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Discussion Starter · #1 ·
Hi,

There doesn't seem to be an 'introduce yourself' section on here, so here goes. My name is Clive and I am new to Mercedes, and to the ml 270 that I have just bought. I have drive Toyota 4x4's for a few years but it is time for a change.

The current problem, or one of them, is that the AC control in the back does nothing. The power windows work fine from there so I am assuming that the wiring is OK, I have had the top of the console out and the loom is plugged in at both ends. Could there be a setting somewhere that disables this control? I have tried turning off and on aotu from the front, I have also tried enabling and disabling the rear ac from the front. All of this still leaves the rear control doing nothing. Thanks for looking.
 

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Outstanding Contributor
2006 ML500 2002 ML320
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You do indeed have a 2002 ML. Any ML built after 9/30/2001 is a 2002.

If your AC/Heater controls look like the photo below, there is no doubt it is a 2002.

If you have a 2002, PLEASE UPDATE YOUR PROFILE IN USER CP.
 

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Thanks, I have done the profile. I do not get the paint colour dark blue as mine is Silver, they are definately the heater and AC controls that I have though.
The other thing/s I forgot to include is that you will have to inform your insurance company of the year change and the Motor Veh. Dept.

Two things have to work to get A/C or Heat to the rear. The first would be to see if the Rear Actuator Motor operates when it is commanded. This motor opens the duct work to allow air to the rear.

Remove the cover under the left side of the Instrument Panel, set the A/C controls to distribute to the rear and see that the Rear Actuator Motor operates. If it does not it must be replaced. If it does operate then the problem is at the rear of the console. Post back with results.
 

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ML 270 CDI 2002
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14 Posts
Discussion Starter · #7 ·
Firstly, in the UK the car insurance works a bit differently. The insurance companies use the veh. Reg. No. for most of the car manufacturing details. So no problem there. There is only One vehicle registration database in the UK and they have all vehicle information, they don't much care about model years, it is the year of registration that interests them.

Secondly, I do not think I need to check the actuators as you describe as I have been playing with the car for other things (rearcup holders do not work, no springs,front ashtray was stuck in) so I have had the centre console out. I can verify that pressing the 'rear off' button on the main heater control turns off the blower to the rear, and the flap in the rear duct (just under the ashtray) works, it closes when the engine is off and opens when the engine starts. I am prone to thinking that this is a control issue as the light on the rear 'auto' button does not come on, also the other two controls, Fan and air up or down do nothing. The flap does not close from the rear control, if it should. Thanks for your help so far.

Clive.
 

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'07 ML350, '05 ML350SE, '04 ML350, '01 ML55, '05 SLK350, '04 SLK200, '76 280SL
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You have me confused.

In your first post you wrote : The current problem is that the AC control in the back does nothing. I have tried turning off and on aotu from the front, I have also tried enabling and disabling the rear ac from the front. All of this still leaves the rear control doing nothing.

The above tells me that you are unable to operate the rear seat air flows from the main controls or the rear controls. True or false?

In your latest post you wrote : I can verify that pressing the 'rear off' button on the main heater control turns off the blower to the rear, and the flap in the rear duct (just under the ashtray) works, it closes when the engine is off and opens when the engine starts.

So do the front main controls operate the rear air flow or not?

Seems to me there is nothing wrong with your front main controls and your rear control panel is faulty.

Maybe you want to explain the problem with more clarity ... one scenario at a time.
 

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2006 ML500 2002 ML320
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Firstly, in the UK the car insurance works a bit differently. The insurance companies use the veh. Reg. No. for most of the car manufacturing details. So no problem there. There is only One vehicle registration database in the UK and they have all vehicle information, they don't much care about model years, it is the year of registration that interests them.

Secondly, I do not think I need to check the actuators as you describe as I have been playing with the car for other things (rearcup holders do not work, no springs,front ashtray was stuck in) so I have had the centre console out. I can verify that pressing the 'rear off' button on the main heater control turns off the blower to the rear, and the flap in the rear duct (just under the ashtray) works, it closes when the engine is off and opens when the engine starts. I am prone to thinking that this is a control issue as the light on the rear 'auto' button does not come on, also the other two controls, Fan and air up or down do nothing. The flap does not close from the rear control, if it should. Thanks for your help so far.

Clive.
You can do whatever you like, but think about this; if the truck is totaled or stolen you will be paid for a 2001 and not a 2002.
 

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Discussion Starter · #10 ·
RJV,
Sorry for any confusion. I have tried to get the rear control for AC auto to work with the front control on both auto and manual, hence turning the front on and off.

The front control for cutting off the air to the rear works as it should.

The rear AC button does nothing.

The rear fan switch does not control airflow.

The rear air direction switch does nothing.

I could believe that the rear panel was faulty but for the fact that the window switches are operating as they should.

Should the center switch be faulty then I will replace it. Knowing nothing about the vehicle operation yet I was thinking that it may have some wierd operational over-ride that I was not aware of.

What does the rear fan switch do?, does it operate another fan, extra to the main one, or does it partly close the flap? Thanks for your patience.
 

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RJV,
Sorry for any confusion. I have tried to get the rear control for AC auto to work with the front control on both auto and manual, hence turning the front on and off.

The front control for cutting off the air to the rear works as it should.

The rear AC button does nothing.

The rear fan switch does not control airflow.

The rear air direction switch does nothing.

I could believe that the rear panel was faulty but for the fact that the window switches are operating as they should.

Should the center switch be faulty then I will replace it. Knowing nothing about the vehicle operation yet I was thinking that it may have some wierd operational over-ride that I was not aware of.

What does the rear fan switch do?, does it operate another fan, extra to the main one, or does it partly close the flap? Thanks for your patience.
Rob, I don't know if I am following you correctly, but on the 2002+ models there is actually a blower motor in the rear.
 

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'07 ML350, '05 ML350SE, '04 ML350, '01 ML55, '05 SLK350, '04 SLK200, '76 280SL
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On my 2005 ML350 this is what I observed just now when I tried it :

1. When I press the rear "Off" switch on the main front controls on the bottom half of the centre insert of the vent selection control (third control on the right) this totally disables the ventilation controls at the back of the centre console. In the rear, the central red "Auto" LED extinguishes (if it was on) and the blower speed (left half) and air direction (right half) controls do not function and their respective red LEDs also extinguish (if they were on). Think of this as a "kiddies lock" .... the driver has used the main front panel to disable all the controls in the rear seat. Accordingly, no blower can can be heard in the rear and no air comes out of the rear face level vents or under seat vents.

2. When I then again press the rear "Off switch on the main front controls this enables the rear ventilation controls. In the rear the central red "Auto" LED illuminates and I can hear an actuator opening a flap at the rear and the rear blower fires up. Through trial and error, I have determined that this "Auto" setting is the same as having the rear blower on speed 2 out of 5 and the vent selection on 3 out of 5 (supposedly equally split between face level and under seat, but I can barely detect any air coming out at face level).

3. Following on from (2) above), as soon as I press either the rear blower speed or vent controls the central "Auto" LED extinguishes and then both the blower speed and vent controls become active (i.e. a Manual mode) and this is evidenced by one of the 5 red LED segments on each side illuminating. In this Manual mode the rear blower speed can be manually selected from 5 speeds (and the corresponding red LED segment will illuminate). Likewise, in this Manual mode the preferred vent source can be selected from 5 settings (and again the corresponding red LED segment will illuminate). In my car the bottom 3 settings pretty much direct all of the air out of the under seat vents, the fourth setting provides a mix of floor and face, and the fifth (top) setting seems to close the floor vent entirely and all air comes out at face level.

You have a rear blower and a rear flap actuator. You say that both of them work - when you press the rear "Off" switch on the main front controls the rear blower stops, and when you turn your engine off you can hear the rear flap actuator close (ergo, it must have opened earlier because the rear "Off" switch on the main front controls was switched to "On").

Given all of the above, I suspect that your rear control panel is faulty and it has failed in the "Auto" state .... as if the blower was set to speed 2 and the vent is setting 3.

There is still a chance of a discontinuity in the wiring between the front controls and rear control panel. The fact that your rear window switches work is not relevant - they are separate mechanisms with separate (dedicated) wiring and only share the same plastic mounting panel ..... even though they share the same multi-pin connector on the rear.
 
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