Front Screen Demister

[Mark1967]

My ML270 (2002) is fitted with a button which boosts air to front screen to provide rapid de misting.

It has developed an intermittent fault where the air does not want to divert to screen.

It seem like an internal vent flap istnt opening/ closing properly.

The only other potentially related thing I have noticed is that my coolant level light came on briefly.

Does any one have any experience of this problem?

 

[Cole@MBS]

Welcome Mark

When you select demist, can you hear the flaps in side the heater box moving, any clicking???

 

[Mark1967]

yes i think i can.

Sometimes the air will direct to the screen then you wil hear like a flop sound and it wants to direct to the cabin vents.

Problem seems to be less after the car has been run for 20 to 30 mins but its hard to say yet if this is a firm charecteristic

 

[popepauljohn]

demister problem

hi
i have identical problem with my ML.....did you find out the problem as i am unsure where to start. any guidance would really help
i switch demister on, only for it to Close" after a second or two and blow the air threw the front vents ?
paul

 

[popepauljohn]

front demister problem

anyone know why my front demister cuts out almost immediately and switches the air to the outer mid dash vents ? i have replaced pollen filter and still no joy....very frustrating with steamed up screen in the mornings. any advice needed, cheers

 

[television]

There is nothing listed for this fault, it does sound like a faulty sticking flap or the motor has a problem.

The only way is to join the car onto STAR and the different functions of the heating can be tested

 

[tanbir17]

after 2min driving i noticed windscreen gone abit misty due to the weather, so i hit the button and i noticed about two third of front screen go more misty and then within seconds it got cleared.

Is this normal?

 

[whitenemesis]

Do you run with the a/c in econ mode (off)?

When you select demist this will force the a/c on and must drive out some moist air first (causing the screen to mist) before the dehumidified air comes into the car.

 

[television]

after 2min driving i noticed windscreen gone abit misty due to the weather, so i hit the button and i noticed about two third of front screen go more misty and then within seconds it got cleared.

Is this normal?

Yes as above,, have you ever changed the filters

 

[tanbir17]

Yes as above,, have you ever changed the filters

Im not too sure, the car was purchase this month and has had full service history since day 1.

When would you recommend i press this button, few mins into drive?

 

[television]

I would take the filters out and check them,, they are not part of any service and seldom get changed.

I think that the problem is worse right now due to all of the rain and damp evenings.

We all leave our air con on all the year round to dry the car

 

[avantdi]

anybody find a solution to this flap issue