black magic (or any electrical) fan users

[avbcon12]

i have a black magic fan on my 90 GT, the only thing i dont like is how it turns on right when the key is turned to the ON position.

example:
after ive been driving and the motor is hot, i shut the car off and wait a little bit. i go to restart my car and the fan comes on drawing a lot of amps upon startup. making the motor hard to turn over.

is there a way i can "time delay" the fan to come on?? or do something that will make the fan come on a little after the motor has started?

thanks,
adam

[PKRWUD]

The fan should not be wired into the ignition switch in the first place. It should be wired, through a relay, straight to the battery. That way, when the sensor is hot, the fan comes on and cools it, whether you are in the car or not. This helps it to cool quicker, so that it isn't needed when you restart.

Take care,
-Chris

[avbcon12]

well ive got the switched line to a switched power source under the hood so my fan will turn off when the motor isnt running. that way it wont drain the battery... maybe i shouldnt do that.

even short stops like a gas station (3 minutes) the fan will still be running while the car was off if i have it wired to a constant power supply.

but anyway, upon start-ups my car is hard to turn over due to the high amp draw when the fan is on. if there is a way to delay the fan from comming on somehow i would rather do that then have the fan run constantly...

by the way, the car is only street driven during the summer. if it were a drag car i would have the fan on all the time..

thanks,
adam

[Mustang_289]

We have a BlackMagic flex-a-lite installed on our stang. The wiring instructions tells you to hook it up to the ignition. We have the same problem when the fan is on and you crank the motor - it's obvious straining the ole amp juice.

Even if you wire it directly to the battery with a relay - you'll still have the same problem if you shutdown for a few minutes and you've got the same cranking issue.

I'm thinking about hooking up a relay with a switch on the console that will kill the fan until you're cranked up..

[avbcon12]

that is what i was thinking but i dont want to have to do that everytime i start my car, if it comes down to that i will. but i would rather get a time delay relay if one is even made. i dont even know if such a thing is out there.

how do other fans work? or do they all do the same thing??

someone help!

thanks,
adam

[PKRWUD]

Most electric fans, including virtually all factory electric fans are wired to a constant BAT+ source, rather than the ignition switch. The point is to cool it when it needs to be cooled, not just when you're in it. If when you stop and shut off the engine, the fan stays on for more than 5 minutes, either the sensor needs to be adjusted, or there is another problem in your cooling system. 90% of the time, the fan should have cooled enough to shut off before you go to restart. This means that there won't be another item competing with the starter.

If you are hell bent on powering it from the ignition, and you want the fan to pause while starting, the answer is simple. Use a relay, and have the trigger wire attached to an accessory fuse source. Accessory fuses and power sources are cut off when the ignition switch is turned to the start position, and then powered when the key is either in the run or Acc position. This is why the radio, the lights, and every other accessory shuts off when you turn the key to the start position, but comes back on when you release the key.

Take care,
-Chris

[avbcon12]

oh wow, i didnt even think of that Chris. great idea!

ill do that.
thanks,
adam

[avbcon12]

can somebody explain this to me better here?

i heard that i could use the starter relay "exciter" wire as a signal to turn on a relay to cut power to the fan... but i dont understand how i can do this or where the "exciter" wire is...

please explain, thanks.
adam

[avbcon12]

can anybody tell me what nd where the "exciter" wire is on the starter relay? and if it will work???

thanks,
adam

[PKRWUD]

It's the small wire that plugs onto the little post on the relay. The wire is usually red with a blue tracer.

Take care,
-Chris

[avbcon12]

ok thanks Chris.

do you think it will work if i "reverse" wire a relay, meaning to cut power when that "exciter" wire gets power to shut off the fan?

thanks,
adam

[PKRWUD]

I suppose, but I wouldn't. If you must wire it to the ignition, I would just what I said above; wire it into an accessory circuit.

Take care,
-Chris

[shadowblue89]

Not trying to step on someone's toe's but if you guys have a problem where it is hard to start your car because the fan is on I would look at something else. You might have a battery thats just not strong enough anymore or your starter is drawing too much amperage.

The only reason I say this is because my electronic thermostat that kicks on my fan died so I wired it up direct to the rear defroster switch(i have no defroster but had spare switch that I modified) for when the key is turned forward the fan comes on. I also live where the temperature outside is already getting around 100+ degrees and never have a single problem starting the car. My fan is from a Mark VIII and draws around 70 amps just to turn the thing on.

[Joe50]

Also there are some accessory circuits that do not have power when the ignition switch is in the start position, but are on in the run position...this is what I did with my fan. When i'm starting the car the fan has no power, when i back the key back into run the fan come right on, and the car starts with little effort...
Just a thought.

[mustangman65_79]

Originally posted by shadowblue89
Not trying to step on someone's toe's but if you guys have a problem where it is hard to start your car because the fan is on I would look at something else. You might have a battery thats just not strong enough anymore or your starter is drawing too much amperage.

The only reason I say this is because my electronic thermostat that kicks on my fan died so I wired it up direct to the rear defroster switch(i have no defroster but had spare switch that I modified) for when the key is turned forward the fan comes on. I also live where the temperature outside is already getting around 100+ degrees and never have a single problem starting the car. My fan is from a Mark VIII and draws around 70 amps just to turn the thing on.

I too have no problem starting my car when the fan is on. I have a switch that turns my fan on and off, and sometimes I leave the fan on for more then ten min, but when I got to start it, it starts up fine. U might have a weak batt, or a poor ground. Usally it's a poor ground that the problem. try a bigger ground wire and also try to find a new spot on the engine to ground it to. My friend found outhat this was his problem. He bought a new batt, but was still having slow cranks.

[avbcon12]

well, i fixed the problem. i knew it wasnt the batt. or the starter.

i put the fans signal wire into an ignition line at the key (under the dash) that only has power in the run position. so now when i go to start the car i turn the key to the run position and the fan runs (when the temp is hot enough) and then i start the car and the fan will turn off. once running the key obviously goes back to the run position turning the fan back on... it works great!

and if i want it to stay on while the car is off i just turn on the manual switch.

thanks guys for your help,
adam

[PKRWUD]

No problem! I'm glad it worked for you.

Take care,
-Chris

[Mustang_289]

avbcon12 - did you punch into the fuze panel for this connection? I did the same - but my fan stays on when I crank. Maybe I need to find another circuit to use?

[avbcon12]

no, i didnt go into the fuse box. what i did is went right to the ignition switch. there is a harness comming off of it with maybe 5-10 wires (maybe 10 or 12 guage, big). the one i used is a grey with yellow tracer. if you find that use a test light to see if it ONLY has power in the on (key) position. when you get the right one put the "switched" lead from the fan on that wire. tap into it.

that way the fan will ONLY come on when the car is running. it wont even come on when in accessory. unless you flip the manual switch for the fan. then it will come on whenever you want...

i hope this makes sense...

adam

[Mach 1]

Originally posted by PKRWUD
Most electric fans, including virtually all factory electric fans are wired to a constant BAT+ source, rather than the ignition switch. The point is to cool it when it needs to be cooled, not just when you're in it. If when you stop and shut off the engine, the fan stays on for more than 5 minutes, either the sensor needs to be adjusted, or there is another problem in your cooling system. 90% of the time, the fan should have cooled enough to shut off before you go to restart. This means that there won't be another item competing with the starter.
Take care,
-Chris

While I agree with what you are saying 100%, it doesnt seem to work this way with the black magic for the mustang. My experience with this particular fan has been the fan running on and off intermittantly for HOURS after the engine is shut off. I think it is in the poor design of the thermostat sensor, as it heat soaks off the radiator after its cool, thus turning on again, and then the fan air cools it down...turns off..heat soak..on again..

I got so tired of people telling me my fan was running(and concerned about draining the battery) that I rewired mine also.