Electric fan thermostat control.

AnthonyG

AnthonyG

Well-known member
Hey guys, got an electric fan cooling the engine. It's got the typical electro / thermo switch ( assuming bimetallic strip attached to an adjustable control ) which attaches to the radiator and senses the heat and kicks on and of based on that. I don't run a hood as my avatar shows and the described setup will either not kick the fan on at the warmer weather setting as it's unprotected from to the cold air influencing it or by the time I get it to kick on by adjusting the setting to have it kick on at a cooler temp on the radiator it won't kick off.

Does anyone know of a thermostat for an electric fan which installs internal to the cooling system to control the fan? This would read a real temp which would more accurately sense the temp and control the fan.
Thx
 
There are numerous adjustable switches with probes that screw into either the bottom radiator tank or into a threaded hole in the manifold, head. There are also pre-set thermo switches. Jegs, Summit, etc are full of them. I think the key here is to predetermine the threaded bung size and make sure you can adapt it to your system. Also determine the operating range that fits your expectaions. I've read many that suggest the bottom tank of the radiator or in the lower hose as the best place for the probe.
 
I had one of them adjustable ones and it never worked either the fan would not come on or it would be on all the time,i put a manual switch and use it when I need to...
 
vintage air has the control that you need.I have one on my 40 with air and it works beautifully.
 
Used to put the probe in the radiator hose and clamp it down. Also used a ferrel fitting that fit the drain in the bottom and and held the probe.
 
I don't want to be intimidated by watching a temp gauge all the time, let the fan switch do it's thing. I use an ugly davies Craig one that looks like a fridge thermostat with the probe in the top hose. Ugly as hell but adjustable and super reliable on two of our cars for the last 15 yrs.
 
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Google:- Davies, Craig. This company have an extensive range of elect fans, water pumps and controllers. Large web site with heaps of information. Regards, Kevin.
 
A major key to proper operation of the control is the temp differential between cut on and cut off. Most of the controls don't have give that in the specs. I bought a non-adjustable thermo switch that said it cut on at 195 and off at 185. I thought that was just right for my 180 degree thermostat. When I installed it I found it came on at 206 and cut off at 177 by my laser thermometer and temp gauge. I thought it was bad, so I returned it and asked for a new one. It did the exact same thing. I was looking for a more accurate switch on-line and found the mfgr. of the switch and their description gave a tolerance of 13 degrees. The Jegs website neglected to say that. I am still using the switch because it does turn on before the engine gets too hot and most times my thermostat will allow it to cool to cut off temps.
 
Your problem is not uncommon with electric fans. Many don't have a way to adjust the differential range between on and off. If it is your primary fan, it should run when the engine is running. If used as a booster, install a bypass switch so you can override the control as needed. Electric fans usually draw lots of current, sometimes more than 30 amps at six volts, so the charging system must be in top shape.
 
supereal said:
. If it is your primary fan, it should run when the engine is running. If used as a booster, install a bypass switch so you can override the control as needed.
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This switch is on my '40 with a 5.0 engine. It does control the primary fan. When at speed, the temp is always around 180 degrees and see no reason for the fan to run. I have a bypass switch on the control so I can run then fan with the automatic control or lock it on or off. I'm mainly concerned about not catching the temp creeping up if I'm distracted. I also have a smaller fan on the AC condenser that will operate with the compressor clutch, or manual on or off.

I'm interested in your reasoning for running the fan whenever the engine is on?
 
I'd also like to know why it's gotta run all the time?
If the engine ain't hot, what's the benefit of having the fan running? The benefit of a leccy fan as far as I'm concerned is that it don't run if it ain't needed.
Martin.
 
I think what I would like to see available is a switch that would allow the fan to have a variable speed, depending on the temp. It doesn't have to run all the time at lower temperature, but It would be nice if as the temp gets into a particular zone, it would start to run and increase as the temperature rises. I have looked, but I have not found anything that would do that. It doesn't look like a complicated idea as it is only controlling the voltage of the fan motor, which is DC. Anyone know of this?
In regard to the temperature sensor/on-off switch, I got mine from Classic Instruments. They are available in different temperatures and screw into the head in front of the water outlet. It is a pipe thread and works fine, just not a variable speed control.
 

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Chris Nelson said:
I think what I would like to see available is a switch that would allow the fan to have a variable speed, depending on the temp. It doesn't have to run all the time at lower temperature, but It would be nice if as the temp gets into a particular zone, it would start to run and increase as the temperature rises. I have looked, but I have not found anything that would do that. It doesn't look like a complicated idea as it is only controlling the voltage of the fan motor, which is DC. Anyone know of this?..............
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There are electronic fan controllers from Derale, Dakota Digital and Flex-a-lite (probably more) that vary the fan speed along with adjustable on/off settings. The Spal controller I am using isn't available anymore but has worked well for the last 6 years. Some, like the Spal, can use an existing electric temp gauge sender for the input. :)
 
Post #15 is the way I'll go. Will order tomorrow. Thx 1Oldtimer, with the added endorsement of you having used it successfully on several cars it's a "slam dunk"
 
AnthonyG said:
Post #15 is the way I'll go. Will order tomorrow. Thx 1Oldtimer, with the added endorsement of you having used it successfully on several cars it's a "slam dunk"
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I don't see the temp differential in the web site. If you call to order, it would be interesting to know. Also, What is the tolerance for the advertised temps?
 
HI, Take a look on line for rainbow products Fans & controls. There two speed fans & two speed controls are the best you can get.
 
Hypertech has several different ones, from fixed to adjustable, that use NPT threads...run about 35-40 as I recall through Summit, Jegs, etc.

Now, might mention it's best to let the fan switch control a relay...let the relay carry the load, to turn the fan on.
 
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