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fan soft start question

truck7575

truck7575

NAXJA Forum User
Location
georgetown
I have two huge electric fans wired up, they come on as soon as I key on to start the vehicle. Does anyone know of a way to make them not come on until the engine is running or some kinda delay so that I have time to crank the engine before they come on.
 
thanks, ill check them out.. so you know if the engine is already hot if they will come on with key on or only if engine is running?
 
Depends on the controller you get. Some models have a delay built in to allow for starting. They can also be wired to continue to run after shut-down.
 
I use a Derale 16759 controller it’s cheap and does the job. The fans only run at the set temperature when the ignition is on. It’s adjustable anywhere from 150 to 240 Degrees F. It has an AC override but if you don’t have AC it can be used as a manual override.
 
Before ordering a controller check the amperage of your fans the controller I listed is only good for 30 Amps. If you go over you will need a separate controller for each fan.
 
Or even cheaper yet... Find a temperature sensor that turns on and off and the specific temperature you want then use that to control a relay or two. You could also use two temperature sensors that opperate at 2 different temperature ranges, allowing the second fan to come on only when your motor gets really hot. Then for redundancy you can wire in a manual switch(s) as well.
 
truck7575 said:
I have two huge electric fans wired up, they come on as soon as I key on to start the vehicle. Does anyone know of a way to make them not come on until the engine is running or some kinda delay so that I have time to crank the engine before they come on.
Click to expand...

Maybe I'm missing something here... How are they wired up now? Are they on relays already? Do you want them to run continuously whenever the engine is running, just not when you're starting?

If so...

I'm assuming if they don't kick on until you turn your key on that they are on some sort of relays. If that's the case, instead of using a "ST-RUN" ignition source to activate their relays, use a "RUN" ignition source. That way the fans will be shut off while starting the vehicle, but will come on as soon as the key returns to the RUN position. The HVAC system is one example of a circuit already set up like this to decrease the draw during start-up.

If not, lots of other good suggestions regarding sensors and controllers and whatnot have already been made...
 
I currently have each fan set up with its own 40 amp relay grounded in the cab with a switch for each ground wire in the cab so that I can turn them off by interrupting the ground from inside the cab. I really could care less about what temperature they come on I just dont want them on when I start the vehicle... Although I can see the benefit of only having them on when the temp is at a point that it needs it. I have manuals with all the wiring diagrams but I am really not sure which wiring is the best to tap into for a run only power source.. Currently I just have them wired to a keyed on wiring source.
 
TBI and TPI camaro's and firebirds from 87ish to 92 utilize a thermostatic fan switch. its a 1 wire switch that goes into the pass side head. it flips on (closes the circuit) at 190 and turns back of at 175 i believe
u could get more info on it at WWW.Thirdgen.org
 
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