Morris Minor Owners Club

Well it appears that it’s the switch that’s gone and not the motor.
Looking at the switch, it’s virtually black inside and full of fluff. I tested it with a bulb and battery and it smelt hot to say the least.
So in the bin with that one.
Anyone know what the type of switch is and from where I can source one?
I assume it’s just a variable resistor switch, but not 100% sure

The switch is called a Rheostat and they all appear to be around the £37 to £50 mark.
Try these:

https://www.ebay.co.uk/itm/HEATER-FAN-R ... SwiSZdLZqH

https://www.ebay.co.uk/itm/RHEOSTAT-SWI ... SwF5tbbblQ

https://www.ebay.co.uk/itm/Land-Rover-S ... SwUP5b509F

https://www.ebay.co.uk/itm/CLASSIC-LUCA ... SwlEJc~VaQ

Best wishes,
Mike.

or

https://www.ebay.co.uk/itm/New-old-stoc ... Swl7NdMIcf

At that price I would just fit a pull on/off switch. The fan hardly does anything even when on maximum setting, so the rheostat is really not needed. Might be worth taking the old one apart before you bin it though.

cadetchris wrote: ↑Thu Sep 19, 2019 3:34 pm
Looking at the switch, it’s virtually black inside and full of fluff. I tested it with a bulb and battery and it smelt hot to say the least.

A 1940/50s technology rheostat (older than that probably) is quite basic and you've probably got a good chance of repairing it.
Is it open case? i.e. can you see the winding around the (probably ceramic) former?
Can you see a break in the winding?
However...
Did your bulb light?
If it 'smelt hot' then it's not open circuit, it can only 'smell hot' if it is actually allowing current to flow which is heating up the fluff and dust in it.
If current is flowing, then it may just not be enough current for the motor to start running; the winding surfacemight just need cleaning.

A good photo or three of what you have got would help considerably.
I don't suppose you've got a multimeter? If you haven't probably a good idea to get one; they start from about £6 on Fleabay.

mobylette wrote: ↑Thu Sep 19, 2019 5:19 pm At that price I would just fit a pull on/off switch. The fan hardly does anything even when on maximum setting, so the rheostat is really not needed. Might be worth taking the old one apart before you bin it though.

I can't vouch for the Smiths one, but my Tudor is a darn sight more use than your description....

There's a heater currently listed on ebay:
https://www.ebay.co.uk/itm/CLASSIC-SMIT ... Sw6ZFdfnBA

From looking at the images with that listing, it looks to me as though the rheostat would easily come apart for cleaning. In fact the listing for this item actually states

The original rheostat has been checked and cleaned and it turns smoothly with the original speed control knob.

So I would seriously refer you back to my earlier post about cleaning it.

I’ll open the switch tomorrow and have a good look and a clean out.
Having looked at replacements, it seems financially worth my while to repair it.

Right, switch has been opened and cleaned out thoroughly and works like a charm.
One slight concern though, is it meant to get hot or at least warm to the touch? The switch that is, the heater is expected to get warm.

Assuming you have hot water flowing through the heater, and hot air blowing out from it, the switch is bound to get at least warm.....

if the blower is working now, then I would hazard a guess that what you are feeling is the effect of the resistor (rheostat) taking some of the energy... It's normal to get warm in use.

Think of the circuit as being 12v going to the heater rheostat, then the blower motor, to return to the battery to complete the circuit.
You are controlling the speed of the motor by sharing the energy in the circuit between the motor and the rheostat.
if you take more of the energy in the rheostat, it's going to dissipate it by getting warm; I'm guessing the rheostat has a ventilated casing?