Renok7

I own a '93 300E 4 matic. With the ignition key on instruments the high fan setting works normally. However, when the car is running, the high fan setting won't work. My mechanic thinks that the blower motor regulator switch is defective but he isn't sure since the high fan setting works normally when the car in not running (i.e. instruments only). Before that he had replaced the ignition switch and tried a new push button control but to no avail. Any input would be greatly appreciated.

Thanks

mbtech208

I haven't ever seen the high setting work when the engine is off, and then stop working when the engine is running. In all circumstances where the high setting doesn't work and every other fan setting works, the defective part is the blower regulator. I can't explain why the high setting works with the car off, but I'd be willing to bet the regulator is bad.

Renok7

Thanks MBTech,

I'm afraid that I will have to replace my regulator.

Reno