have no idea where to start to figure out what the problem could be ...any help is greatly appreciated ~~Marion~~

What do you mean, that you get air through the defrost? The blower only blows in defrost mode? If it's just airflow while moving, then the blower might indeed be dead. If you get airflow while not moving, then the blower is doing something - In that case it maybe dying, or there is a problem with the pushbutton control, or the blower motor regulator.
First and foremost, the first thing to do, is to check all of the fuses - wiggle them around, and examine with a fine toothed comb....hairline fractures often go unnoticed.

Good luck!

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

Sounds like a bad blower regulator if it only works in defrost. Do you get air in other settings if you set the fan switch to max?

The blower regulator is beside the blower itself, under the hood -

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=28G13A2TU28G13AB1Z&year=1998&make=MB&model=S-320-001&category=R&part=Blower+Regulator

Sixto
87 300D

You are right ..the air only passes through defrost when the vehicle is moving...the blower doesn't blow in any setting...someone had mentioned a resistor?? Anyone have any idea where that is located?Is the blower under the hood? Also,anyone know where I might be able to purchase a service manual?

Chexck the fuse box map.........sounds like you have a bad feed fuse.

I was happy with the www.alldatadiy.com subscription I used with the 95 S420 and 93 300SD. Covered everything I needed it to cover.

To get to the blower motor, set the hood to vertical position, remove 6-7 screws holding the plastic panel between the engine and firewall. They're big screws that take a Philips screwdriver. Lift the panel to see what hoses have to be removed. There are green and red hoses to disconnect along the passenger side and some sort of heater hose to move aside on the driver side. Remove the panel. This will expose the blower main filter screen. It's about a square foot so you won't miss its size. Remove the filter to expose the blower motor assembly.

You should see the two big spade connectors into the motor core. Disconnect them and test. One is +12V all the time so be careful. You can use these connectors to test the motor core. If the motor works and there's +12V to one of the wires, the regulator is bad.

The blower motor assembly is held by 4 Torx screws. The one in the aft passenger side corner can easily fall into an abyss. The regulator is held by 2 Torx screws onto the top blower casing. You should renew the heat transfer paste when you touch it.

Sixto
87 300D