Hi there,

I recently bought a second-hand 2001 s320, it was very clean really cheap (US$3000) but it came with some problems. I can summarise them in 4 points:

1) The AC/off button is always on (the red LED light does not turn off), which means the AC does not turn on. I thought there was no gas in it. I went to an AC guy and he filled it with air first, and the light stayed on. I said the AC won't turn on unless he filled gas in it but he told me the car doesn't understand if we filled it with gas or air. There was pressure in it and the "AC off" light was still on. He told me to take my car to an electrician first, to check if there was any fault with the controls or the air compressor.

2) I replaced the old flat battery with a brand-new one. The new one goes flat if I don't use the car for 2-3 days. I manually checked all the lights in and out but couldn't find anything. How can I understand the problem?

3) The front and rear suspensions go lower overnight. Sometimes only fronts go low. Sometimes both stay ok. Is it the air suspension failure (like leaking air) or the air compressor that doesn't work properly? Sometimes the fronts go low while I am driving and a "STOP, THE CAR IS TOO LOW" warning appears on the screen. How can I understand the reason?

4) The odometer readings on the government website (Service NSW) is 89.000 last June, it is 85.000 last year and 81.000 two years ago. But the odometer shows ---------- at the moment. We couldn't read. The previous owner said something like "We had to change the key and the key module" and that could be the reason of showing ------------. What should I do if the new key module is more than 89.000 and the computer shows more than 89.000? Is there a way to calibrate the reading? Like on what other modules does the car register the odometer?

Thank you very much.

 

The AC system has to be reset using the Mercedes computer diagnostic system to work. Battery going dead can be from a number of issues, most common is the navigation disc in the factory command unit. But there are a number of other possibilities for battery drain, from the alarm siren to any other part not going to sleep when the car is off. What I like to do is buy a remote control battery disconnect , so I just click the key fob and it will disconnect all battery drain

they sell them on eBay for about 25 bucks.
The air dropping is most likely a strut with the air leak, but it could also be a leaking line or leaking valve block. An easy test for the front struts is to spray the top of the struts with soapy, watered and look for bubbles

and Yes, the odometer displaying all dashes is a result of switching those other parts. There is no way to get it to display the mileage.

 

@tusabes
Thank you very much for your response.
AC Problem: So, do you think it is a software problem that will be fixed when reset? Can an auto electrician also reset the system or do I have to take it to an official Mercedes service? I probably will spend more money than the car itself if I go to a Mercedes service. My AC guy told me the car wouldn't understand if there's gas or pressured air in the refrigerator is that right? Because he tried to turn on AC while there's pressured air in the system.

Battery: Thanks for the idea about the remote control battery disconnect, it is absolutely genius. Let's say the electrician found out it is because of the navigation disc. Is it possible to disconnect it so it doesn't drain the battery?

Air suspensions: So you don't think it is because of the compressor because it pumps well and then it goes low by itself right? Do you recommend me to replace them with coil springs? Is there too much difference between Chinese ones and Arnott's coil springs?

Odometer: We need to read the odometer once a year and register the car to the state authority. Is there a way to read it?

 

I provided you the answers already, why do you keep asking more questions? I told you you need the Mercedes factory computer to reset the system, many independent garages have the Mercedes factory diagnostic computer not just a Mercedes dealership.

 

With all due respect sir, how am I supposed to know that many electricians have that? Thanks anyway.

 

The AC/off button is always on (the red LED light does not turn off), which means the AC does not turn on. I thought there was no gas in it. I went to an AC guy and he filled it with air first, and the light stayed on. I said the AC won't turn on unless he filled gas in it but he told me the car doesn't understand if we filled it with gas or air. There was pressure in it and the "AC off" light was still on. He told me to take my car to an electrician first, to check if there was any fault with the controls or the air compressor.

Answer: (reset the ac computer this hapents to me)

 

I replaced the old flat battery with a brand-new one. The new one goes flat if I don't use the car for 2-3 days. I manually checked all the lights in and out but couldn't find anything. How can I understand the problem?

how much amps is drown? if more than 1,amp then it is Sam issue
remove one by one Sam connection you can find it, which Sam doing this.. (pull left side Sam remove all the connection and check with multimeter need to be 0.04ma )
do you know how to check draw with multimeter? If you dono u can ask me

this all happen to me man.. really i learn more about w220 s320...
if you have any dout anytime u can contact me