W124 No demist function again

[GP801]

Dont seem to be having a lot of luck lately with the 124. Following on from the new oil filter unit it needs a tensioner pulley for the serpentine belt. Not a big job but now the demist function has given up again. No air to the screen. It can be directed to face level or floor but nothing at all upwards. This is the third time this has happened. 2010 it was stripped out and the cables reattached to the flaps. It was then ok for about 6 months and the same thing happened again so in 2011 all taken apart and new cables fitted. Its a dash out job every time and has been done by the main dealer - not cheap but at least the second time they only charged for the parts used. Its now going back to them once again. Its just outside the 2 year repair warranty but I think that will not be a major issue. Anyone with any bright ideas as to why this keeps happening or how to stop it. Much as I love the 124 I am getting a bit disillusioned with it now.

 

[jaymanek]

Its a fiddly job but they are just cables on levers, cant see why they would keep popping off!

 

[GP801]

A quick update. The cables have snapped where they join on to the flaps. The connectors have broken away and they cannot be re attached. New cables needed. Exactly the same thing that happened last time. Begs the question why? There is nothing obvious fouling them. Only thing we can come up with is that there is a problem with the air flow direction controller putting extra stress on the cables. Going to replace the controller whilst its all apart.

 

[isobars]

Hi,

Any work-around to avoid dash removal?

Cheers,

Paul

 

[GP801]

Dont think so. Its not back yet. Should be this week sometime. Also having service, MOT and new belt tensioner pulley/belt as its become quite noisy.

 

[GP801]

Resurrecting an old thread but its gone again! No air to the screen vents. Or for that matter the centre dash vents. Whatever the dial is set to there is airflow to the side vents and also flow to the floor if that is selected. No demist though. I am in Italy at the moment and am due to drive it back to the UK later this week. Will be talking to the dealer tomorrow to see what they have to say. its within the 2 year period so hopefully they will cover the cost. At least the weather forecast is decent so hopefully can get it back home without needing the demister. Any ideas why this is happening and how to prevent it recurring?

 

[smurgewurfler]

Is it possible that the cable length is badly adjusted so that when activated it is putting too much strain on the fitting on the flap and breaking the thing?

 

[GP801]

Is it possible that the cable length is badly adjusted so that when activated it is putting too much strain on the fitting on the flap and breaking the thing?

I think the cables come from MB complete with the fittings attached. Last time they also changed the control thingy in case that was putting strain on the cables. It is booked in for the 29th so we will see what transpires. I am wondering if its possible to fix the flaps open so there is always flow to the screen. At least the dealer has confirmed that its down to them as its within 2 years.

 

[hotrodder]

The cables have preformed ends but i believe (possibly wrongly) cable tension is adjustable? Was the air direction control stiff and/or stiffer when selecting demist?

 

[GP801]

The cables have preformed ends but i believe (possibly wrongly) cable tension is adjustable? Was the air direction control stiff and/or stiffer when selecting demist?

No. It always seems to be fine.

 

[GP801]

Another update. Exactly the same issue. The cables have snapped off at the connector again! They tell me there is no undue tension on them. They dont think they can be adjusted in any case. Plan is to order new cables from Germany but in the mean time to fix the flaps open so that at least I have a demist function until the new parts arrive. Cant say I am confident that this will be the end of it but you never know.

 

[219]

A quick update. The cables have snapped where they join on to the flaps. The connectors have broken away and they cannot be re attached. New cables needed. Exactly the same thing that happened last time. Begs the question why? There is nothing obvious fouling them. Only thing we can come up with is that there is a problem with the air flow direction controller putting extra stress on the cables. Going to replace the controller whilst its all apart.

I know it isn't much help , but I had my first 124 almost from new and kept it for 11 years and 200,000 miles , then several others since , although not for that length of time or mileage , and I have never heard of this happening !

I wonder if you have just been very unlucky , or is there some other root cause which has not been identified ?

 

[GP801]

There has to be a reason. They say the flaps in the heater box move freely and there is no undue tension on the cable. The plan is for them to keep it for 3 days and to keep working the controller regularly to see what happens. At the moment its set so that air comes out of all the vents simultaneously. It would not be a total disaster if it had to stay that way. Whilst its in they are also changing all the seals on the differential as they are weeping quite badly.

 

[hotrodder]

Bizarre. Shot in the dark without taking one apart (not on a list of things i'd want to do) or studying drawings but if they keep breaking at the flap end i'm wondering if there's supposed to be a spring or bush to 'damp' the flaps and/or something to limit their travel and if so whatever it is has broken/gone awol allowing the flaps to, err, flap about a bit (vibrate) and fatigue the cables? I'm guessing it can't be as simple as the cables have been routed incorrectly if that's even possible?

 

[GP801]

Bizarre. Shot in the dark without taking one apart (not on a list of things i'd want to do) or studying drawings but if they keep breaking at the flap end i'm wondering if there's supposed to be a spring or bush to 'damp' the flaps and/or something to limit their travel and if so whatever it is has broken/gone awol allowing the flaps to, err, flap about a bit (vibrate) and fatigue the cables? I'm guessing it can't be as simple as the cables have been routed incorrectly if that's even possible?

Like you I am struggling to see why it keeps happening. The cables are not expensive - £15.00 for the set last time. My understanding is that they come as a complete unit with the fittings attached and are not tweakable. It may be how they route them but I don't think there are many options for that either. If it happens again I shall have them set it up as it is now. No cables and all the flaps open.

 

[GP801]

Well its back. New cables yet again. They say everything inside is as it should be. No fouling of cables, flaps move easily and controller is fine. Extra lubricant added allegedly. We will see what transpires. At least no cost attached to this although did have the differential seals changed as they were leaking significantly.