Background: I had to remove the mechanical fan from my 82 US to accommodate the supercharger. I installed two SPAL pullers, spliced them into the electrical AC fan, and jumped the thermostat so that all three ran as soon as the key was turned. I realized this was overkill, as almost all of my driving is on the highway, and with no AC in the car, most of the time I don't need a fan running at all.

The plan: I bought an aftermarket fan controller. I want to wire the pullers to come on when the engine gets warm (stuck in traffic), and reconnect the AC fan to its original thermostat for back up.

The question: Where should I grab power from for the pullers? I used to take it from the AC fan, but since that won't run till it reaches higher temps, I need a new source.

Bonus question: What temp should I set the pullers to kick on?

Extra Bonus question: What size wiring looms (plastic tubes) go around the wiring in the engine bay? Mine are all cracked and ugly.

Thanks for any help,

 

if its a temp switched controller, you can run the power off the jump post.

id say set it to just above the temp of the T-stat

i hate split wire loom. i uses silicone/fiberglass weave loom. but you have to rebuild a harness and add it then.

 

Thanks, Jake.
If I run it off of the jump post, will the fans run with car off?
I'm slightly concerned about running out of juice for the next start.

 

it all depends on the controller you have. most aftermarket controllers will turn the fans on at say, 180 then off at 170.
Like mine run a little when the car is off, but only till the temp drops. then off they go.

 

Ok, that makes sense to me. Thanks again.

Anybody know the wiring looms sizes? I'm not yet ready to rebuild my harnesses.

 

Wirecare stocks the velcro closure wiring loom, they also have the woven split tube which works well for installing in-situation, and both can be reused when you rebuild the harness later.

 

^^^^ thats good stuff too!

 

Porsche took the trouble of supplying fan power directly from the battery for S4+ cars with factory dual fans. Were I fitting full-capacity electrics to an early car, I'd connect to the positive battery terminal at the starter end. Or more likely, fit new up-rated wiring between the jump post, alternator, and starter terminals, with fans relays at the jump post. Reality is that most early 928'a have FOE (Front of Engine)harnesses that have deteriorated a lot, so adding new positive power feeds to replace the original in-harness conductors makes a whole lot of electrical sense, IMHO anyway.

 

I have 2 x 11" SPAL fans on mine, with the temp sensor in the top hose. This is a 98/93C (208/199F) switch, and this keeps the temp max to the second white line. I tried several other temp settings , and found that a 92/87C switch had the fans on all the time in suburban stop/start driving. I put the switch in the top hose because I found the fans running behaviour using the std bottom front switch did not track well with the temp gauge. I am running one fan off the std a/c fan relay, and triggering the other fan off the first via a separate relay fed by the hot post. On one test run with this set up I was checking on the fuse board and found the std fan relay VERY hot (original unit), so I replaced it - relays do wear out!

jp 83 Euro S AT 55k

 

I replaced my belt driven fan with the dual F
Mercury Mystique set up and added a Hayden dual fan controller. Each fan is controlled separately by its own relay so you have single fan at what ever temp you want and then second fan 10 deg later.

http://www.haydenauto.com/New%20Prod...r/Content.aspx

 

So, the controller has a line for constant 12V, which I'm running of the the jump post. It also has a line for ignition power to the relay. I know I could just splice into the constant line and have it run with the car off. I think I would prefer to have it turn off with the car.
Anybody have a good idea for a line to tap into, under the hood, that has power only when the car is on, but always when the car is on?
Thanks.

 

Anybody got an idea where I can grab 12v, under the hood, that's on when the car is on?

 

a switched 12v under the hood? hummmmmm good question.

 

Don't forget to add a suitable fuse for your fan system.....

 

Fuse is built in with the controller.