Hi everyone... I have a 1999 S420 and have been having issues with my blower. finally quit working. My dealer said it was a bad blower and regulator, a $1300 fix. So i bought a new regulator and salvage blower motor and put it in myself. When I started the car the auto temp gage was on auto and blower was blowing full speed, Great! when i manually tried to turn down the fan it turned off. then when I turned it on and off it worked at full speed but then would turn on and off. Is there something i need to program here. Any help would be appreciated! I would really like to figure this out.

kowalik@tds.net

 

You need to check the control voltage to the regulator. With min blower selected, should have < 0.5V. With blower on max should have > 7V.If you have anything other than that the a/c panel or very unlikely wiring faulty.