I have a 99 300M, and the window for the driver side does not go down, I'm not sure what it could be, because I opened the door panel and the motor produces heat, and it doesn't look like anything is broken. Any Suggestions?

 

There could be many things that it could be. The heat could be from binding, or it could be from being worked and the regulator is broken. I would remove the regulator and see if there is a problem at the motor/regulator. Also, be very careful when working with regulators, they chop fingers easily. Where ever you can use a screw driver to move stuff around inside the door. I was just working on a car this week,key was not even in the ignition, and regulator took off squishing my pick tool. Tools are easy to replace.

 

I had a similar problem...it ended up being the switch. You can test it by removing one of the other 3 door panels and splicing into that paticular switch...if the drivers window moves then, this will confirm it is the switch...I paid like $15 ata salvage yard for my replacement.

Good Luck!