I have a manual fan switch installed already and it works perfectly. I am also adding a manual antenna switch. I got a led lighted switch for the antenna and it works exactly as it should (including the light). I can't say the same for the fan switch. the light won't come on but the fan still operates normally with the switch. what am i missing?

 

Hello,
First, how many fans do you have? My 87 has a front fan and a rear(Main) cooling fan.
I used a relay to turn on the current to the front fan whenever the ignition is on. I would use a relay so as to not over-load and burn up an ignition circuit. If you are not sure how to wire a relay, there is an easy way. Buy a relay kit for switching on/off added lights, like on a four-wheel drive. The lead that the schematic(included) says should go to your manual switch for lighting, is what you hook to a lead that is 'hot' with the ignition in the 'on' position(usually easliy found in the fuse box).This will not burn up any ignition circuits from switching on/off heavy amperage loads.
The Main fan should be turned on/off by coolant temp.. I would look for a kit that works with your computer and factory wiring (for your make and model, etc.). If you can't find this, look for a temp. switch designed for aftermarket cooling fans. If this sensor does not come with a relay you need to add one. If you can copy the wiring schematic from the first fan, great all you need is another relay. If you are not certain buy another relay kit and hook the 'switch' wire to the sensor. This will keep you from shorting-out the sensor. I would install this sensor in the cylinder-head and not in the radiator. I would install a 160 degree thermostat or a baffle(never run the engine without anything where the thermostat goes, water will flow so fast that it does not have time to absorb the heat out of the engine and it will run hotter than with the baffle or thermostat.). If you can't easily find a baffle for your engine, take a factory replacement thermostat and modify it. Just take a set of side-cutters and remove the parts that open and close, this will leave you about a 3/4" restriction that will work GOOD. Don't leave any 'loose' pieces on the baffle, it can come loose and get into your water-pump etc..
Add a couple of bottles of 'Water-Wetter' and run about 30-35 % anti-freeze to the rest water. Install a new 15-17# radiator cap and you are all set.
If the car wants to run hot with this setup, you have probably got more problems. Either the radiator is stopped-up(ever put any stop-leak in there(?) That'll stop one up!) or your water-pump isn't circulating water very well, etc..
I hope this info is helpful, Take Care, -John

 

You don't need a relay to turn on either cooling fan motor. The manual switch should be connected from the fan motor relay green/white wire to ground. The fan relay coil is connected to 12v and your manual switch grounds the other relay coil wire to turn on the fan relay and the fan motor. The light in your switch requires 12v all the time and turns on when the switch grounds the external circuit. In the fan relay circuit, you only have 12 v through the fan relay coil which goes to zero volts when your switch grounds the relay coil. Forget the light on the switch and pay attention to the switch handle position that makes the fan turn on.

 

JFB ,
What I was trying to explain was how to have the fans work automatically, so they didn't have to worry about turning switches on and off. I also did not know where the wiring harness had been hacked into(at a factory relay OR at the leads to the fan itself????).
I just feel like it is better to be safe than sorry, If we're not sure where they cut into the wiring harness(s).
You are right. To be real detailed on what to do, We need more info on where the wiring was cut into and for certain what the owner wants.
In My experience, I have found that most times someone wires in manual switches, is because they are not real certain how to wire it up to function automatically. I have also seen several 'projects' like this where the fan wires were cut at the fan(s) themselves and wired-on from there.
I just didn't want this person to start burning-up and shorting-out stuff because I took for granted where they cut into their harness.
You All Take Care and Good Luck, -John

 

I see...so what you are saying is that the light will never work. I know the position for on and off, no problem...The lighted switch was more for a "coolness" factor. Any other way to make it work?

And I don't have any cooling issues whatsoever. The fan was installed for parades and sitting in Florida traffic. I don't like letting it run up all the way to 230* before that secondary fan comes on...it just doesn't leave you enough time to find a place to pull over and turn it off before serious overheating occurs.

 

There is no easy way to have the light on your switch work unless you want to add a relay or a logic circuit. You shouldn't have any serious cooling issues, GM says to shut the engine off at 260 F and let it cool down. Your engine won't get to 260 F when the fan/fans are on and the auxilliary fan comes on at 238 F, even 238 F is not harmful to your engine!

 

dave:
THANKS...this weekend i will take a look at the wires, etc and see what i can do....

 

260?

 

don't know if they addressed this in previous statements- make sure you just dont cut power and go straight to 12v because I tried that and luckly a friend of mine told me that the computer has resistors that change the returning current to 5v so if you bypass the resistor then you will eventually fry your comp. I just played it safe and went back to stock. I know, I know, I love switches too.

 

Well, I hooked it up as described, and the fan still operates, but the LED on the switch doesn't light. hmmmmmmm......