Electric fan wiring?

[price209]

Sorry if this is a dumb question, but when hooking up the relay for the electric fan, can I splice into the temp sending unit for the dash, or do I need to mount a second temp sensor? If I need a separate, i have an edelbrock performer and am wanting to know which ports should be used for the temp sending and which for the heater line? I have read that the back of the motor doesn't give the best temp reading so should I use a rear port for the heater line then. Anyone got pictures of a similar set up? 302 with explorer serp, carb, and electric fan.

 

[Broncobowsher]

Can't splice into the stock sending unit. That is just a variable resistor. And with the way the IVR works, not even a consistent reading.

My preferred method of controlling an electric cooling fan is a bit unconventional, but is now being used by some OEMs. I watch the water temp leaving the radiator. It requires a lower temp sending unit than typical. I think I last used a 160 on/140 off. It is really simple in how this works. So long as there is cool water entering the engine, it will regulate with the thermostat and stay at the proper temp. On the highway you don't need a fan with good ram air. So why run one just because you are at normal operating temperature?
When you don't have the airflow the water isn't being cooled enough in the radiator. The water leaving the radiator starts getting warm. This triggers the fan to cool off the radiator. When the water is cool enough, the fan turns off.
This of this, the fan is not cooling the engine. That is true. It is cooling the water in the radiator. And it only needs to cool when the water coming out is too warm.
Now I mention OEMs are now using this. I've seen new engines that have an added coolant temp sensor on the lower hose. Senses how warm the water is coming into the engine and if more fan is needed to cool that water.

The traditional fan switch is mounted in the intake by the thermostat. Often there are not enough ports to run it. There is a common waterneck that is tapped that can be used. It is after the thermostat. So only after the thermostat opens will the hot water reach this sensor. Now the tricky part of doing this, what sensor to use. You need to control the on and off switching points. Do you go low and have the fan run all the time there is any temp in the engine? You can get switches that come on before the thermostat opens. OK, so you step up a little bit and find a switch that turns on after the thermostat temp. What is the turn off temp? Usually a 20° swing on the thermal switches. So a 180° thermostat and a 200° on switch will probably never turn off as the switch will rarely cool below the 180° thermostat rating. So how hot are you will to let the engine get before the fan goes on? OR run a fan all the time even when it isn't needed?

 

[camp9k]

just finished hooking my new fan up...still need to clean up the wiring but super happy. After my 2nd new derale controller failed I bought a flex lite. I purchased the 3 way switch as well...This way I can have the temp sensor control it, override it or turn it off for creek crossings..I used an arb switch bracket to mount under my dash. The temp sensor in in my water neck. works great so far!

https://www.summitracing.com/parts/flx-31163

https://www.summitracing.com/parts/flx-31143

https://www.summitracing.com/parts/arb-alsb1

goodluck!
John

 

[price209]

Can't splice into the stock sending unit. That is just a variable resistor. And with the way the IVR works, not even a consistent reading.

My preferred method of controlling an electric cooling fan is a bit unconventional, but is now being used by some OEMs. I watch the water temp leaving the radiator. It requires a lower temp sending unit than typical. I think I last used a 160 on/140 off. It is really simple in how this works. So long as there is cool water entering the engine, it will regulate with the thermostat and stay at the proper temp. On the highway you don't need a fan with good ram air. So why run one just because you are at normal operating temperature?
When you don't have the airflow the water isn't being cooled enough in the radiator. The water leaving the radiator starts getting warm. This triggers the fan to cool off the radiator. When the water is cool enough, the fan turns off.
This of this, the fan is not cooling the engine. That is true. It is cooling the water in the radiator. And it only needs to cool when the water coming out is too warm.
Now I mention OEMs are now using this. I've seen new engines that have an added coolant temp sensor on the lower hose. Senses how warm the water is coming into the engine and if more fan is needed to cool that water.

The traditional fan switch is mounted in the intake by the thermostat. Often there are not enough ports to run it. There is a common waterneck that is tapped that can be used. It is after the thermostat. So only after the thermostat opens will the hot water reach this sensor. Now the tricky part of doing this, what sensor to use. You need to control the on and off switching points. Do you go low and have the fan run all the time there is any temp in the engine? You can get switches that come on before the thermostat opens. OK, so you step up a little bit and find a switch that turns on after the thermostat temp. What is the turn off temp? Usually a 20° swing on the thermal switches. So a 180° thermostat and a 200° on switch will probably never turn off as the switch will rarely cool below the 180° thermostat rating. So how hot are you will to let the engine get before the fan goes on? OR run a fan all the time even when it isn't needed?

So where do put your temp sensor? Are you using the rod style in the lower radiator line, or using a sensor mounted on the back half of the intake?

 

[price209]

So I looked at my intake tonight and I have the Edelbrock Performer 289 which doesn't have any water ports in the rear. Has anyone had luck with the probes that go into the radiator fins or the probes that go inside the hose itself?

 

[Broncobowsher]

So where do put your temp sensor? Are you using the rod style in the lower radiator line, or using a sensor mounted on the back half of the intake?

Radiator drain plug is ¼NPT or a surface temp sensor on the cold tank. Fin probes are very finicky about placment.

 

[bmc69]

I mounted the temp on/off switch (mine is 3/8" NPT thread, male) just before the thermostat. I think the one I've got is a 185/175 differential on the on/off. It controls a relay that turns the fan on and off.

I had one of the clunky FlowCooler fan control units with the fin probe, and abandoned that in favor of this much simpler/cleaner (but not adjustable) approach.

The coolant temp sender for the EFI is just behind it; you can see both sensors in this pic.

 

[Steve83]

I'm more concerned with the temp EXITING the engine - if it's too hot, the fan comes on. This & the NEXT few show several ways of wiring several kinds of fan motor:


(phone app link)

 

[price209]

If the fin mounted probes aren't good, I'm still at a loss as to where to put an in line sensor. I have found the adapters that you can put in line in your upper hose like the one in the link below, but it takes 1/8 npt sensor and all the kits come with 3/8 npt sensors. I only have 2 water ports on my intake, 1 for dash temp sensor and the other for my heater hose.

https://www.amazon.com/Dewhel-Alumi...&sr=1-2&keywords=radiator+hose+sensor+adapter

 

[bmc69]

If the fin mounted probes aren't good, I'm still at a loss as to where to put an in line sensor. I have found the adapters that you can put in line in your upper hose like the one in the link below, but it takes 1/8 npt sensor and all the kits come with 3/8 npt sensors. I only have 2 water ports on my intake, 1 for dash temp sensor and the other for my heater hose.

https://www.amazon.com/Dewhel-Alumi...&sr=1-2&keywords=radiator+hose+sensor+adapter

I found these 1/8" switches whilst searching for the one I did use..

https://www.ebay.com/itm/4-PACK-180F-RADIATOR-FAN-THERMOSTAT-SWITCH-1-8-INCH-ELECTRIC-TEMPERATURE-PROBE/232007559346?epid=2282185204&hash=item3604ba68b2:g:Xv8AAOSw7XZXgQje&vxp=mtr