Temp Switch On?

PaulProe

PaulProe

TREASURER & Web Administrator, Member # 019
GCC Member
Location
Manchester
First Name
Paul
Last Name
Proefrock
Can anyone tell me the preferred operation of an electric fan switch - at what point should the fan come on?

Some threads on the internet say it shouldn't run until temp exceeds normal operating temp. Other threads say it needs to be pro-active and come on before overheating occurs.

Kind of like the weather, don't like what you hear - switch to another channel.

Any suggestions. My car doesn't overheat but I noticed the fan is coming on as soon as the motor starts up and I know that isn't right

??
Paul

ps: posted this here since there isn't a tech area for radiators or cooling :confused:
 
PaulProe said:
Can anyone tell me the preferred operation of an electric fan switch - at what point should the fan come on???
Paul
Click to expand...

Paul:

I can't answer your question, but in addition to the auto-fan switch, I have a manual override switch on the dash. Any time I'm running in traffic or think the temperatures are going to climb, I just flip the switch and the fans come on. This keeps the engine from going above normal operating temps. Just my $.02.

Steve
PS: I spoke to Dean. Thanks again
 
My thermostat is a 185, so the fan switch I bought (that screws in to the intake) comes on at 195F and stays on until 185 or below. A lot of people do put a manual override in just in case the temp switch fails. Mine hasn't, but the fan relay itself has. You don't want it to come on at start because you want the engine to heat up, which in the coming months, won't be a problem.
 
Mine is kind of like Steves. It comes one around 195, but I can dial it in. I also have a manual override switch too.
 
Since I've become intimate with my cooling system lately.....185 deg F T-stat

Fan comes on at 95 Deg C (203 deg F)....shuts off at 90 Deg C (194 deg F).

Like others, I have a manual override switch on the dash.
 
This is a topic that I have been involved with for some time due to our rebuilt tugs and the overheating issues that we have seen in MIA.
Lets go back to the old engine driven fans.. thay are on all the time. They will not change the way, or temperture, that an engine warms up. That is controled by the thermostat. At the time the thermostat opens, the radiator comes into play and the amount of coolant flow through the radiator and the air across the fins.
Our original setup in MIA tugs was, 195 thermostat, (9 gals per minute max flow) and a Fan on temp switch that came on at 195 as well. The fan would run unitill the engine cooled to 184*.. This never happened at normal operation. The "Fix" that MIA requested was wire the fan to come on when the engine sees oil pressure and chnge to an industrial 195 "High flow" thermostat. This allows the max coolant flow through the radiator but still giving it time to disapate heat. Overheats are gone but the fan was not the cure. The way my car is set up.... 195 thermo, fan on at 200* (let the thermo always reach it's full open operation) (also my car is EFI--higher temp) off at 190*, with a manual override.
Also make sure the shroud you use makes the best use of the entire radiator.

Just my .02... but it works for me.
 
I've never understood the manual override switch, because if anything is going bad, it would be the fan relay, which the override switch would be wired through. The only thing you would be bypassing would be the temp switch.

EDIT: Good point Skip, and how mine is pretty much setup, minus the override switch
 
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Tim,

Granted relays go bad, but a good quality relay is pretty dependable.. make sure the relay is rated for the fan, as these fans can pull 25 amps.. if the relay isn't rated for that... you will burn it up.

Skip
 
My notes

All the input I am getting says the "fan on" should be around 5-10 degrees above the thermostat temp. You don't want the fan on when it isn't necessary but you want it to come on early enough to avoid any higher temps.

I also installed a manual override and can activate the fan from the dash.

Paul
 
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