Can I use coolant switch on a "new" circuit?

[harpon]

Just wired up a direct rocker switch to my radiator fan by tapping in to the circuit fuse for the fan otherwise. I had installed the new fan a few months back- and NEVER COULD find any stupid plug to plug the connector back into- I looked everywhere for it - very frustrating

So anyway I put the rocker switch setup yesterday and it works OK- I can turn the fan off and on manually, and it has an inline fuse (A "tap" double fuse I got from china on ebay wouldn't go into the fuse box, although a fuse goes in no problem- cut the blades down and still no go- another frustration

Then later I got thinking- I wonder if I could just establish a new circuit and just run it through the coolant sending switch that comes out of the thermostat housing and just let turn the fan on and off like it's supposed to?

I think it works in reverse- and like the kill switch on my motorbike, grounds out the circuit that otherwise has power? I'm not that hip to the electrical thing- but it only has ONE terminal, so I assume that that is HOT. How does that work, and what would I need? I still have another inline fuse holder and the other one I'm using off the fusebox already.

Does it have to have some relay? If you know how to do this can you give me some advice or even a diagram sketch?

the direct wire up and switch works pretty well otherwise. I/ m out there in HOT Florida heat and the motor has to run about five minutes before it even starts to register on the gauge. The ancient 91 A/C is even working but rickety......

[ryanprins13]

Can I use coolant switch on a "new" circuit?

The sensor is ground. Not sure if it breaks ground to turn fans on or connects ground as mine doesnt work. Test it. With a cold engine does the sensor tab have ground? If not then ground is fans on and you can hook it up to your fan ground wire and run the hot wire to the fan direct from the battery or fuse box. If the fan runs slow then there is probably not enough current getting through the sensor to run the fan and you should find another solution


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[Eaglefreek]

Yes you can use the factory fan switch(sensor) in your "new" circuit. I would suggest using the switch to activate a relay instead of running full load through the fan switch or rocker switch.

[Damkid]

Yes you can use the factory fan switch(sensor) in your "new" circuit. I would suggest using the switch to activate a relay instead of running full load through the fan switch or rocker switch.

Agreed

[Movin]

Any bosch type relay rated for 30 or 40 amps should run your circuit.
Pin 30 should be ground and should use 14 gauge or better as it will ground the fan.
Pin 87a should also be heavier wire and will go to the fan, ground side. Pin 87 is not used.
Pin 86 can be smaller wire like 16 or even 18. It will be hooked to switched power.
Pin 85 can also be smaller wire and will go to the coolant switch in the block.

The relay turns on to shut the fan off. If you unhook the wire to the sensor while the key is on the
cooling fan will turn on. If you have heat problems and a good battery you can substitute battery power for switched power. This will keep the fan circuit able to turn on should the coolant go above switch temperature even after you turn the car off. This can help some carbie cars from boiling carbs dry with todays super lousy fuel.

If you have AC the yellow wire with red stripe from the AC relay should be connected to pin 87a as well.
The yellow wire at the AC relay should still be hot if your AC works with stock wiring ( you have not done something to make a dead AC system work).