Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Loss of heater fan speed

Thanks chaps, all very helpful as always

Much appreciated, Dave.

Update, I now have both the slow and fast fan speeds instead of just fast

I say I now have both fan speeds, in truth I only get the slow and fast fan speeds with the heater control moved to the second click i.e it's highest setting, with the heater temp setting on low (first click) the fan still runs fast as before and no matter which of the two fan settings I choose.

Actually it all works surprisingly well as I've ended up with the following five settings that incrementally deliver more warmth:

1. Heater and fan off

2. Heater on low, fan off

3. Heater on low, fan on setting one, like this fan the fan runs fast on both settings so I just leave it in setting one

4. Move the heater one more click to it's high setting but the fan still in setting one mysteriously the fan now drops to its low speed setting

5. With the heater still in setting two now move the fan to setting two and the fan runs fast

The return of the two distinct fan speeds in the highest heater setting seems to have come about since I added my front fog lights and connected them up using the front auxiliary wiring Morgan provided within the loom..... go figure

The heat control knob is notoriously stiff, and actually has more than 2 clicks. All that it does is to rotate an indented quadrant which in turn drags on a bowden type cable which opens a flap, mechanically. No electricity involved. When you next remove the dash, give the quadrant and cable a small squirt of lube and you should find that it is much easier to operate and will go round for at least 4 positions. The combination of variable flap with the same speed may make it seem like varying speeds, due to the volume of air that is let through as the flap is further opened.

Just to add to my post above, in case of any mis understanding. The fan SPEED knob has only 3 positions: off, low speed and high speed. If it is forced, it will break off the internal stop and will then go round in a complete circle, but will still “work”.

To illustrate Doug's description Dave here is an image of the back of a dash. 3.7 Roadster in this case but the purely mechanical heat control is the same.



The knob at front of dash turns the toothed wheel shown (bottom left of centre) which engages with a series of radial holes on a pivoted quadrant located at right angles (shown end on above with pivot nut). This in turn operates on a Bowden cable to open or close the remote heater control valve. There are a further series of radial holes which provision for a ball detent to allow several click positions between heater valve fully open or closed.

Strangely on my Roadster and others it seems this ball detent is missing

The fan control switch (bottom right of centre) has multiple positions but is limited by detent to just three as per Doug's caution above. You can see the three wires leading from it to give just two fan speeds plus off.

You can hopefully see therefore there is no electrical or mechanical connection between heat and fan control.

Note there are four heater duct outlets the settings of which may change the perceived fan speed.

Interesting

The heater control is indeed stiff but I've only ever had two clicks out of it, pushing it any further feels like it might break something so I've chosen not to force it. It would be helpful if someone could confirm how many clicks I should actually expect from the heater control knob with a free moving mechanism, is it three, four or more clicks when the system is working correctly?

I have to say to the ear the fan speed change is very distict, it definitely sounds like a two speed fan running slow and then fast but I only hear this change with the heater knob on its second click. I guess it's possible I am getting both speeds in both heater settings after all, but I just can't hear the speed change until the heater control flap is opened up a bit further?

I have to say it would be helpful if Morgan had put some increment markers on the fan and heater knobs!

As it stands with no markers on the knobs for all I know the fan may have more speeds than two, and as I've already said the number of heater settings remains a mystery to me too. However, by the look of these images I took from an advert selling a 2016 Plus 4 it seems MMC too it upon themselves to add some control knob markers on the last direct injection engine equiped cars.




If my 2012 Plus 4 has the same number of settings as the later car the above images seem to indicate I do indeed have two fan speeds, but I may actually have a whopping five heat levels to choose from!!!!!

Perhaps someone with a 2012 Plus 4 like mine could help clear this up for me?

My 2011 Plus 4 Sport had the same dash, but no markings around the heater control. I think it went from “off” and clicked around to 4 heat settings.

Edit - sorry, it wasn’t the same layout, but the same heater knob/control!

I would only add Dave that the heat control is mechanical and with possibly a random number of discreet position clicks depending on how Bowden cable is fitted, or indeed none at all as on my Roadster if they have left the ball out. FWIW no position markings on my later car either. Although slightly stiff its pretty obvious on mine where fully open (clockwise) and fully closed are. Typically for adjustment I move it 20 - 30° at a time out of a total range of around 120°.

The fan control switch however has obvious detents to allow three positions running clockwise from off, low, high fan speeds. Please do not even dream of forcing this switch further, there are only two speeds!

Hope this helps.

My 2009 Roadster does have detents to both controls. But with no markings on the dash I referred to the Manual:

9.2 Temperature Control To control the temperature of the air being supplied to the cabin, rotate the knob located on the instrument panel. Turn the knob clockwise to increase the temperature of the supplied air and anti clockwise to reduce the temperature of the supplied air.

9.3 Fan speed A 3-stage switch located on the instrument panel controls the rate at which air is supplied to the cabin. The fan can be set at zero fan speed, low speed or high speed.

I love "zero fan speed", aka "OFF".

When I had the dash out this summer, some white grease sorted the action of the temperature control mechanism.

My +4 is Feb 2011 build.
It has got the ballbearing indents and as well as Off, has 4 additional clockwise positions, finishing at 6 o’clock. It will go a little past that but without clicking into position. It’s positions 3 & 4 that really allow the heat to belt out. As Richard says, how many positions. you have will somewhat depend on how the Bowden cable was fixed, with how much slack, etc. Despite lubrication, the first two positions are a little easier to rotate than the second two.