[Julian0922]

Hi, I did not find an answer after searching for a bit, so I have to open a topic and hope somebody can give me at least a hint:

I own a 1990 300e and the blower fan ONLY works when the car is shut off, as soon as I start the car the fan stops running....

What might be the cause? Battery, the ghost in the machine or...:surrender:? A shortage I would exclude, because otherwise it would do it only sometimes, but it does it EVERY time...and with that I mean hundreds of times. Just that in the autumn and winter a working fan is necessary up here...(WA)

Thanks in advance for the help.... :bowdown:

 

[macdrone]

I would look at the ignition wire harness side as the issue. If you pull the tumbler and turn it and the issue isnt there then someone may have changed something as no power should be to it with ignition off. Some people run hot wires and a switch to the motor to bypass the the CCU (climate control unit) and same with the A/C compressor. That way they can have full fan or full AC or both without all the systems safeties shutting it down.

Good Luck.

 

[Julian0922]

Sorry but obviously there was a little misunderstanding MacDrone...I have meant of course that the blower/fan ONLY runs when the ignition is in position 2. (Since that is also an issue because some may say its position 1: ONLY when the ignition lights are all on).

Thanks for your quick response though!

 

[cbc atl]

I believe macdrone knows what your problem is and has the solution based on your first post. It's probably the tumbler aka ignition/starter switch; although, it could be the wiring going to the switch.

And now of course there may simply be too little power to run it. When the car is running what do you have for volts on the battery? It should be minimum 13.2 volts and not exceeding 14.2 volts.

That circuit is hot in run. That means that when you start the car and let go of the key then the circuit should be hot. That happens to be the same position you say the blower works now except it only works there before you turn it all the way to start. So that is why it seems to be the switch (or the wiring to the switch).

The hot wire goes from the ignition switch to the fuse box and when the ignition/starter switch is turned to the correct position it makes the circuit hot. It's probably the tumbler aka ignition/starter switch.

And it is a pretty simple circuit comparatively speaking; there is the fuse, a ground W1, a connector, the blower control unit and the fresh/recirculate air switch S24: ACC Power Distribution

W1 Main ground (behind instrument cluster) Behind left side of instrument cluster 235-5

X64 Connector, blower speed control/interior harness Above and rearward of brake booster

S24 Fresh/recirculated air switch Center console, above radio

 

[augapfel]

Quote: I own a 1990 300e and the blower fan ONLY works when the car is shut off, as soon as I start the car the fan stops running....

Do you mean that the blower fan runs only when the *engine* is off but the key is in run and then stops running when you start the engine?

 

[Julian0922]

Exactly Augapfel, my english might be a bit complicated...in der Sprache in der "Augapfel" etwas bedeutet waere das viel viel einfacher....

But I will go with the advice from CBC Atl., especially since he mentioned the voltage! I work currently too long to get the battery checked..and if its NOT the battery I am screwed I guess.
(BTW, fuse (fusible link) from the AC/heater is ok...)