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

This really would explain my situation. But why, on a new model would this be something that they would decide is the best thing to do. The fan has two settings, the button has two settings, so who decided that connecting it all up to have 2 speeds was the way forward. I guess I must have just though the slow speed must have just been really quiet and I was just feeling the natural warmth from the vent and assumed it was being blown by the fan.

From my investigation, and I'm assuming under your bonnet is similar to mine, I would remove the gauze filter from onto top of the intake and look for how mane wires you see. Mine had 3 (red, orange and black) and exited on the drivers side and 2 of them connected to two wires from the loom via bullet connecters. The orange joined the green/slate wire, and black to black. The green/slate wire is the positive feed, and when I disconnected it with the red wire that had been cut short, it activated the slow speed.

When I went hunting for my missing slow speed wire, I couldnt find it. When I looked behind the dashboard at the pcv, I couldn't find the green/slate wire either. So it is a big mystery. Good luck in whatever you decide to do, but I'm just going to put up with the fast speed alone as its not worth my time and effort.

Excellent chaps, much appreciated.

Using a PWM controller is definitely a better and safer approach than my heat generating variable resistor idea, and the tip about adding a layer of foam to create a better seal with the bonnet is also great advice, I've observed in the off position my heater still blows very slightly tepid air so I'll definitely try the extra layer of foam to see if it helps?

Much like my TVR the Morgan is proving to be an imperfect animal, however, I celebrate this as over the years I've learnt it's those very imperfections that create character, and fixing the little annoyances builds a bond between man and machin. It's also the very reason I sold my too good, too complete and too fault free Aston Martin V8 Vantage.

Perhaps I'm just a masochist by nature

Thankfully the Talk Morgan forum and the good people who contribute to our self help therapy group is proving invaluable to me, many thanks to you all

As a slight thread drift. Whilst MMC have changed the way the heaters work, every 5 mins it seems. On my car the heater matrix is permanently supplied. The heat is then controlled by a flap. The flap is sealed by a spurious bit of foam that turns to powder. I replaced mine (grey stuff in photo) with Barbecue gasket. But their is a very small gap along the sides due thickness of the gasket. However at least it shuts which it didn’t with the MMC degraded foam.

I removed my PCB and binned it. It basically takes the 4 switch output and sends them via small soldered in relays on the PCB to appropriate device, in my case rear fog light, heated screen, my driving lamps, and hazard lights. It also controls all of the warning/status lights. If i recall its all 5 volt dc logic, wasn't too interested it was getting binned anyway!
The heater fan switch is 2 x 2 speed switches in one, so if one is dodgy you can wire the 2 speeds via the other switch which I did and the blower performance improved (ie you should see 12 terminàls on the back of the switch). I bought 4 new switches from car builders solutions and also a set of LED warning/staus lights (12volt dc), all installed into the existing panel.
One thing that will be required is to rewire the hazard and indicator lights wiring via 2 conventional flasher units which need to be purchesd and installed behind the dash on the bulkhead. I have retained filament bulbs in the brake, side and indicators and rear fog. If you use LED bulbs ensure the flasher units are compatible.
I installed a 36 way terminal assembly behind the dash in order to act as an interface terminal block for the switches and alarm / status lights. If you dont have A/C you can remove the relay that puts the fan on Hi-Hi speed when in use. I recall its the one on the Left in the row of 4.
I didn't revisit the fuse capacities as i hadn't installed any extra loads on the system but I did ensure all fuses were changed to MTA instead of the Chinese garbage installed which are not manufactured to any traceable standards. Oh, take care with speedo wiring.
By the way my car is a 2011 Plus 4.

Dave just remembered to check it and I do have 2 speeds so can’t see why yours shouldn’t have. The stop appears to be missing or broken on mine so it just goes around and round but works fine. I think I would check that cheapo wafer switch out first before committing to any work around. It looks like it might be this one to me?

Dave, Be thankful you don't have the earlier push button sequential switch which adds a logic control level to an even larger and seemingly more unreliable PCB!

It seems highly likely you have a two speed system so fixing the fault would be easiest option. If you are handy with a voltmeter it should be easy to trace.

Asssuming no wiring or connector issues the chain of fan control is Switch -> PCB -> Motor. The switch as Rog suggests may be a good starting point. If your car has same switch/PCB as shown on Rog's pic, all the switch wires are red, but one will be live with ignition on selecting one or other of remaining two according to low or high position.

To help with fault tracing, diagram below of the up to 2014 Plus 4 chassis wiring loom, which I believe covers your car, shows the two miniature relays (shown top left) soldered to PCB (although diagram doesn't identify components on PCB or elsewhere) to energise fast and slow heater fan motor connections.



To save you going cross-eyed note that each relay uses a common feed from a 15 amp fuse (which also powers horn) to provide main power to each relay and to the speed selection switch shown on matching dash wiring, the output of which feeds back to energise one or other relay according to selection. The relevant connections from PCB back to main loom are on the centre of the three 15 way connections shown at top of diagram.

Do you have a link to the wiring diagram please?

Not directly but wiring diagrams are within parts books, downloadable for various models here.