I want to put my electric fan on a switch that I can turn on manually. Right now it turns on when the temp reads 220 (too late already boiling into overflow) or with the AC condensor. I want it still to be able to turn on with the temp and the sensor, but I want to be able to manually switch it on when I see the temp gauge creeping up.

Can I just run a 12V from the fuse box (something on the ignition circuit) to the switch and then to the fan relay plug that gets juice from the AC condensor and/or the temp sensor? This way it (the relay) can get 12V from the standard or from my switch. If I run this, what happens when the AC sends 12, does that go to my in-cab switch or will it just go to ground?

I am a wiring idiot, all black magic to me.

I have a 97 XJ with 4.0. I am sure someone with TJ's have done this same thing.

THanks for your help. (Maybe not college level, but I did build my own steering, suspension and bumpers if that helps :flipoff2: )

SeanP

you need 3 diodes.

a diode is a one way valve for electricity.

put one on each power line feeding to the relay

(one for your manual switch, one for the AC on feed and one for the temp feed).

Radio shack might carry them. They don't need to handle much current. most relays only need a few hundred milli amps.

You can also do this with relays, but IMO its easier with diodes.

- Dan

after reading your question again, why not just get a lower temp sensor to turn the fan on? then it stays automated

Originally posted by SeanP
I want to put my electric fan on a switch that I can turn on manually. Right now it turns on when the temp reads 220 (too late already boiling into overflow) or with the AC condensor. I want it still to be able to turn on with the temp and the sensor, but I want to be able to manually switch it on when I see the temp gauge creeping up.

Can I just run a 12V from the fuse box (something on the ignition circuit) to the switch and then to the fan relay plug that gets juice from the AC condensor and/or the temp sensor? This way it (the relay) can get 12V from the standard or from my switch. If I run this, what happens when the AC sends 12, does that go to my in-cab switch or will it just go to ground?

I am a wiring idiot, all black magic to me.

I have a 97 XJ with 4.0. I am sure someone with TJ's have done this same thing.

THanks for your help. (Maybe not college level, but I did build my own steering, suspension and bumpers if that helps :flipoff2: )

SeanP

Hey Sean,

If you already have a relay for the fan, you can leave the power on it and make a bypass by supplying power from bat + and then through a switch and then to the relay. It will work fine.

Edit..I rethunk myself..and rewrote the above.

Thanks guys. I just got my diodes from Radio Shack. I should have this together tonight. Then, I just hope Dutchman gets my axles to me and Driveline service gets done lengthening my driveline. Oh yeah, and the blender mod mentioned on TOTW so we can have margs and mudslides this weekend.

SeanP

Why even fool with the power side? Just hook a wire up to the ground side of the relay in series with a ground.

The pcm controlls the ground side of the relay. Running another switched ground to the relay won't hurt the pcm. 1 wire, not 3 diodes. The advantage to this, is simplicity in wiring, and protection. If your wires shorts to ground, all it will do is turn on the fan.

Originally posted by SeanP
Oh yeah, and the blender mod mentioned on TOTW so we can have margs and mudslides this weekend.

SeanP
Already got that covered. :smokin:
Looks like I'll be up there Thursday night.


Jes

Jes, you coming to Sacto thursday PM? Ya got an open bed here. I have to work for a few hours on Friday (end of the quarter stuff) but I should be ready to go. My dutchman shafts are to be here Thursday.

SeanP

Actually I'll probably head up there Thursday afternoon and get my C02 filled at Salon Fire Control, then head up the hill and meet Andy in the evening. I don't know what the plan is, if were gonna night wheel in or what. Andy has to be back by Saturday night, and I want to be back by Sunday morningish to beat the horrific traffic I must traverse to get home to the :rainbow: city in which I live.

Jes

Plan is to meet at wentworth trailhead at 4:30 PM on Friday. We'll be on Ch 22. Maybe camp a little past ellis creek on Friday night. Page Far-n-gone Hippy Tom on the CB if we don't hook up at trailhead.

SeanP

Originally posted by Jes
Actually I'll probably head up there Thursday afternoon and get my C02 filled at Salon Fire Control,

I hope you know they moved last summer and are not in folsom any more and are somewhere in Rancho.

Originally posted by Dan-H


I hope you know they moved last summer and are not in folsom any more and are somewhere in Rancho.

Ya, they're on Luyung off of Sunrise kinda near RE I believe.

Jes

Jes, take sunrise south to whiterock (this is before the turnoff for RE). Turn left on white rock, then take the first street on the right (past Costco). They are about 1/4 mile down on the right. They like wheelers there and should be able to fill your tank while you wait.