[MooLard]

Hi there, has anyone wired up a manual fan switch in their E90 in order to keep the engine temperature exactly where you want it?
If so how? Many thanks in advance,

[hassmaschine]

engine temp is controlled by the thermostat.. not the fan.

[MooLard]

Agreed and I know, what I am trying to combat is on hot days when sitting in slow moving traffic the temp creeps up to the point of the fan turning on and off, I would like to be able switch it on manually to my hearts desire.

[tlow98]

Originally Posted by MooLard

Agreed and I know, what I am trying to combat is on hot days when sitting in slow moving traffic the temp creeps up to the point of the fan turning on and off, I would like to be able switch it on manually to my hearts desire.

I’m confused why you would want to do this? You’ll forget sometime and the car will overheat.

The car is doing a great job regulating itself, already.

[Welcome to NBA Jam]

Is your fan that loud? I can't hear mine.

[RocketSurgeon]

I don't see a manual fam switch being advantageous, but there are a couple ways to do this.
The JB4 has Max Cool mode, which is similar to what you describe.
The fan has heavy power wires going to it with a PWM control wire. If you can figure out what PWM voltage matches your desired fan speed, you could rig up a switch with some diodes and a voltage regulator.
You could also rig up a switch and a resistor on your coolant temp sensor.

[e90yyc]

Abort mission.

You'll cause yourself more headache than it's worth.

[MooLard]

I’m not trying to make it manual only, was keen to add a manual override of sorts.
I was hoping I could just power or earth a wire with a relay to an in car switch, if there was a low power control wire that would of been handy, if there is a special pulse width modulation signal then that would be a tad complex!
Shame, I am partial to a mod here and there, noted that several are stating what’s the point, half of the point is that I like modding my car.

[opjose]

The pwm signals are controlled by the computer/module. They are also timed to provide a power ramp up that gets the motor spinning.

Anything you do will have to interface with the module or you'll end up making things worse.

This is not as easy as putting 12v on the line and calling it a day.

BTW: All of this could be done in software alone but of course BMW never releases source code.

[MooLard]

Opjose thank you for explaining these things to me, I really appreciate the fuller clarifications, I’ll think of a different mod to do..!