What donor car for electric fan swap?

If you don't have a high current alternator, you can forget about using the fan. The stock 65 amp alternator isn't big enough to run the fan and the rest of the car.

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. Now serving. Cost is about $110. 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-$90 See FAN-PWM. Ebay will have the controllers for the $70: 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 current load can burn up the typical cheap automotive switch very quickly. The fan draws 30+amps and you need to use #10 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 isn’t really suited for the job. You’ll have to do a Google search and find your own.

This version of the fan controller will continue to run the fan after the ignition switch is turned off, just like most new cars.
To allow the ignition switch to control the fan so that it does not run when the ignition is off, connect the relay contact #86 to the red/green wire on the ignition coil or to the red/yellow wire on the coolant level sensor.

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 probably as good as 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.

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.

I prefer the Lincoln Mark VIII, the 4.6 Thunderbird (which is nearly identical to the Mark VIII except for how it controls the speeds), and the Taurus/Sable fans. Particularly i like the Mark VIII/Tbird fans.

I have seen some guys use the twin from a contour.

I 2nd(or 3rd) the Mark VIII fan...I've had one for about 5 years, no cooling problems since, it also made my r134 converted A/C be the COLDEST I've ever felt!

2nd on the need for a larger alternator, even my 130 amp doesn't put out enough at idle to charge the battery with the fan on high(underdrive crank pulley).

have had my 50amp for as long as I've had my fan. As statedit isn't that hard, you "can" use a manual switch, I above, you have to remember to turn it on and off, I've never forgotten to do either.

matm347 said:

As statedit isn't that hard, you "can" use a manual switch, I above, you have to remember to turn it on and off, I've never forgotten to do either.

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How do you know when to turn the fan one and off? When you switch the fan on does it run or is it temp controlled? If your just running it when the engine is on how do you know its not running too cool?

I have mine set at 185 with the sensor installed on the T-stat housing so I know the 185 is coming on late but it runs great and with the 130 alt its better.

Thats some good info jrichker - it will come in handy in the future for me!

93 LX said:

How do you know when to turn the fan one and off? When you switch the fan on does it run or is it temp controlled? If your just running it when the engine is on how do you know its not running too cool?

I have mine set at 185 with the sensor installed on the T-stat housing so I know the 185 is coming on late but it runs great and with the 130 alt its better.

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The thermostat controls the engine temp so there's no way I'm runing too cool. The fan pulls heat from the radiator/condenser/oil cooler, so I leave my fan on all the time unless I'll be on the freeway for a while....I didn't realize my 130 amp was too small until I recently put a VOM while@idle and it was @12v...which means I was pulling from the battery.