Cadillac Repair: wiring a new circuit from the battery to the heater fan, inline fuse, cadillac deville

Question
QUESTION: How can I run a circuit directly from the battery to the heater blower motor and use a toggle switch to run it from inside the car.  The motor works but I have some electrical problems in that circuit that i want to by pass to save money.  I also have cut the two wires going from the motor so that I could tie into them at the motor with a new circuit to prevent current from going back through the dash electrical components under the glovebox.  I have a 1990 cadillac deville.  I know that it should be able to be done; that is, creating an entirely new circuit.  Woul I need to use some component to lower the voltage down from 12 volts.  I have already boughten and inline fuse with a 30 amperage spade fuse.  Would I wire that near to the battery and also would the negative top post be a sufficient groung for the new circuit or would I need to create another.  The electrical system for the rest of the car starts of the side posts of the battery.  Thank you for you time.  Greg Burdette

ANSWER: why don'tou just fix the problem with the fan circuitry ?.

What IS the problem with the fan ?>

---------- FOLLOW-UP ----------

QUESTION: again, I want to ask the same question and would like an answer if you know how to give one.  The fan works and I want to create a circuit from the battery with a toggle switch and want to know also if the motor can run off 12 volts with no problems or not.  I think that the question is precise, now I am hoping that you could be the same.  Greg Burdette

Answer
Since the blower motor operates in a voltage range of 2 volts up to 16 volts, Applying battery volts will run the fan speed at whatever battery voltage your electrical system is putting out at a specific time whih would be anywhere from 13.8 to 14.2 volts  and you would only have basically ONE fan speed with a little variance  of fan speed due to the charging system fluctuations.

You may also be seeing the CHECK ENGINE light illuminated on the dash at ALL TIMES.