My son just got an '86 300e and the blower motor is not functioning. It does not appear to have the fuse upgrade (or at least we cannot find it if it does) and the blower motor is not getting the 12 volt signal. After removing and checking the motor we did some more diagnostics and I find that the plug behind the brake booster does not have 12v on the red lead. The yellow lead ranges from 1 - 6 volts when the fan switch is adjusted. Black lead appears to be ground and is ok. If I put 12 to the red lead the fan works correctly. Now my question.

Where does the red lead on this plug get the 12v from? Could this be due to a blown fuse (if not obviously)? After checking both sides of fuse 12 in the fuse box there is no power there whatsover and it looks a little melted on the bottom side. How would I go about getting the 12 volts from the fuse box to the red lead? Can I just get an inline fuse (30 amp) and do the upgrade myself without a MB kit? How do you get into the fuse box to get the power? I have tried loosening the 6 screws I see for the fuse box and cover and it will not open. We have the repairs CD's but they are not helping with my limited electrical knowledge.

Thanks to any and all who can help. This is his first car and he cannot drive it unless he gets some heat. I am sure you all have felt the same as him about wanting to drive the car you just bought. Thanks again in advance.