Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Fan Speed Knob

Hi,

Easy question for someone who knows.

Does the Fan Speed Knob simply pull off? or is there a grub screw or something I should know about? I have applied some force but thought I'd ask before really pulling.

This is on 2015 Plus 4 GDI.

Thanks in advance.

There is a grub screw that holds the knob on. If you take the dash under tray off you might be able to get to it. The fan speed knob has the same method of fixing as the temp knob shown here.

Thanks John, that's saved me some time.

Definitely a grub screw. Why do you want it off?

I have an idea to replace the 2 speed switch with a 3, but I'd like to keep the original Knob on the new switch so want to take it off to measure up before buying a new one.

If this is possible there would be an additional (spare) position, O would become the 1st On position and be used for a new extractor fan/s, 1 & 2 would be as now.

I've proven the extractor works with a cheap £5 fan, lit a Smoke Match in the passenger footwell and it pulled all the smoke out easily. Just pushing around ideas on how to elegantly implement.

You might get away by keeping the original switch as it has multi terminals but will probably need to drive your new fan via a relay.

I have this little sketch left over from when I was butchering my dash. The switch shaft diameter is 6.3mm



This switch might work?

Worth mentioning that these wafer switches only have a switch rating of around 1A and on the Duratec (don’t know about the GDI) it’s switching the negative side of the relay coil.

That's really useful info, Thanks

My plan is to keep the original switch and knob, but just mechanically limit it to two positions, ON & OFF.

I'll then use it to ground the coil in the forward relay on this inexpensive 12V 60A PWM motor speed controller.



https://www.ebay.co.uk/itm/166609762129?itmmeta=01HQMQ959DHV1B9PRKFCKH68QD&hash=item26cab73751:g:dqoAAOSwr2Zl1ksg&itmprp=enc%3AAQAIAAAA0NKPvzZVtPzZLsrOCjbNAIhC9juse%2FBuvF6yroWAKwSFLIVitNdTy9rC9CI59QucmRzhdnLyLj0ql4CuImguEqYIBbLaxv3jg8EFVRriegVlkgGCLRjDZMQgj8y9jjmMJllRxlq9CgAtQk3TWy6CO6zsFkVN%2FtV0Vht58GGveAT76zpNh8UbbXlOwZPuRrjhTqjWZG0IKyoDFeKfn42%2BYdlngQjgqR8Up9pszALVzXCKTu%2Fzo5Mc%2Bbu3cNHr%2BWLScLnf8u8P8WUzeYiaU7%2FaX%2FM%3D%7Ctkp%3ABlBMUJLVpJe9Yw

All the higher amp rated PWM controllers seem to have a forward and a reverse relay on the board, but obviously I only need to drive the fan motor in one direction.



The controller with its surface mounted relays allows me to bypass the problematic PCB, and with the potentiometer mounted in a convenient position under the dash I will enjoy infinitely variable speed control over the heater fan, from super slow to full blast.

A novel solution. Just make sure that those heat sinks are well. away ( and stay away) from any wiring insulation when it’s fitted into the confines behind the dash. 🔥