Hi CG, The first thing that I would want to know is, how many amps does the fan use? I want to say that you definately must put this fan on a fuse, and I also think that you definately want it on its own individual, manual, on/off switch. Many fans that I have read about can pull some high amps but here's the rule, if the device does not pull more amps than the amp rating of the on/off switch you are going to use, then you don't need a relay. The switch can turn it on and off, you don't need to step it down , around or thru anything just let the single pole switch do what it is designed to do.
The next point is what are you going to hook it too? If this fan pulls some high amps such as 20 amps, then you don't want to hook it to just any wire on the Healey wiring harness because you will easily be exceeding the rating of that particular wire especially when combined with whatever else is on that wire. Most the wiring in a Healey is sized just right for what it was originally intended to supply, it has almost no capacity for additional amps. Just for conversation sake, if you over load a wire, it will at the very least run hot (fire hazzard), it will also cause a voltage drop out to the devise you are trying to supply, the lower voltage out at the devise will cause the devise to try to pull even more amps and the devise will be damaged.
So, as stated in an early post, the hot terminal of the battery wire at the starter solenoid is about the only location where the supply wire (large wire coming from the battery) is large enough to supply some relatively, extra, high amps for a device such as a cooling fan. I would use size number 12 stranded wire because it is rated at 20 amps. You will quickly notice that it is larger than most the wire in a Healey. You will have to crimp a large eye connector unto this wire to put it on the large terminal of the solenoid. Make sure you get it on the wire coming from the battery. Then you will have to immediately go to an In Line Fuse Holder. I can't think of any reason why you would need a slow blow fuse. If this thing decides it wants to pull more than the fused rating (a short in the circuit or an jammed fan blade) I believe I would want it to blow the fuse as fast as possible instead of sticking around long enough to create more heat in the circuit. Since you are not pulling the circuit from wires that come thru the original fuses you will need this fuse holder. Then run the #12 wire from the fuse holder to either directly to an on/off switch or to a relay, which ever you decide. Size the fuse as what is stated on the fan name tag or as what the manufacturer says it needs, or maybe just a tesch higher. If the fan is labeled as in Watts instead of Amps then you can figure out the amps with this formula: Amps = Watts divided by Volts. Volts being 12. Good Luck.
Hi Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
'
