1995 Mercedes Benz 420sl • 223,000 miles

1. Suddenly I am not getting any air inside the car. We tested the blower its working we test it threw connecting it to direct electricity but from inside the car threw the panel nothing happens. You can hear that it changes air flow positions but no air.

2. The other problem is the central lock system stop working, if you press the key you get red light the car wont work you press it again you get green light and the car starts but the doors wont lock or open you have to do it manually and the 2 antenas in the back stop working and the fuel lock also
September 22, 2011.

If you have a 12 volt supply and the fan does not work at all, the motor is bad. It needs to be replaced.

The central lock problem and other systems might be due to a malfunctioning Anti-Theft Alarm Control Unit. It is located behind the right front footrest.
It is tied into the starter lockout, door locks and the radio which has a module to power the antennas.
I traced the problems all to this one circuit they all share common to the anti-thefet unit. You might check the ground for the unit, but more then likely it is failing.
Sometimes if the battery gets low or for other reasons, the key fob programming can change. Some key fobs can be programmed at a dealership to have slightly different functions. However you may not have that option and it is less likley to be the issue. But, I wanted you to have all the information and ideas I could think of.
Take care.

Thank you for your time, but the fan works when supplied with a 12v directly

Sep 22, 2011.
I am sorry I did not see you had already done an isolation test on the motor. I was a little tired when I read it.

Here is the description of the blower motor circuit so you can back probe and see where the 12 volts is lost.

Bothe wires from the motor go to an Electronic Blower Control box which is in the rear of the engine compartment.

One wire goes into the number 4 connection.

The next wire at the number 3 connection is white and pink. It goes to the Pushbutton Control Unit.

The number 2 connection shares 2 wires. One from the blower motor and a black and green wire which goes to the climate control auxiliary fuse. This is a 30 Amp fuse located at the left side of the component compartment. It comes out of the fuse with a pink and green wire to Ignition Run Position of the ignition switch.

The last wire at the number 1 connection is brown and goes to ground. It is located behind the left side of the instrument cluster.

I hope this helps. I cannot paste in the diagram due to copyright/ownership rules.

Thank you I will come back with the results over the weekend

Sep 23, 2011.