Heater rotary switch

[pgoldsmith]

Does anyone know how to remove the heater knob / rotary switch?

Mine is stuck on no.3 setting (highest), so I’m trying to remove the switch to investigate further / replace.

I’ve managed to remove the outer frame, so the whole piece is free apart from the heater cables being still attached – feel loathed to disconnect these as the plastic being over 25 yrs old will almost certainly break.

Not sure if the black knob comes away from a spindle and also cant see how the switch is held in place.

Any pointers will be greatly received.

Thanks
Paul

I had to do the same to my car, pain in the ass job had to remove loads of screws and centre tunnel etc

Not sure if the black knob comes away from a spindle and also cant see how the switch is held in place.

Paul ..... I take it you have manoeuvred the panel to a position above the console ..... The knob should pull straight off where you should find a nut around the shaft housing which when undone you should be able to withdraw the switch from under the panel.
The knob could be quite tight on the shaft as it has been there for quite a while. If you can't pull it off, you might have to lever it off ...... I use a pair of long nosed pliers, each nose either side of the shaft, and gently lever the knob off being careful not to mark the panel.

[pgoldsmith]

Thank you.

I applied some warmth via wife's hairdryer and, as suggested, carefully prised the knob off.

Looking down at the top there appears to be a collar with 6 notches. Is this the locking nut you're referring to ?
There are also six notches on the outside of the hole - I guess this is part of the top assembly.

Tried using some long nose pliers to move the collar anticlockwise, but it's very tight and I want to be sure I'm doing the right thing before I snap anything - .everything is so fragile nowadays.

Paul

not what I was expecting ......
looks like you need to get it out to get behind the trim panel.
There is a screw in the storage cubby hole next door which needs to be removed first.

[pgoldsmith]

Simon,

Yes I've removed the small screw in the adjacent compartment, so the only thing preventing me from taking the whole thing out are the heater cables. Bit loathed to do that though, as they're only attached on small plastic pieces.

I had to do the same to my car, pain in the ass job had to remove loads of screws and centre tunnel etc

So Jango, did you have the same type of switch and if so did you turn the collar (with the notches) ?

Mine is a 1991 so perhaps may be different than earlier versions.

[pgoldsmith]

An update.

Finally managed to remove the heater rotary switch.

In my case, the collar turned out to be a part of the switch itself. i.e. it was not a threaded locking nut. It was a type of push fit which I’m guessing required a special tool with six prongs to squeeze the collar and allow the switch to be removed.

See attached photo.

Unfortunately I ‘roughed up’ the collar in my determination to remove said piece.
It’s not too badly damaged, and my aim will be to replace it anyway.

Markings on the switch are SOFICA BREVET which is probably a French manufacture that’s no doubt long disappeared.

So, if you encounter your switch stuck solid and need to remove it and it looks like my previous posted pic, try to squeeze the collar on all angles to remove it.

I didn’t need to remove the tunnel or the heater cables in the end.

[pgoldsmith]

Probably this is aimed more at John in Jersey, but does anyone know what current flows through this rotary switch? i.e. is it the same current level that drives the fan (20 / 25 amp) or is it mA and goes through a relay ?

Paul ...... From what I can understand from the manual, the switch carries the current direct to positions 1-2-3 of the switch to the fan, but via a couple of series resistors to vary the speed from slow to the position just before full speed, then the switch operates a relay only for the high speed position drawing the max current, but I don't know what the max current drawn is, but it will be fairly high.
Clearly the original switch was capable of carrying the lower currents for the lowed speeds via the series resistors, but could not carry the current for the full speed, hence the relay.
This does make it difficult to get a replacement switch to do the job.
It might be worth seeing if anyone has a spare panel with switch from a breaker Alp as the easy option in the first instance.
I hope this helps.

John

[pgoldsmith]

Thanks John. I have now measured the current drawn on all three positions 1,2, & 3.
Position 1 draws 4 amps
Position 2 draws 7 amps
Position 3 draws 0.1 amps

This confirms your comment that position 3 (the blower on high setting) switches through a relay.

Below are some photos of the innards of the switch – turns out to be a very primitive arrangement. Mine was stuck in position 2 and looks as though the bottom of the shaft was locked solid for some reason.

I managed to buy an identical replacement from a auto specialist in Germany – it was a pure fluke - advertising on the German eBay website.

However, what I’ll try to do is source a suitable replacement which is of a higher quality – as I’m sure I wont be the last casualty of a stuck blower switch!

I have now measured the current drawn on all three positions 1,2, & 3.
Position 1 draws 4 amps
Position 2 draws 7 amps
Position 3 draws 0.1 amps

Hi Paul,
The switch is actually a four position switch ...... basically 0-1-2-3. ..... You are right with you above quote for 1-2-3 positions, but although "0" position is in fact the apparent "Off position" of the switch, as well as 12v feed being fed to that position, there is another 12v unswitched feed being sent direct to the maximum resistance of the series resistor assembly and then on to the motor, which means that in the "0" position of the switch, the fan motor will run at its lowest speed anytime the ign is switched on, maintaining a small air flow into the interior of the car. This is done because there is no ram effect for the air when the Alp is on the move because the air intake for the ventilation/heating system is facing the rear of the car.
With the switch in the "0" position, you should just be able to hear the fan running at a low speed.
This will not help your sourcing a new switch, but it might be useful to know how it all works ...... if you did know this already, please disregard this post.

[pgoldsmith]

John,

Yes, I was aware of the basic function. I didn't count the resting position, but you can take that view

What I need to find is a similar switch rated at max 10 amps that we can use. Any ideas?

Rgds,
Paul

What I need to find is a similar switch rated at max 10 amps that we can use. Any ideas?

First quick look at Farnell but only if there is sufficient depth below the panel.

http://uk.farnell.com/schneider-electri ... dp/2614757

I will see if I can find anything else.

PS. This might be a better bet ......... Max 15 amps at 12v, through panel mount.

https://www.amazon.co.uk/Position-Purpo ... B00EPFKMTU

You may have to make up an adapter plate to fit under the panel to accept the different switch fitting.