Electric fan with fan switch

flex a lite 33054 controller

You may find it easier, cheaper and more reliable to just find a stock shroud and fan clutch and install them. It's a fool proof setup, especially if you are dealing with someone else's mess.

BKfox89 said:

So I got a 1989 mustang it currently has a electric fan on it but the previous owner did a not so clean job on the wiring. So i ripped it all a part and before I put it all back together I was curious if there is any way that I can maybe add in a like a cooling fan switch sensor some where on the motor that would trigger the fan to turn on like how some of the newer vehicles have. I was going to just run a switch but if I can find a way to do it this way i believe this would be cleaner and simpler.

So trying to see like if i can just get a fan switch sensor put it in one of the coolant sensor spots or something and have it wired to the fan or something. Trying to find some clarity on this if its a yes or a no and if its a yes how to do it if anyone has done it yet. Thank you in advanced.

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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-$120 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 https://www.stangnet.com/mustang-fo...-sooo-much-amperage-help.859590/#post-8645892 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.

Stupid question, sorry. Can someone post a pic of what it looks like with the diode wired up. Very confused by this part. Or do the relays include the diode these days?

Diode for the relay or diode for the fan?
The diode goes across the relay coil or fan motor (both are inductors).
Diode cathode goes to positive, anode goes to negative, i.e. reversed biased.
Same as the IAC (IAB).

The Bosch relay has an internal diode.

Blown88GT Thanks for responding and take the time to do so.

I understand the diagram and the use of a diode. What I want to know is how I should physically wire it. A diode is this little thin metal wire with something that looks like a capacitor or something in the middle. Do I literally put one end of the diode into the butt connector I'm using to connect the 10GA wire to the positive side of the fan and the other end into the other butt connector I'm using for the ground side of the fan? Do I heat shrink the entire diode? This thing just look like it will melt with any load put on it?

Can someone snap a picture for me? Just can't get my head around it.

THANKS!

I don't think you understand the use of this diode. There is never a "load put on it" in the way that you are thinking.

Google, "freewheeling diode".

Since the motor is an inductive load and an inductor is an energy storage device, when the contacts of the relay open, the energy that is stored in the motor has no place to go. The voltage increases (negatively) and a spark is created across the relay contacts, greatly reducing the contact service life. If a diode is placed (reverse biased) across the motor, it will not conduct in normal operation but will conduct when the relay contacts are opened, thereby supressing the spark. The current is said to "freewheel" through the diode and the motor after the supply current from the battery is interrupted. This voltage spike can get unbelievably high, hundreds of volts for a 12V system. Use a 1N5404 which is rated at 3A, 400PIV.

A diode may look like a capacitor to you, but it's the simplest semiconductor, the basis of the transistor & the CPU. The material you see only surrounds the PN junction. Google that if you want to. This is not a course in electrical engineering (LOL).

Mount it any way you can. It can be on the ends of 10ft of wire. It will carry almost no current. IIRC, I mounted mine under the dash along with the LED indicator. You can heat shrink all, it will never get as hot as the heat gun. You can get 12V LED's ready to go.

There is enough energy left in the fan to light the LED for a few seconds after the relay is opened. Also works with the DCC PWM controller.

Hello. I did not read the thread in its entirety, but wanted to add my two cents.....I have had a black magic electric fan assembly installed on my 92 mustang for years. It was nice clean installation and I have never had any issues with my charging system. They use a temperature probe in the radiator to signal the fan on / off. I wired my to come on even when the ignition is off to keep the engine nice and cool. The system also has the ability to easily wire in a manual on / off switch if you so desire. Very nice setup.

Just to add details of the install....I do not have AC and I installed a larger ford aluminum radiator. Works great.

All I want to add is what ever turns your fans on AND off. Whether it is a sensor or a controller with an infinite temperature adjustment.

The settings must be higher than your thermostat. Basically you want to be driving around with the thermostat regulating your temperature. Like on the highway with lots of airflow coming through the grille. During this time you will be at 190. If your fan settings are at 195 they will not be on.

Now you stop at a red light. No more air flow through the grille. Thermostat is no longer regulating, it's wide open. Temp reaches 195, fans come on and pull the temp back down to 192. Light is green, air flow through the grille and thermostat regulates at 190 and fans will not come on during highway driving.

Basically if you set it too low like 180. Fans will be constantly running because if the temp ever goes under 189 the thermostat will close. Now you have a fan blowing across a radiator that is not flowing water.