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Starting the install on my 87 Turbo left hand drive coupe. Trying to keep the interior clean and want to ditch the original A/C controls. I will not have heat or defrost, and don't need those levers. I am curious if I can rewire the blower motor to a multi-position switch? I am sure the answer is yes but as I can't find the wiring diagram for the original setup I am at a loss on what sort of switch to find and how to wire it in. I would prefer to remove the old wiring and tap right into the 4 pin connector. Is there a way to get the wiring for the blower so I can figure out how to wire a switch and also what would the load be? Can this be done with out using the original relays? 

Thank you,

Sean

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Hi Sean, the original car wiring controls the blower so all we provide is a simple on/off control. It is all in the install manual.

The new system will now use just the one fresh air fan speed slider to control the fresh air AND the A/C.  Your old system had a separate fan for A/C, hence two fan speed controls.

Keep us in the loop in your install 👍

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The blower in our system is designed to be controlled with the original fan slider from the fresh air system.   All LWB cars (‘68-) have these controls.   This is part of the original car’s wiring so does not connect to our ECU.   

If you want to delete the slider panel completely, you will still need a fan speed switch of some kind.   You would also need a way to ‘steer’ to the screen and feet provided by the other slider levers.

If you are happy to use one fan speed only, you could use the grey contact relay wire to activate a relay to switch the blower fan on.  That would then turn on when you press the button.  

 

 

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What about completely removing the factory wiring for the blower motor and wiring in a PWM speed controller with a potentiometer rotary? Can your blower motor operate through that? How many amps does your motor pull and what two wires from the 4 are the ground and high speed? Thank you for your help! 

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The blower system and Porsche wiring is low side switching.    As you look at the front of our blower unit, top left is 12V.  The other three pins are ground for each speed.   From memory, the bottom right is the high speed ground. 
 

You could use a variable motor speed controller.  It would need to be rated at 15A continuous. 
 

Generally speaking, variable speed control was avoided in automotive because of the large amount heat that needs to be ‘lost’ at low speeds.  Traditional 3 speed resistor packs get round this problem by using the fan air to cool the resistors.  
 

The 964 uses PWM for fan speed control. The heat sink is about six inches square so you can get some idea of the scale of the problem. 
 


 

 

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