So I picked up a 1991 Z28 and the guy that sold it to me had a wire from the cooling fans connected to the battery. I have to open the hood and disconnect it every time after driving and connect it before driving. How Can I fix this? Is there a way I can wire it so it only turns on when I turn the car on and turns off when I turn the car off?

 

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Or wire it like this image at the bottom right and install the temp sensor between cylinder 6&8 in the cylinder head.


Or just in stall a fan controller !
There are adjustable ones , temp switch controlled or like this one that you would push a probe in the radiator fins.


http://www.summitracing.com/parts/pro-69599

 

I wired my fans through a relay and ran the 12v sourse to a wire that comes from the alternator...
So every time i start the car the fans turn on and i turn it off they turn off

 

Welcome to TGO!!

Wire them up factory like they're supposed to be. The diagram Tuned Performance posted is correct.

 

My 91 Z28's fan (1 of them anyway) was wired hot to the battery when I bought mine too. All it needed was to be wired back to stock configuration and a new fan relay installed.

Somebody just threw a band-aid on it to get it down the road instead of diagnosing it and repairing it properly. I think the relay was under $15.00

 

I'm not opposed to doing an aftermarket relay system for your fans if you wanted to upgrade your cooling system or were having major electrical problems but the fan relay system is stupid simple to figure out.

 

is the coolant fan come on at atart up or does the relay activate the fan at a certain temp

 

I use two switches. The first switch turns the fans on at 195 degrees at half power. At 212 degrees, the second switch activates and the fans increase to 95% power. If I turn on the AC, it's wires so the fans come on at 100%. The switches are the stock style in-block switch. They're fixed and non-adjustable. If you want adjustable, you can specify that when you talk to him or you can buy an aftermarket setup from a company like Painless or Deraile.

 

Along with the other options .......
This is what I have been running.
A very basic adjustable temp. controlled fan switch. One wire in and one wire out is all it takes to wire it in. $ 20.00 and you might need some extra wire. Don't let the price worry you. It a very simple controller, that's it.


http://www.autozone.com/autozone/parts/_/N-9pd8y?itemIdentifier=267187_69565_0_


Part # 733653


This is for a single fan that is or was controlled by the switch in the head.
After the install you can just drive your car and when it hits that temp the fan will kick on all by itself.


The fan will run until it drops to 10* below your setting. Then back on at the setting and so on. The "thermostat" and the fan will be keeping the car in that temperature range. Or that's the plan


As far as running the wire to the fuse box you mount the relay on the driver’s side in the corner by the booster. Drill a small hole in the fire wall and run that wire to the fuse box. There are slots in the back that are hot only when the key is in the “ON” position. You slide the wire in to the slot using a spade connecter.
Install the proper thermostat.
The main purpose of using the fuse box is to make it an independent circuit having nothing to do with any of the stock wiring.


Side note = Do not use the instructions that come with the controller. Very Bad.
[URL=https://imageshack.com/i/eyhC4LF7j][/URL]

 

The circuit I just posted will add wire and the probe with wire and will require it all to be wrapped in wire loom and routed nicely so it does look decent.


If you don't want that in your bay then going back to the stock wiring is my suggestion using a switch in the head that comes on at a decent temp.


By the way the prob goes into the radiator fins. There is no reason to put it in the hose as suggested.

 

OK,
Last thing =


The Compressor Works Controller I listed will also work by simply putting it on the wire your using to start the fan on the battery.


Just put it on the end of the wire run a second wire from the other side and install a inline fuse adapter then that same wire to the battery junction block on the bay wall next to the battery using the proper size O ring connecter.


Install the probe in the fins and adjust the "on" temperature and you done.


Here's a photo of the block. Unhook both sides of the battery before touching it. It is very hot at all times.

 

Good job with the diagrams Ron, really good job. This might help him more than mine if any of his circuit is still good.