Help, heating controls- resistance issue/bending cables

[bombur]

Hi All, I had time to put back some of the trim after fixing a heating control arm a while back. I thought I would take a peeep at why there is resistance at cold on middle dial and Defrost on 1st Dial (l-R). I can see that the resistance is caused by the cables bending rather than being fed.

This is when dial middle dial is all way to right on hot (1.) and on feet/face (2.)

This is when middle dial is all the way to the left on cold and there is a lot of resistance, you can see the cable bending (1) also when I move dial to defrost, it doesn't want to get there and you can see why (2)

What have I done wrong putting it all back and what are my options to sort?

 

[bombur]

Also a video to better explain. First dial move is going from hot to cold, second is control dial going from face to feet to defrost


Z3 Heater control resistance

 

[Rudyrov]

I would start by making sure that the control cables move freely and are well lubricated.

 

[bombur]

I would start by making sure that the control cables move freely and are well lubricated.

So lubricate them from behind dash as they go into their plastic tubes?

 

[Rudyrov]

So lubricate them from behind dash as they go into their plastic tubes?

I have never had to do my cables but perhaps I should since a quick trip out to the car showed they seem to be somewhat stiff. I have a motorcycle cable lubrication tool that I think I will try, it is a metal clamp with a rubber inner section that fits around the cable, this allows the lubricant to be force-fed through the cable from one end.
At least in my case, that what I am going to try.

 

[t-tony]

Difference being bike cables are made from Bowden (multistrand) wire cable and Z3 heater cables are one solid wire?

Tony.

 

[Rudyrov]

Difference being bike cables are made from Bowden (multistrand) wire cable and Z3 heater cables are one solid wire?

Tony.

Hi Tony, Agreed and some bike cables now have Teflon liners and are said to not need lube.
As I said above, I have never had to lube my Z's or any other BMW's heater cables so I am somewhat in the dark here. Do you think the BMW cables are of the non-lube kind?
Additionally, those solid cables most likely do not take kindly to being bent as they are in that video, I wonder if that is an issue at this point?

 

[bombur]

I have used a long nose pliers to help guide them to go in properly without bending. But I fear a continued issue. Will leave them all the way in (defrost and cold) overnight and see if that helps.

 

[t-tony]

Thing with solid single wire cables is they’re meant to push and pull. Whereas a Bowden cable (in general) is only designed for a pulling motion against spring pressure to make it return. If solid wire cables get a “kink” in them it makes their operation difficult usually in one direction more than the other. I don’t think lubricating them will make much difference tbh. I think the OP has possibly got a twist in the “outer” cable . Having been in the same position for many years they they take on the shape they’re in and object if they’re not put back in the exact same position. Hope that makes sense.

Tony.

 

[bombur]

Yeah they are kinking a bit, any remedy to lose the kink permanently?

 

[Rudyrov]

Yeah they are kinking a bit, any remedy to lose the kink permanently?

I can't think of any way to alleviate a kink in a cable, I would look for a custom cable maker perhaps, and seek out advice from somebody who specializes in that area of the car.
Alternatively, I would replace the cable if it's available or find a "kindly-used" cable with no kinks.
FCP Euro seems to cary the cables, at least for a 98 z 2.8L

https://www.fcpeuro.com/BMW-parts/Z3/Heater-Control-Cable/?year=1998&m=86&e=179&t=6&b=10&d=65&v=

 

[t-tony]

Yeah they are kinking a bit, any remedy to lose the kink permanently?

Disconnect one end and try twisting the outer and reconnecting and see what happens.

Tony.

 

[bombur]

Disconnect one end and try twisting the outer and reconnecting and see what happens.

Tony.

Thank you but that sounds simpler than it would be for me most probably!. I know one end is attached to the the control arm, not sure how to disconnect without removing the whole unit? Is it possible? Where does the other end go to?

 

[t-tony]

Have you had the cables disconnected at all? I've not had first hand experience of Z3 heater cables, just going on various cars that I have had over the years. I suspect the best thing is to look at one which is working correctly and try to spot the differences.

View: https://www.youtube.com/watch?v=AVyaVq6leRw

View: https://www.youtube.com/watch?v=wse605NE2_c&t=14s

View: https://www.youtube.com/watch?v=NNKJYZxeYDs


Tony.

 

[bombur]

Thank you @t-tony yes I removed the heater controls and disconnected the cables to fix one of the arms, was a b of a job and one i dont want to repeat. Wonder if when I put the cables back I twisted them 180 degrees so they are in the arms incorrectly. If thats the case and I do twist them round will it be resolved or have I b******* the cables?

 

[t-tony]

Possible you may have twisted the cables, it won't have b******* them but maybe that is the problem.

Tony.

 

[bombur]

I have tried them this morning and both are working much better. No kink if I go relatively slowly. Tried a number of times all way to left and right on both dials. So 'force' feeding it through, trying to counter the bend and a bit of lube all helped I think. Thank you @Rudyrov and @t-tony. I have also discovered I do not need to remove the glovebox etc to get at it if it happens again, which is a big plus!

 

[t-tony]

That’s good news, hope it’s sorted!

Tony