Max

I like to let my coolant fan run after I shut down the car. I know that the effect is limited because the water pump isn't running but when I get home I always like to raise the hood and let the fan run to help ventilate fumes and cool every thing down.

I would like to have the fan run off of the battery instead of the ignition so that it will keep running without the key in the ignition until it cools down enough to where the coolant temp switch shuts it off.

It might also be nice to have a toggle switch in the cabin so I could shut it off manually if I wanted to for whatever reason.

How can I keep normal function of the temp switch add a manual overide and have the ability to run it with the ignition turned on?

deadbird

This should help..

https://www.thirdgen.org/techbb2/sho...hreadid=119068

Max

Thanks. I read that thread but I dont really get it.

how do I wire in the toggle switch and how is it that it will keep the operation on the temp switch.

My understanding of electronics is fairly limited.

Thanks for the help.

deadbird

The tan/white wire (this is assuming factory relay/wiring) that is tied into the heavy gauge orange wire you see going to the battery is normally on a ignition switch source from the fuse panel. When the key is off normally, there is no +12v on the tan white wire to power the relay. In the diagram (attached so you don't have to flip between post to look), the tan wire is now power constantly keeping +12v on the relay all the time. Now, when the relay is grounded (by the green or green/white stripe wire), it will be powered & the relay will switch the fan on, ignition on or not. If you use a lower fan temp switch and the fan is running while you park the car, the fan will stay running untill the switch reached the predetermined temp to unground making the relay kick off. If you tie a toggle switch inline with the fan switch (or just use the toggle inplace of the switch), you will be able to turn the fan on as you please or let the fan switch do its job. I hope that was sort of clear.. I didn't quite get all my 'beauty sleep' in last night :sillylol: (altho even 8hrs sleep wouldn't make me look any better )

Danno

I know a lot of the smaller 4cyl cars have setups where the fan will continue to runafter the car is off but these are generally ECM controlled and use the coolant temp sensor which is generally located closer to the radiator. On a TG your fan switch is all the way back at cyls 6-8. You may be surprised how long the fan will have to run to bring the temp down low enough to turn it off especially with no water flow from the pump. Just a thought, but I would be concerned about battery drain.

Max

That's all very helpful.

If I understand correctly I should run a wire from a battery slot in the fuse box to the relay where I cut the tan wire and splice the relay end of the tan wire to the new power source. Then to ad the toggle switch, I attach a wire from a ground to a togle switch then from the toggle switch to the relay where I cut the green wire and splice the new ground to the relay end of the green wire.

I have an optima battery which I have been very impressed with. I don't expect battery drain to be a problem. However I want to ad the cut off switch so that if for example the car is parked in the hot sun and I expect it will take an extra long time to cool off I can overide the circuit. Also, if experience any low voltage emergency situations I also have that option.

Then do the long pieces of the tan and green wires become unecessary? I would probably cut them out If I can.

I just removed all of the wiring from my old TBI system and I'm cleaning up the engine bay as best I can.

Please let me know if there is any thing I have misunderstood of missed and thanks again.

Danno

You do NOT want to cut the green wire. If you do that you will lose automatic control of the fan by the fan switch in the engine. You want to tap into the green wire. 3M makes connectors that can tap into a wire to add a wire. There is a major flaw in the diagram to do this and I will tell you what it is. It shows moving the tan/wht wire over to the org battery feed. The org wire is fed by a fuse link with higher current rating than the current feed from the fuse panel. If a short occured there would be danger of melting the wire and possibly worse. If you jump to the org wire use an inline fuse holder with a 5 or 10 amp fuse. That's more than enough to run the fan relay. If you come out of the fuse panel from a hot batt line do the same thing. After the fuse then go to a toggle switch, then to the tan/wht. Here is a problem to consider, if you cut the tan/wht wire then you will have to make sure it is always on when running the car because the relay now gets it's operating voltage from the switch and not the key. Tapping into it eliminates that potential problem, however the tan/wht wire has a junction that also feeds the alternator sense wire. It goes into the voltage regulator in the alt and I am not sure if having voltage there poses a problem if the car is off. It shouldn't but the info on the regulator IC I have is limited. Since the factory controls it with the key I suspect there is a reason. To run the fan manually you can use a second switch and simply ground one side and then tap into the dk/grn wire anywhere it is convienient. You can also if you want purchase a double pole double throw single switch which essentially has two seperate halves. One side can do the voltage, the other side the on-off manual control.

John Millican

iTrader: (1)

I do not recomment letting the fan run till the temp switch shuts it off after the engine is off. It can continue to run for an hour or more and KILL the battery.
I speak from experiance.

deadbird

Danno.. I'm afraid the current to the fuse panel is exactly the same as to the orange wire. The only difference being, more crap sucks power off the feed at the fuse panel.

There is no difference powering the relay off the fuse panel than powering it direct from the battery (orange wire), the only suggestion I'd have (is the same as you) is fusing it.

Also, if a short happened, it wouldn't matter the source it waas connected to, the fuse would blow all the same.

I do have to agree with you and John about the battery drain situation tho (speaking as a former 2.2 dodge owner... )

SSC

Ok enough of the tech talk. If you want to keep the fan running after the engin is off "I personally wouldent" all you need to do is cut, tuck and rewire. The fan wires "at the fan's plugin" can be cut an tucked away in some plastic sleving, it's simple and all you need to do to stop a check engine light is ground the ground wire "the fan swich plugin". Now run the hot wire from the fan to the battery or 12v constant source with 12 g wire, then take the ground wire and run it to the fan swich on the head, grab a double/twoway connector "red" and cut the plastic on one side back where you can see the inner metal tube, connect it to the fan swich and your set. The fan will run have the same on off temp, will run constant and if for any reason you want to change back you only cut two wires. I did this on a guys GP a few years back and its still running fine although it can kill a battery.

Chevy83Z28

I'm a little confused on how he's wiring up his switch. The way you guys make it sound is that you're telling him to wire it in parallel with the water temp switch in the head, meaning that either the water temp switch or the manual switch will give the relay a ground to turn on the fan. But in this case, when he has the manual switch turned off, the water temp switch will still turn the fan on (and drain the battery.)

Wouldn't he have to place the manual switch in series in the wire he uses to apply 12V constant to the factory wire that only has 12V with ignition? So that with the key on the fan will always have power, assuming the water temp switch is activating it. But when the key is off, the manual switch will determine whether or not the relay still gets its 12V?

I'm a little confused on the electrical side of this but I'm hoping somebody will be able to make some sense of my mumble-jumble

Thanks guys --Rob

deadbird

I answered the question as it was titled... "I want my fan to run after I shut the car off."

There are several ways to accomplish this beyond what is above. What I suggested is the simplest solution to the question asked.

Danno

The only reason I pointed out the difference is that my drawing shows the contact side of the relay going to a fuse link directly, seemingly a different point than where the fuse panel gets fed. Also the difference in wire guage necessitates an additional fuse of some sort because that tells me that the value of the fuse link is greater that what the coil side wire can handle.