taurus fan install question...

[American_Muscle]

I got my relay in the mail today.I'll be hooking it up tomorrow.
I'll be controlling the fan with a toggle switch.

I have a few questions...

1) I was told to make the switch a "ground switch", ie make the switch "close" the ground connection instead of having 12V in the cabin if you make it a 12V switch.
If I do this don't I need to connect the switch to Pole 85 on the Bosch relay instead of 86 like in this diagram? http://forums.stangnet.com/attachment.php?attachmentid=18796

If do this, where does Pole 86 go?
To a 12V source? Which one?Battery?
So 30 AND 86 would both go to the battery?
Doesn't make much sense to me,...

2) The only diode I need is at the fan motor right?(if it doesn't already have a diode built in.)

Thanks
Patrick

 

[TheUser]

ok man, let me see if I can help you out. I'm no expert w/ relays and what not, but I have read about them and used them somewhat.

You are correct, I believe, in that if you use a "ground switch," you would hook the ground to the "ground "side of the relay or pole 85. Pole 86 would go to the battery as you suggested. Basically, what you're doing is you're creating a magnetic charge when you flip the switch; when you flip your ground switch, you will complete the ground circuit, which will energize the magnet since it already has a "hot 12v" charge from the battery. The magnetic charge will pull the little door down between poles 30 and 87 and close that connection, which will turn your fan on by "relaying" the 12v battery charge to the fan.

So, yes, you will want 30 and 86 to both go to the battery. 86 will engergize the magnet and 30 will power the fan once the little "door" closes.

I hope this helps and if any part of it is wrong, someone correct me.

 

[American_Muscle]

Yeah that's what I figured.

Just wanted to make sure before I burn the car down....

BTW...I only need to put a fuse in the wire going from polo 30 to the battery right.
Not the other one since it won't pull as much.

Which fuse should I go for?
I remember reading 30 or 35 amps?

 

[HISSIN50]

Correct about using 85 for switching ground, vs 86 if you were switching 12 volts.

Note that you cant switch the relay coils on that relay like you can on smaller relays. I know you arent, but it was worth mentioning for future searchers since people are not strict about convention when wiring up relays.

If you use the battery for 86 (the 12 volt coil-trigger), then the fan can stay on at all times. I prefer to use a key-on hot source for the trigger, but definately use fused battery power for the common (30) terminal.

If you are not using a controller, 86 just goes to the switch. If using a controller, it goes to the temp switch and you tee your ground wire from the switch into it too (or use the dedicated port on the controller for a switch, if it has one). I would use a blocking diode on the controller ground pulse if teeing a switched ground into that wire, though it probably does not matter a whole lot.

The flyback diode (freewheeling diode) goes across the motor and other than the possible blocking diode (avl from Radio Shack), I dont see the need for any diodes (the blocking one is really not necessary, but cant hurt).

For fuses, here is my take: you cant have too many. Guys in here know I use a lot of them - if a wire chafes, pack rats eat it, etc, it is nice to have the protection. If a circuit functions properly, you can have 20 fuses in series and none will ever blow. SHould an issue arise, it is nice to have the fuses.

Fuse the battery power for sure. I would fuse the 12 volt switching wire (86) for fun too - just in case of a short.

I would also tell you not to have high and low speed switched on at the same time - always have one switch on and one off.

Good luck.

 

[American_Muscle]

Very informative post!
Thanks that cleared up a lot.

Also, concerning 86 (12v coil trigger)...I've read that it's not good to use the battery as the source because it will pull nearly as much as the 12v wire powering the fan motor...eventually burning the relay.

What can I use?Cigarette lighter? Should I just tap into that wire?

Also, do I need the diode even if I don't use the LED in that diagram?
What does it do?

Also, I just notuced my relay is part number 0 332 002 160.

I know the bosch relay 0 332 002 156 was suggested.

What's different about mine?

It has the same connnections and same connnecting numbers and it's also 12V/75A.

 

[HISSIN50]

Very informative post!
Thanks that cleared up a lot.

Also, concerning 86 (12v coil trigger)...I've read that it's not good to use the battery as the source because it will pull nearly as much as the 12v wire powering the fan motor...eventually burning the relay.

What can I use?Cigarette lighter? Should I just tap into that wire?

Also, do I need the diode even if I don't use the LED in that diagram?
What does it do?

Also, I just notuced my relay is part number 0 332 002 160.

I know the bosch relay 0 332 002 156 was suggested.

What's different about mine?

It has the same connnections and same connnecting numbers and it's also 12V/75A.

I am not sure of the source for the first statement about the relay coil draw (terminal 86). It should draw a bit less than one amp, even if you had a power plant hooked up to it. The relay only draws what it needs to actuate, no more. I would use something simple - some guys use the coolant overflow power wire. The positive wire on the coil would work too.

The freewheeling diode is for when the fan stops being powered, yet is still spinning (effectively, as a generator). It is necessary no matter what IMHO. THe LED's often use a resistor but that is totally different.

There have been a couple of relays used for the different fans (one Taurus write up recommended one Bosch relay and a Mark VIII article recommended another). I would do an internet search on yours and see its rating (I cant remember the good site with the Bosch relays, to look it up for you).

Good luck.

 

[American_Muscle]

Hissin50:

I sent you a PM about the diode.

Oh and I ordered the right relay now.

I got the other one because it was cheap but it turns out it's not listed on that bosch relay site. (power relays)

 

[HISSIN50]

And I just replied.