I have an 89 300se. I have had the car about a year and the air/heat has always blown, but not blown very hard. Last fall, I had the brushes replaced and at that time the armature looked fine. The mechanic admitted that the fan did not blow really as hard as it should have. We never dug into it to resolve. I have since purchased my second benz(420sel) and had to replace the blower motor because it was completely worn out. The fan on the 420 blows about 3-4 times as hard as my 300. Could the armature be worse than expected or could the blower motor itself just be worn out? Any help would be appreciated. Thanks. Scott

Seems like you have to dive into the blower controller and check voltages.

You might try swapping blower assemblies (a few screws) and if anything changes.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

Could the armature be worse than expected or could the blower motor itself just be worn out?
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Another possible cause is that the contacts behind your dash control fan button/s may not be making good contact. I am pretty sure you can take the dash unit out and clean and/or re-solder the contacts. Or if that is the problem you can replace the entire unit but that is expensive.