Rocket,
Below is a link that tells how to replace the blower motor. Under the blower motor is the regulator you are looking for. It is pretty easy to replace and you should be able to find a used one on ebay for a good price. I just recently did mine which is a 1994 E320 which is just slightly different from the tutorial. If you need any info just PM me and I will try to help you more. Be very careful when moving the wires from the wire harness around especially if it was made between the years 91-96, brittle casing to the wires. As I have found out.
http://www.peachparts.com/Wikka/W124BlowerMotor