General electrical question

[dmention7]

I'm rewiring my LA-IC fan and pump, and I'm just wondering if there's a "proper" or best practice way to do this.

ATM, both accessories are powered off a relay that's switched from the interior. I want this to only possibly be on when accessory power is on, so that I don't have to switch it on and off every time I drive. Would I be best off supplying constant power to the relay and accessory power to the switch, or vice versa? I suspect the first way, but I'm not 100% sure...

 

[DrWebster]

Why do you have the switch to begin with? You should be able to get the relay to draw power from a constant feed (e.g. direct from the battery) only when power is sensed from the accessory line (e.g. when the car is on). What you're doing is actually pretty analogous to using a relay harness with HID's.

 

[dmention7]

It actually is a relay harness from an HID kit. lol But then, most higher draw switches just trigger a relay.

And the reason I want a switch is so that I can turn the fan/pump off if I want, or so they don't drain the battery if I don't need them on. Exactly the same reasons you'd want any other accessory to be switched.

 

[DrWebster]

Well, then I'd wire the switch to the constant power side of the relay.

 

[Grappler]

http://www.aaroncake.net/rx-7/efaninstall.htm (look at the 3rd diagram)

easiest way I know how

I grabbed a painless efan harness so I can turn on the fan when the A/c (that I don't have) is on.

 

[Big Nate]

Jay if you wanted to be super baller you would wire your fan to a heat sensor so it would only turn on when the car reaches XXX°. That looks like a great link for the thread.

 

[dmention7]

This is how I currently have it installed, minus the t-stat, and the fan and pump are both wired in parallel off the relay (main reason I am rewiring it). So it sounds like I did it mostly correct the first time. But yes, a tstat fan controller would probably be a good idea. Do they go down as low as 100F?

 

[Big Nate]

Why would you want you fan on if it is that low?

My truck has belt driven fan on it but the new 2010 + models all got electric. I am going to be doing a full swap when I get the time and money. So this thread is very relevant to my interest.

 

[dmention7]

This is for the LA-IC setup in my car. I want the coolant to be as close to ambient as possible, but I'm certain that at freeway speeds the fan isn't doing a thing.

 

[Grappler]

The lowest I have seen turns on at 150 and off at 170... I don't really see why you would switch it you probably aren't losing much by having it on all the time.