Blower reg bypass?
 

I have a 94 s420 and I'm pretty sure the blower regulator is shot.
I opened up the cover and I see the blower/squirrel cage turning, just not fast enough to get the max air out of the ducts.
My question is... there a way I can test/bypass the regulator to see the fan run at full speed? I tried jumping the brown wire directly to the blue wire where the blue wire is connected to the fan but that did nothing.:confused:

The blower regulator is in the ground leg of the fan, if it spins by hand It is probably good. I stil would put a drop of ATF on the upper bearing while tou are in there

do plan to put a squirt of oil or 2.
wanted to see if there was a way of getting the blower to run on max while I wait for my new regulator

Unplug the fan motor compeletely, and run jumper wires from the battery in the car, the cigarette lighter, or from another battery. You just need to put 12 volts across the motor contacts briefly to test it. I rigged up a cigarette lighter plug from Radio Shack with about 12 ft of speaker wire so I could take it all around the car to get 12 volts to things for testing.

The power is always hot to the fan motor even with the key off (be careful when you work around it), so for this, I guess you just need to ground the ground side to the chassis. Jump a wire from the ground connector to a decent ground point, bypassing the regulator.

Brett

Brett,
when you say "put 12 volts across the motor contacts", I would put the + from the batter to the contact where the red wire currently is and the (-) to the contact where the blue wire was?

Just ground the blue wire back to the battery neg terminal..that will give you full fan and eliminate the regulator.

If it is still slow, you have a brushes/bearing problem at the motor.
I always put an ammeter in series with the jumper and take a current load test at high speed. If it draws > 25 A. , you have a motor problem. [ which will eventually burn out your new regulator]