Since I bought the car 10 years ago the PO had the fan wired into the blower motor, which was fine and stuff to get me by but crappy on hot days when i had to use my HVAC controls to run the fan while my heat was going or something. I want to get it wired back up properly if possible. ive always had to leave the fan fuse unplugged underneath my dash because if i have the fuse plugged in then my HVAC and Fan run at full high, but unplugged i can control the speed with my hvac control. The red wire in the pic seems to run directly from the radiator fan and then was tied into the purple wire at the blower motor. Im at a loss as to where its actually supposed to be ran too. If anyone can point me in the right direction thats be awesome. ignore the butt connectors in the pics, i had a mice problem come through a while ago and im trying to get everything back together from the little bastards, the fan issue predates the mouse problem. The engine I swapped in from a '91 Formula has the fan switch on the passenger head below the headers, could I use that potentially? i know its meant more for dual fans but can it work for a single fan setup?

 

That's .... uhhhh .... SODOMY.

Correct wiring would use a relay. You only need a 4-terminal one. Big fat red wire (I'd suggest #10) from the battery, as close to the + terminal as possible (usually the big stud on the starter) to terminal 30 with a fusible link (#14) at the end nearest the battery, big fat wire (#10) from terminal 87 to the + side of the motor, big fat black wire (#10 also) to ground (preferably somewhere on the engine. Small pink/blk wire from any device that has that (there are at least a dozen under the hood) to terminal 85, dark green w white strip from terminal 86 to the temp switch in the pass side head between the #6 & #8 spark plugs. That's all there is to it.

Looks like your unfortunate car's PO should be locked up for aggravated 1st degree car abuse. That's about as heinous as it gets. Should be treated as a form of domestic violence.

 

You can use that location for the fan switch, but the factory switch there was used in the dual fan setup as the secondary fan activation at 238F, much too hot for primary fan activation. What you really want for a single fan setup is a switch that activates shortly after your thermostat opens, and deactivates as your thermostat closes.

 

The factory single fan setup used a switch in the same place.

There are many switches available; all sorts of operating points.

If you use a temp that's too low, the fan will run all the time, even when it's not needed (60 miles per hour or whatever).

Best temp combo is probably one that operates (begins running the fan) at some temp, and that then closes just above thermostat temp. That way it will only run when there's actually hot water in the radiator.

Factory temps in these cars was 230ish on, 215ish off. Works fine. I'd suggest not pretending you're smarter than the factory's engineers until you understand thoroughly why they did what they did, and why what you want to do is "better" than their ideas. Which of course, could very easily happen; if it didn't, no one would ever modify anything about a car; only, to effectively modify one, you need to UNDERSTAND how it works AS IT IS, and then UNDERSTAND how whatever you want to do to it, MAKES IT BETTER. This is different from "I've always heard", or "all the fast cars at the track ...", or "I just think", or "it seems like", or "I just don't like xxx, I want yyy", or "water boils at 212° why would I ever want it to go above that", or any such amateur drivel as that. UNDERSTAND first, modify afterwards. Not everything they did was wrong.

 

I replaced the original switch in the cylinder head with one that closes at 195° and opens at 185°...

 

In the 2nd picture thats the fan relay correct? If so it appears the rest of the wires are where they need to be, its just that 1 red wire thats the rogue. Where would that one of usually been ran too? Im thinking maybe the relay was shot and they didnt realize it and just ran that wire to an easy power source?

 

What year is the wiring? Is it the 85 in your profile but with a 91 motor?


If I recall the 85 / 86 TPI cars had some sort of weird cooling fan thing that didn;t use a temp switch etc... .


if so Id by pass the stock wiring and wire in a separate cooling fan circuit and use the 91s temp switch location.

 

there's a good diagram in this thread on how to install a fan on a separate non ecm controlled circuit. I used it and used a hose temp sensor housing with a stock GM fan switch for my auxillary fan (I think only auto meter makes those.....and they are pricey). that and I also installed a separate manual override switch for emergencies and what not.... you can use the 91s temp switch location and use a stock GM fan switch as well since those are super easy to find anywhere.


Wiring Electric Fan without ECM - Third Generation F-Body Message Boards

 

I have no idea what year the wiring is from, When I bought the car it already had a 305 tpi swapped in, it was from an automatic transmission car, found that out when i went to get my back up lights working and there was no wiring for it going to the tranny. so ive been trying to get some semblance of continuity going with my wiring. Car used to be my daily driver for many years but now that im a little older and it no longer is Im takin the time to get everything in order.

 

Yea at this point ill probably go that route of having it setup like the 91 would have been then, seems easier maybe at this point then trying to frankenstien everything together.

 

I think the 91s work by grounding the fan relay through the switch and ac pressure switch on the hard line.



Since youd be wiring it separately, just add a manual switch as another manual ground..complete control!

 

Since it has probably been butchered by a previous owner, my suggestion would be to do what I did on my '83 which originally had no electric fan. I got a fan from a '84 H.O. model, and a wiring kit from Painless Wiring which included a thermostatic switch (I selected 195° On/ 185° Off), relay, and 30 amp circuit breaker. It really was easy to wire up, and even switches the fan on when the A/C is switched on...

 

Do you remember how much the kit cost?

 

theres one on Amazon for like $30


if you plan to add other stuff, nows the tiem to put in a relay box

 

was it this one? https://www.painlessperformance.com/wc/30102

 

That's it...