MLGus

Dear all

i need some advice please.

I have got a ML350 W163 and the air con is doing funny things. the hot air is fine, however the cold or air con doesnt work properly. when i set the commands to cold it doestnt work, however if i set the command to cold and i switch off the engine and switch on again the air con works.

i took it to the mercedes dealer and they put another AAC to see if it works which did work, however they said it is 900€ for a new one so the gave me the option to find a second hand.

i have bought two second hand AAC ( part number A163 820 42 89 ) by now. the first one didnt work so i got my money back. the second one works but it is set the other way around, when i set the command to cold it gives me hot air and when i set it to hot it gives me cold air also the command to direct the air flow it is the other way, down for windscreen, up to the feet.

Can this be fix ? maybe it needs to be re-program to my car, is there anyway to fix my old AAC and the problem so i dont have to spend that much money on a new AAC ?

i am a bit confuse, perhaps the part number is not the right one ?

if you guys can please help that would be appreciated.

Thank you

Aar Sto

What's wrong with the old one? If it has a damaged circuit path then it can be repaired by soldering in jumpers, but you'll need to fix what caused that damage first.
http://www.benzworld.org/forums/w163...trouble-4.html

MLGus

I opened the AAC module and didnt see any visual damage or burnt circuit what means the module needs to be re-loaded with data or perhaps a chip or capacitor is gone.. i dont know, but no visual damage.

The AAC climate control i got works but with the controls the other way around as i described earlier.

it is a bit tricky, dont know if the module can be re-program with different data to fit my car or if i bought the wrong part which i think is a163 820 4289

Thanks anyway.

Aar Sto

Are you sure you're looking at the AAC and not just an OK module? If it works the other way around then it is useless and there is no repairing that. I would toggle and thermostat the air condition and move on to something more important.

Maj. Dundee

Please UPDATE YOUR PROFILE in USER CP to include the year of the ML and where you live.

MLGus

Hi Maj

I have updated the details you required, i think i have done it properly otherwise please let me know.

Thank you

Maj. Dundee

Great.

Maj. Dundee

What is your full vin#?

MLGus

Hope this helps

Thank you

Maj. Dundee

This is the part number that is required. There are three for sale on ebay and they are in Eu.

http://www.ebay.com/sch/i.html?_odkw...05589&_sacat=0

MLGus

Thank you

I'll order one and let you know

MLGus

Hello All

just a quick update on the case.

I ordered the 1638205589 from germany and the air con didnt start up so i fix the previous one which it works but with the controls the other way around as i described previously.

i took the car to the nearest merc. dealer and they did their magic, To code the control unit. All working now and with the controls doing what they are supposed to do.

Thank you all for your help

Maj. Dundee

Great news.

markloch

AC has always been flaky since I purchases the 03 ML500 three years ago. When it does blow cold, it's cool, but nothing near as frigid as the AC in my 02 CLK55 nor my previous 98 E430 that the ML replaced. In those two cars, AC kicks in almost immediately; in the ML it's hit and miss, but typically it takes a few minutes, sometimes more, to kick in (there are times when it can take 10-15 minutes). Sometimes it kicks in quickly though never immediately as the other cars will, unless the engine had been turned off recently and the AC had been running prior.

Insofar as I have been able to check - typically I'm driving when the AC kicks in - it seems that the AC kicks in as soon as the aux fax starts spinning. Maybe it was for some other model, but I thought I'd read that this was expected: the aux fan had to be running before the AC would kick in. Is that corrrect?

If so, what confuses me here is if the fan wont spin until the coolant temp reached minimum (105C) or the refrigerant pressure reached some minimum (16bar), how can the pressure rise to 16bar (to start the fan) if the compressor wont kick in unless the fan is spinning? Or do I have this wrong? If I'm right, might it be that the pressure sensor is screwy, passing incorrect data to the AAM?

Anyway, the car was at my mechanic for other work, and I asked him drain and refill refrigerant as a baseline. He said it was low, but didn't elaborate. He put dye in it so we can check for leaks (question: will a cheap LCD UV light readily available on Amazon suffice?). I thought behavior was improved - it seems it kicked in sooner - but just yesterday it took about ten minutes of driving to kick in.

Before I head to an AC specialist, I'm wondering if there are some additional steps I can follow to help isolate where the problem lies. I have access to gauges, multimeter, plenty of tools ...

Any help appreciated!

Maj. Dundee

Post your full vin#. The correct part number depends on your vin#.