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

I can confirm the 2014 on Classics use a ground trigger from the same heater fan switch to trigger their BCU Rog.

Once again, I am so glad that these sort of new fangled devices are not fitted to my 4/4.


Bud
4/4 - Stanley

When re-wiring your one position fan switch make sure this offers high speed connection on fan motor to controller Dave. This would be green/yellow wire to motor to allow full speed range.

I was amused to recall yesterday travelling in my near 60 year old Land Rover on which I was able to precisely adjust heat with it's heater fan rheostat

Hi again,

Electrics were never my forte, but have been reading up and think I understand the reason why a Relay is required if I want to use the same/similar switch. So I think I need a 4 pin Relay set up like the diagram below, please someone confirm or set me straight.



I would take the live feed from the Fuse box and the "Light" would be my Fan.

Also...

Does anyone know if the existing switch can be made into a 4 position, there seams to be lots of unused connectors on the back, or do I need a replacement?

That would work Mark but only for a single fan speed. Is the relay setup for your extractor fan though? If so it may be this small fan is within current rating of present switch contacts.

Not sure what you would do with four fan switch contacts either since the main motor is only two speed

Hi Richard, thanks for this

The extraction fan will be a simple single speed, it's either on or off.

I'd like to use the same/similar switch to ensure I never have the Extractor and Heater fans on at the same time.

Positions explained a bit more.

- Position 0 would be Off.
- Position 1 would provide the earth for the new extractor fan circuit,
- Positions 2 provides the earth for the current Heater fan 1
- Position 3 provides the earth for the current Heater fan 2

If this pans out and I reuse the existing Knob and markings on the dash then I'll rotate the switch anti clockwise so that Off will be left of the current O (Off) position, O will be position 1 (Extractor) etc,

I will need at least a 4 position switch, the back of the one pictured looks like a 12 position switch so I was wondering if it was limited to just 3 somehow that could be changed.

Thanks Mark I understand better now. As said it may be you don't need relay for extractor fan. That switch is definitely built for multiple poles so the only issue would be moving the mechanical stop assuming it's that simple.

IF you should choose to use a relay, good idea to use one which has a flyback diode incorporated across the relay coil. This will minimise voltage spikes which could damage the ecu. They cost little more and, if you find one day that a relay has failed on perhaps your fuel pump, then this one could be borrowed to plug in to get you home.

Yes I think that you will need a new 4 way switch. I believe the switch at the moment is a fixed 3 way, with 4 poles (so 12 positions total). It only uses 1 pole so will have 3 poles free but I don’t think that will help you. The stop can be adjusted to limit the rotation.

Enclosed versions are available Doug




This 30a ventented enclosure version would be my preffered choice.