Electric fan wiring HELP

[CarQz17]

FYI this is a maradyne fan kit and harness and the car is a 69 firebird with a pontiac 350 in it. Intake manifold is an edelbrock performer RPM.

I have the whole thing installed except two things. I need to find a place for the thermoswitch and hook up the ignition wire. Why does it need an ignition wire? Should I hook it up to something in the main harness or something up front in the headlight harness? I would rather not splice a wire but I will if I have to. Any ideas?

Also it says to install the thermoswitch in the intake manifold but all of the hole sizes and threads are different. They are also different in the block by the headers and in the petcock area of the radiator.

Ideas??

Thanks!

[wmhjr]

I think the first thing you should do is carefully take a look at whatever documentation you got with the fan kit. Fans generally take a 30 amp circuit, and there is a reason for that. There is also typically a relay included for the fan. Just trying to splice the fan into an existing circuit without some investigation could easily overload a circuit, causing the fuse to blow easily, killing your fan when the motor is hot as well as whatever else is on that circuit.

The reason the fan calls for wiring into the ignition circuit is because most people only have the fan active when the temp is over a certain temp AND when the ignition is turned on (either accessory and/or run). That way, after driving the car, the fan shuts off when the ignition is switched off. Otherwise, the fan will keep running until the engine cools down. Some people prefer this mode, but most do not as it's pretty hard on a battery system.

You're going to have to determine the best place for your combo to install the temp sensor. There are sensors that can be installed in the radiator, which will be a cleaner install. In any case, when you determine where you want to put it you'll then need to source appropriate fittings/adapters to mount the sensor.

[H2Ogbodies]

If the fan kit was any kind of quality, it should have a variety of bushings to adapt to various thread sizes. If you are running a factory harness, your fuse box should have an IGN terminal to use and yes, you should verify the wiring diagram for a proper use of the relay that should be included.

[CarQz17]

The harness has a relay and it has been installed in a professional manner thus far. It does not come with bushings/adapters can I source this somewhere? I would like to put it in the radiator but the sensor is bigger than the existing bung, so adapting it is not really practical. The only thing I can think of is to adapt to the sensor on the passenger side of the head or the bung next to the thermo housing. Which would be prefered? BTW It is powered through a bus bar with MAD's new system.

[MonzaRacer]

A adapter bushing for the thermo switch and install near thermostat. Second choice would be drivers side head between 1 and 3.
As for the ignition wire all your needing it for is the control side of the fan relay, if it is standard bosch style relay the numbering should be 85 and 86. Power goes in and the switch controls the relay. Now if you wire it straight to power, it will run for few minutes after you shut car off and may run after you shut off, BUT I have had several cars wired this way, simple fused wire to relay control and relay control to thermoswitch as it grounds to block.
Tie it into an existing key on run only line, not tied to ignition or alternator and use a tap joint, sut out about 1/2" of insulation, have about 3/4" to 1 " of wire stripped on feed wire,lay it next to open power line, wrap it around evenly till you get to other end, trim any excess, and solder it, then to make it cleaner you can use liquid tape or even over wrap with tape then seal with liquid tape. Normal joints like this in cars are called splices , and most electrical people will use mechanical crimpers and splice right in, stock harness also do the same , I prefer to do a tap joint over crimping as it is soldered.
Take time and your splice CAN be neat and clean. Its not hard.

[Type73LT]

I have Flexilite dual fans.

They were wired together.

I cut the wires to run them separate after the temp dial switch.

So the temp is a probe I have where the hot water comes in that goes thru the fins of the rad.

One temp switch which activates the relays.

Two relays 30 amps one for each fan.

Two fans which work independently if one has a problem.

[H2Ogbodies]

The problem with most dual fans is that they just can't cover enough surface area to remove enough heat for either one to be very good-oftentimes, they must run together for maximum air movement.

[BonzoHansen]

that may be why GM changed the wiring on 4th gens from one fan or two fans on full. They used a 3rd relay so to run both at 6v or both at 12v

[Type73LT]

I did it if one has a problem the other will be fine but yes it takes both in stop and go traffic.