electric fan sensor

[kully 560]

this is the temperature sensor I use  ebay # is 232282757516 ,180 degree 1/8" npt threads.  the 34mm radiator hose adaptor I used is ebay # 110957401514, 1/8" npt threads  .   I installed it right next to the thermostat housing in the upper radiator hose and the sensor screws into the adaptor with Teflon tape. the sensor is used to break the ground wire on a 4 pin 30 amp relay that I pickup local at the auto parts store. the relay has 4 pins and they all use the same common terminals numbers no matter what brand .now for wiring the #30 is for a 30 amp positive wire from the battery fused , # 87 terminal goes to the fan motor,#86 terminal goes to a 12v switch positive wire, and # 85 is the ground wire that goes to the center pin on the temperature sensor, and the 34mm radiator hose adaptor has a ground screw next to the sensor that you would connect a wire to that screw and then connect it to the chassis on the car as to make the ground connection for the relay to be activated when the sensor calls for cooling on-off cycle. make certain that the center pin on the temperature sensor gets the wire from terminal # 85 on the relay because when you install the 34mm hose adaptor it touches the thermostat housing and that makes a ground connection and if you switch the thermostat sensor wires backwards the fan comes on all the time . there is not a lot of room for the hose adaptor it has to get installed right up against the thermostat housing and the upper hose bends right after it. I chose this  hose adaptor because some reviews said the cheaper ones on ebay that the 1/8" npt threads were not threaded that well . this adaptor has perfect threads and the sensor screws right in . if you decide to install a manual override switch you simply connect one side of the switch to terminal # 85 on the relay and the other side of the switch will connect to ground or chassis on the car.

Edited October 16, 2017 by kully 560

[sweatybetty]

On 10/16/2017 at 7:15 AM, Captain Obvious said:

I would assume that all depends on where you set the temperature.

I'm thinking I would want the temperature of the fan switch some token amount higher than the thermostat temp. If the system can operate in equilibrium without the fan running, then you are getting enough heat rejection from just natural airflow through the radiator. But if the temperature of the engine starts to creep above the thermostat temp, then it means the system has gone out of control and you have exceeded the heat dissipating capacity of the radiator (under the current conditions).

And at that point, you need more flow. Either more water, or more air. If you are already maxed out on water flow (thermostat is all the way open), then you need more air.

Turn the fan on.

thats why i put the sensor in the lower hose. if the water going in to the engine is too hot, for whatever reason, i want the fans on. 

[w3wilkes]

The instructions for the dual 12" electric fan setup sold by MSA has the sensor installed in the lower hose. Has been working fine on my Z car.

[kully 560]

the sensor I bought is a 180 degree sensor but when I check its operation it closes at 192 degree which then turns  on the fan that is why I installed it on the upper radiator hose . I do not know what msa sensor works at but all the internet reading I have read most use the upper radiator hose so the water coming out is not to hot . when I installed the  radiator sensor prob that thermos cool gives the instructions said to install it in the upper portion of the radiator I believe center location which would be about the same as the upper radiator hose temp give or take a few degrees. so now after installing the sensor my temperature gauge now stays on the m symbol which is perfect.