What's this switch?

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Jenko
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What's this switch?

Postby Jenko » Mon Apr 15, 2019 12:10 am

Hi,
Help out a newbie!
There is a switch on my 1968 saloon, under the speedo, bottom right corner. It slides left and right, only 2 positions.
It seems to switch off the two orange lights on the speedo, but what is its purpose?

Also, can anyone tell me which position of the heater switch is for "demist"?
Thanks

Bowie69
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Re: What's this switch?

Postby Bowie69 » Mon Apr 15, 2019 12:22 am

Mystery switch is for night driving when in the wilds, stops the gauge lighting from ruining your night vision :)

Jenko
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Re: What's this switch?

Postby Jenko » Mon Apr 15, 2019 12:26 am

Thanks Bowie.
Any info on the heater switch setting?

GavinL
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Re: What's this switch?

Postby GavinL » Mon Apr 15, 2019 9:09 am

Apart from making night time driving more fun ( I remember driving up the A697 to Edinburgh at night in a Midget, dash lights off, Ultravox turned up loud :) ), apparently it was so that you could turn the dash lights off when leaving parking lights on, to reduce battery drain ( how many people know that the highway code requires all vehicles to display parking lights when parked on a road or a lay-by with a speed limit greater than 30mph, or any road in fog?).

simmitc
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Re: What's this switch?

Postby simmitc » Mon Apr 15, 2019 10:34 am

You mention two orange lights. That suggests that the bulbs to illuminate the speedo may have been placed in the holes for the warning lights. The speedo illumination lamps should not be directly visible, they spread light around the edge of the dial. With the speedo removed, you will see that there are lamp holders for illumination that should have red or red/white wire going to them, plus warning lamps that will have green/yellow (oil), white (ignition) and blue/white or sometimes plain blue (main beam) but it's easy to fit the holders to the wrong holes.

The above aside, the switch should, as stated by others, illuminate or extinguish the speedo illumination.

On a standard car, the heater blower is either on or off. It's the silver switch mounted on the heater casing, centrally below the speedo. There is also a lever that moves vertically to deflect the air flow. Bottom = off, middle = screen (demist) and top = cabin which still sends some to the screen as well.

If the car has been modified then the arrangement could be different - a photo will clarify things.

cococola
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Re: What's this switch?

Postby cococola » Mon Apr 15, 2019 12:23 pm

I learnt all about this switch 4 minors ago when I spent ages trying to trace why my speedometer never lit up :-? Very embarrassed when I found out :D :oops:
Morris Minors..... such fun :D

simmitc
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Re: What's this switch?

Postby simmitc » Mon Apr 15, 2019 4:00 pm

Another thought: if you can see the switch for the heater blower but cannot hear the blower running with the switch in either of its two positions, then you have a separate issue. The fan works only when the ignition is on.

bufferzone
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Re: What's this switch?

Postby bufferzone » Tue Apr 16, 2019 9:02 pm

One more thing, the orange light on the left is not operational on a black speedo for 1968, only the right orange for oil pressure and the red below it for ignition and the little switch should not turn these off. :D

Jenko
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Re: What's this switch?

Postby Jenko » Thu Apr 18, 2019 4:46 pm

Thanks.
Once I get my Dynamo problem fixed, see seperate thread, I'll get to grips with these orange lights, and speedo light.
Not sure what's going on with my heater, it blows hot, really heats the car well, but demist is rubbish!
It is 51 years old, so I forgive her.
Stripping the speedo to solve a dodgy light problem, then finding out there is a switch! 😃 Brilliant. That's the sort of muppetry that happens to me too!

simmitc
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Re: What's this switch?

Postby simmitc » Thu Apr 18, 2019 9:15 pm

If you've got a heater that really warms the car then I'd try sell the recipe :o

As the fan is working, the lack of demist is probably going to be either a blocked vent or more likely a disconnected hose. There should be a wire reinforced hose, about 1.5 inch diameter, running from either side of the heater up to the screen vents. As someoine has previously obviously fiddled with the speedo then the hoses might have been dislodged. They are easy to access with the gloveboxes and/or speedo removed. If the vents are blocked, for example with fragments from a broken screen or general debris, then you'll need a stubby or angled scredriver to reach the screws on top of the dash, unless the screen is out which makes access to the screws very easy.


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