Question about wiring in the diode for an e-fan install?

[Fett]

I know that I am most likely over-thinking this one, but I am not 100% sure how to wire in the diode. I picked it up tonight and am going to wire the fan tomorrow...using the VW switch setup. I am trying to just map everything out prior, and I know WHERE the diode goes...I just don't know how. If anybody has a picture or a good explaination that a moron (like myself) can follow, that would be great.

Do I just tape a wire into both the + and - fan wire, cut that wire, and splice in the diode? Or is there a more "technical" way of doing it?

Also, for the in-line fuse...what should I go with? 40 amp? 30amp...higher, lower?

 

[GreatWhite]

Don't need a real big fuselink, just a higher capacity Relay, like at least 75amp.

 

[Fett]

Yea, I am using a 70amp Ford relay. I just noticed that in the VW switch diagram it also shows a fuselink.

Also....and this might sound really stupid....

Is there a specific direction that the diode needs to go? Or does it matter which end I wire to the + and which end to the -?

 

[HISSIN50]

There is an anode and cathode side to the flyback diode. Direction absolutely matters.

Using something similar to a 1N5404. I'd want the cathode (striped) side on same side as the fan + wire.

Now PLEASE wait for one of the electrical guys to confirm this - it's been a LONG time since I messed with freewheeling diodes.

Good luck.

 

[jrichker]

There is an anode and cathode side to the flyback diode. Direction absolutely matters.

Using something similar to a 1N5404. I'd want the cathode (striped) side on same side as the fan + wire.

Now PLEASE wait for one of the electrical guys to confirm this - it's been a LONG time since I messed with freewheeling diodes.

Good luck.

Hissin50 is correct. When using a diode as a clamp, the cathode goes to the + (positive) side. This provides the electrical energy stored in the fan's windings a path to dissipate.

 

[Fett]

Unfortunatly the diodes I got from Radio Shack didn't have the mark on them....actually they did, but the mark was "sideways". I tested resistance with an ohm meter and figured out which way it will allow current...but I didn't wire them in yet. I will do that next weekend.