My 2012 +4 has one too, I can only assume Morgan wanted the low & high-speed feature for refinement, i.e. lower fan noise on low speed? A big old resistor like that is a very old school idea that in my opinion only serves to introduce a potential point of failure, these days you’d use PWM to give a temp referenced and infinitely variable fan speed arrangement.
Admittedly Monty does have a seemingly very efficient Mulfab aluminium radiator, but my EMU Black ECU logs show super stable coolant temps within a very tight operating range from 83c minimum even when driving at speed on a cool day, to 86c in stop start traffic on a warm day.
If like me you're more familiar with a traditional arrangement, the thermostat system on a Duratec is a bit unconventional, but it clearly works well as my temp logs prove. The setup seems supremely adept at regulating coolant temperature, and largely without the need for assistance from the rad fan.
My ECU triggers the high-speed fan relay only, I've set activation at 93c, even idling in traffic on a warm day it takes some minutes before the coolant reaches my trigger temp and the fan chimes in, under normal mixed driving conditions including some town driving it's quite common to never experience fan activation at all.
Monty's cooling system is clearly very under stressed and superbly well regulated by the Duratec thermostat system alone, I’m seeing an extremely rapid warm up phase and consistantly that nice tight 83 - 86c operating range, and all this with very infrequent fan assistance required. Given my data supported experience, I can’t help feeling Morgan’s low speed idea is an unnecessary complication. Old-school big resistors like the one shown are also a point of high heat and ultimately potential failure, the thing clearly gets so hot a heat shield was deemed nessesary, for many reasons that's far from ideal.
I also have to say on the rare occasion my high speed only fan does chime in, it really isn’t that noisy anyway, and with fan-on time so short anyway (10-15seconds max) I just don’t see the point of triggering the low-speed circuit.
Last edited by Montegue; 02/09/25 06:38 AM.
