Electric fan on a thermostat or manual switch

[maczter]

Which do you use...thermostat switch in the bottom of the radiator or on a manual switch on the dash? Why? I am leaning toward a manual switch just one less thing to malfunction. Opinions please?

[Desertrunner]

Don't even consider manual switch, if you don't see it in time its all over you will cook you engine. You can have both which is some time handy in traffic.
Tony

[2FAST4U]

Use a thermostat switch mounted in the intake manifold to measure engine water temp, not radiator temp. If the thermostat ever sticks closed, you won't know your engine is overheating. You can wire a light to activate when the switch activates the fan. I did this on my Gt40 and worked great.

[Jeff Kleiner]

I do all of mine with a thermo switch along with a manual override in parallel. I also use an indicator light to show when the relay is energized by either control.

Jeff

[wallace18]

I do all of mine with a thermo switch along with a manual override in parallel. I also use an indicator light to show when the relay is energized by either control.

Jeff

I did it in parallel also with my A/C. The fan can come on with anyone one of the 3.

[sheephearder]

Use a thermostat switch mounted in the intake manifold to measure engine water temp, not radiator temp. If the thermostat ever sticks closed, you won't know your engine is overheating. You can wire a light to activate when the switch activates the fan. I did this on my Gt40 and worked great.

IMHO this is the best way!

[skullandbones]

Hi Maczter,

How's that 33 build going! I love that car. Had a steel 34 sedan. It is the real hot rod look.

Regarding the cooling fan wiring, you really should do the thermostat thing. I have dual fans from Summit and dual relay circuits so there is a sort of fail safe with those units. I am a little parinod about this part so I have a computer temp gauge (signals PCM) original, a temp gauge sensor, and the fan relay sensor. I did not take a chance on any calibration variance from sensor to sensor. So far it's working as designed. I live in AZ so it is a real test of cooling capacity. Don't want to fry your expensive hot rod engine.

Another factor is where the relays are in relation to the fans and battery. I did my battery install in the trunk but if I had it to do over again, I would put the battery in front and shorten the battery runs to the relays and the hot wire run to the fans. I don't know if you have that option. However, my wiring sizes are large enough and runs are as short as I could make them with the setup. You might want to carry an extra relay in your trunk just to save some downtime. Like I said, this is one of my more personal concerns. Good luck, WEK.