Spal Fan Wiring Question

[Adrian_Visser]

Has anyone wired up an aftermarket fan to run on two speeds like the stock aux fan?

If you were to remove the resistor pack and wire it up to the aftermarket fan the same way as stock shouldn't it run the same way as the stock aux fan?

I have a 2360cfm Flexilite fan that I'm going to try and wire this way. With the lower temp 80/88 degree switch of course. The recommended fuse for the Flexilite fan is 20 amp so the the 30 amp high speed circuit will be more than enough.

[bimmerteck]

Has anyone wired up an aftermarket fan to run on two speeds like the stock aux fan?

Yes.

If you were to remove the resistor pack and wire it up to the aftermarket fan the same way as stock shouldn't it run the same way as the stock aux fan?

if you remove the resistor, you will loose low speed as that is what it is installed for. ;) To wire the fan the same as stock, it will need a resistor, just like the stock fan has.

[AndrewBird]

I recommend powering the fan from a constant source rather then switched. This way the fan will run after the car is turned off until the temp is cool enough for it to turn off. IF you run it switched, then it will turn off with the ignition.

Also, to run an override switch, just run one terminal of the switch to ground then the other to the same terminal that the thermo switch is hooked to.

[BMWTurbo]

OP probably null and void now, but you could use a pair of diodes on the temp switches outputs (If in fact teh temp switch does drop continuity across the 'low temp' switch when the high temp closes). This will mean that you won't get any cross talk between the outputs and everything will operate as per factory, but you'll be able to switch the thermo on with the lower trigger point.

I'm personally not a fan of constant feeds to fans as they 'can' switch on by themselves and kill your battery. An engine fan stops when the engine does, so why would a thermo have an issue if it stops with the engine also.

[Adrian_Visser]

Yes.



if you remove the resistor, you will loose low speed as that is what it is installed for. ;) To wire the fan the same as stock, it will need a resistor, just like the stock fan has.

Allow me to clarify, I meant remove the resistor pack from the old aux fan and wire it to the new aftermarket fan

I recommend powering the fan from a constant source rather then switched. This way the fan will run after the car is turned off until the temp is cool enough for it to turn off. IF you run it switched, then it will turn off with the ignition.

Also, to run an override switch, just run one terminal of the switch to ground then the other to the same terminal that the thermo switch is hooked to.

What's the point of having the fan run when the car is off though? all you will be doing is cool the radiator since coolant is no longer flowing through the engine.

[CincinnatiKid]

Allow me to clarify, I meant remove the resistor pack from the old aux fan and wire it to the new aftermarket fan

Could you not just run the #85 wire to High and Low temp, that way the fan would switch on at both temps?