Electric Fan key on ignition Source??

For a relay trigger or for a switch inside the car?

I will assume you need a source under the hood then. You can use a VPWR source to trigger a relay. For instance, you have VPWR going to your cannister purge solenoid (it's next to the bottom passenger corner of the radiator, which is often convenient).

I'm using the HVAC blower motor for the ignition source, its the one of the few circuits in the car where you can turn the key back and not have power. Meaning you can listen to the radio with the engine off and the cooling fan wont come on, if you start the car or have the key forward in the acc. position the fan is operational. It's like factory.

I did exactly what LiquidGT is describing. Tapped into the the circuit for the HVAC blower motor right behind the fuse panel.

But, as Hissin50 is getting at, this can only be used as a trigger for a relay. Mount the relay under the hood and get power directly from the battery.

Because he's not going to have any manual control over the fan, I still say it's easiest to use something like VPWR as a trigger source. It keeps all the wiring under the hood.

VPWR should not be functional with the key in the accessory position.

So the VPWR get constant power does it? I was afraid to use something under the hood because I thought the ECU would trigger whatever on and off causing the fan to operate ''erratically".

The Proform fan shoud have a seperate terminal for true manual control as well as the 12v igntion source.

The fan was my very first mod ever when I was a Mustang noob, so I left the wirng alone all these years because it ain't broke, but I wouldnt mind shortening the trigger wire to clean things up a little.

So the VPWR get constant power does it? I was afraid to use something under the hood because I thought the ECU would trigger whatever on and off causing the fan to operate ''erratically".

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VPWR is simple a 12 volt feed from the EEC relay. It powers most all your solenoids, injectors, coil and so on. It has constant cranking and ignition power.

Remember, the EEC actually uses ground paths to control most systems. This is more stable and safer for the EEC in the event of a short.

The fan was my very first mod ever when I was a Mustang noob, so I left the wirng alone all these years because it ain't broke, but I wouldnt mind shortening the trigger wire to clean things up a little.

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I'm with ya bud. I don't like to touch things that are doing fine. I'd leave it till you have reason to rewire it. I only mentioned it to the OP because it saves running a wire into the cockpit (if someone already hasn't done that).

What is "VPWR"? I will be doing a fan install soon. Just trying to gather info.

This was an early mod on my fox as well (first fox). I did spend alot of time hiding that wire. Wish I knew about the VPWR feed.

I'm about to upgrade to a DCC. Might have to use the VPWR feed.

Also, my ignition switch starting acting up last week. So when I lost the HVAC motor and turn signal function, I lost the rad fan as well.

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VPWR stands for Vehicle PoWeR. As you can see, it supplies quite a few items under the hood with power for relay coils or solenoid activation:

I used my red wire on the ignition coil as my 12v source. Im thinking its bot workibg. B/c fans arent turning on. And i got bad check when i checked volts. Fan positives are wired to the starter solenoid where my battery cable is. Thats fine right?

Hot wired the fans and they do turn on.

Ya the volts just bounce around 12-10-6 repeat on the nignition coil wires So maybe it's a bad spot.

One of the wires on the coolant overflow tank sensor is 12v key on. Thats what I used, has been working fine

Ya, i switched it up to that. Ran the fan power from the relay directly to battery also. Didnt work.

Im missing something. Lol. Smh.

If you don't have a high current alternator, you can forget about using an electric fan. The stock 65 amp alternator on 86-93 Mustangs isn't big enough to run the fan and the rest of the car. If you have a 94 or later Mustang, the stock 3g alternator should be fine if it is working correctly.

Switching a fan on and off manually is a bad idea. Too many guys have been distracted (hot girl kissing on their neck, too much to drink, dog tired and not thinking clearly) and cooked things because they forgot to flip the switch. An equal number have forgotten to turn the switch off for the same reasons and run down their battery.

The best fan controller available today is a DC Control unit. www.dccontrol.com. Cost is about $???. Be prepared to wait 4 weeks or more to receive your controller once you have sent in your payment. The controllers are custom made in small lots and lead times can stretch out.

Next best is a SPAL controller - $70-$170 See http://www.spalusa.com/store/Main.aspx?html=pwmv3. eBay will have the controllers for a bargain price: do a Google search and see what you find.

At the bottom are the Hayden or Imperial controllers available through Advance Discount Auto Parts and AutoZone. The non adjustable one is about $30 ( Hayden 226206) and the adjustable one is about $60 (Hayden 226204). I recommend you do a Google search on Hayden and the part number for more info.

Do not use a simple on/off switch without using a relay. The high current load can burn up the typical cheap automotive switch very quickly. The fan draws 30 or more amps and you need to use #10 or #8 wire on the fan power and ground wiring.

If you are good with electrical stuff (90% of the people here aren't), build your own controller. The numbers on the diagram (#86, #87, etc) refer to the numbers on the bottom of a typical automotive relay.



Note that the temp sensor in the diagram needs to match the thermostat in your engine. The preferred arrangement is to have it open about 5 degrees above the thermostat.

If you are an experienced electronics tech or electrical engineer, email me and I will send you the prototype drawings of a fan controller that is similar in function to the DC Control unit. It is a build it, troubleshoot it yourself item. I will not build or troubleshoot units, so it is not suitable for anyone who isn't really good with electronics.
See my post at http://www.stangnet.com/mustang-for...-sooo-much-amperage-help.859590/#post-8645840 to get the drawings and full details.

Alternate placement for a temp gauge sender or temp switch/temp sensor for an electric fan. Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.

Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.