DOn't be scared, it's the blower motor regulator. This is a very common problem on the early 140's. I replaced mine about a month ago. Order the part on benzbin.com and you can install it yourself. Just simply remove the cowl cover (about 5 screws) and you will see the blower motor regulator screwd on top of the blower assembly. Simply remove and replace, it should blow like brand new!

P.S. While under there you might want to replace the cabin air filter...