I'm thinking about putting a power-down timer on my E-fan after the truck is turned off. I've designed a simple circuit that gives me about 30 seconds of operation before power to the relay is cut. Anyone else using a count down timer for their e-fan? Can I have your circuit for comparison? Mine is pretty simple, but with all things there could be better ways.

I don't want to rely on the temp relay to kill the power because if that fouls up and never opens I'm left with a dead battery.

Thanks.

 

Why run the fan after you shut down the engine at all? In its stock form, when the engine stops turning, so does the fan.

Just curious.

 

Maybe cause I'm falling for the current New Car e-fan hype? Most newer cars with the e-fan continue to run for a short period of time, some of them cycle, I figure there has to be a reason. Other than a small drain on the battery.

So, I guess the real question would be...Why do the newer cars/trucks do it? Any benefit? That answer would be my answer. LOL

 

Actually, it isn't really a recent development. E-Fans have been doing this since they came out. Why? I haven't a clue, and am unable to come up with a good answer. Most folks seem to think that is is to 'help cool the engine', but, that just isn't the case, as the coolant is NOT circulating. All you are doing is cooling the fluid that is currently in the radiator. You might get a bit of convection flow, if the thermostat is open, but, aside from that condition, I don't see that it accomplishes much beyond another system to fail, and run your battery dead. It would be a simple matter to just run the control circuits for the fans, (and main power) from an unswitched source, and let the fan control thermostat deal with it.

Quite honestly, I really don't see the point. The coolant isn't circulating, and the stuff in the radiator will cool fairly quickly even without forced airflow...... will running the fan speed that process? You bet. Is it necessary? I wouldn't think so. Of course, I am not an automotive engineer either..... I just fix 'em.

 

You got me thinking about that. I can't find an answer either. There is some stuff about a cool down for turbos. I know it's not "newer" cars per say, I don't know when it started, I know my 94 doesn't do it, but the 96 does. I wonder if maybe it's to cool the radiator so there is not radiant heat cooking the electronics of some of these e-fans? Or maybe electronics around the radiator? sure there's going to be radiant heat from the engine till it cools, but that would be one source instead of being sandwiched between two. And maybe I'm pulling stuff outta my ****.

And maybe I just like fiddling with simple electronic circuits...prob close to the nail on that one.

edit: In all likely hood the fan continues to run cause the engineers are letting the temp pot to control current flow rather then put the circuit on an ACC switched circuit. Less wiring, fewer relays to worry about.

 

Yeah, I can really identify with that one.

 

i had a friend put a temp prob on his e-fan. it was actually kinda cool i thought. his fan would kick off and on every 10-15 min for about a min at a time and then stop once a certain temp was hit. but this was on a 80's volvo.