Last Fall, I had the blower fan on my 1995 E300 replaced. At the time, the mechanic recommended replacing both the fan and the control unit. The fan seemed to come on when it wanted, and sometimes not at all. I opted to have the fan, which was the more difficult part to install, replaced. After the fan was replaced everything worked. I am now experiencing the same problem I had last year. I just installed a new climate control unit, which was very easy to do in about 15 minutes, but the fan still does not work. What else needs to be checked or replaced for the fan to start working? My original fan lasted 12 years so I do not think the new fan has gone bad. It came on every once in a while before I replaced the control unit, and when I press a button for the AC, I can feel it kick in, but the fan does not blow.It does not blow with the heat on either. I am somewhat "mechanically and electronically challenged," so to speak, but I can follow simple instructions.

 

Some things you can check. Get a meter or test light. Find where the fan control unit plugs in and unplug it (its behind the brake vacum buster on my E320). You should have 3 conections on the body plug one of them should have power around 12 volts when the ignition is on, one isthe groundand shows 0 volts,the other goes to the climate control unit inside the car and with the fan on high should be around 9 volts and as low as 1 volt at other settings.
If you have no 12 volt power check fuses.My E320 has an extra strip fuse located in a little black box about 1.5" X .75" located by the strut on the drivers side. Im not sure about yours.
If you can't find the problem there your going to have to get to the blower motor inside its housing. Once inside its an easy check. Unplug the blower from the control unit inside add 12 volts & a ground. If it runs its not the motor its the fan control unit inside with it.
Let me know how it turns out.