W210 Air Conditioning System Fault Codes - PeachParts Mercedes-Benz Forum

JimSmith · #1 11-17-2004, 07:38 PM

I have been having a persistent problem with the driver's side (left) dash vent, and the footwell vent, arbitrarily deciding to go from a set temperature to full heat. The only way to correct it is to set the automatic control to "Defrost" and endure a few minutes of intense heat, then turn it off and the system goes back to normal. For a while.

So, I dug up the diagnostic/code check procedure, printed it out and ran through it with the engine all warmed up and the air conditioning system in its mode of misbehaving. I got a code "Eb 1 459" which is "Series Interface (K2) connection to instrument cluster (A1)" and another one, which is not listed in the article, "E FF" and then pushing the Auto button again just makes them repeat.

Anyone know what these mean, and what I have to do to fix them? I am about to start my first air conditioning system repair ever and could use some advice or hints. Thanks, Jim

Gilly · #2 11-17-2004, 08:58 PM

Jim
Not familiar with the article or the codes being presented with these numbers
The "Serial Interface" code between the ACC and instrument cluster is present on most all of these. The interface isn't used until much later.
One problem I do know of that can cause this is the evap temp sensor. Maybe you can figure out how to monitor that and compare when it's operating fine and when it's in a failed state. Easy to replace.
Gilly

JimSmith · #3 11-17-2004, 09:51 PM

Gilly,

Here is the link to the page:

http://continentalimports.com/ser_ic40142.html

In Chart 3, kind of hard to read, it shows that the first code I get - the Eb1459 (spaced out a little differently on the display) - is the K2 to A1 connector. There is no reference to the E FF code.

I forgot to note the system behavior does not depend on having the A/C on. It is presently in the 40's Fahrenheit here, so I have the unit set to "economy" and get the same symptoms and the same responses - ok, then all hot on one side, turn the windshield defrost mode on, cook for a while, and then turn it off (push the button on the ACC console) and all is ok for a few minutes to hours. The exact same behavior when the compressor is on, or if the system is in "Auto" mode or I have manually set the fan speed and selected an air distribution setting.

That link suggests I can get the evaporator temperature reading by pressing a sequence of buttons. I will give that a try and see what, if any difference there is when it is ok and when it is acting up. Thanks, Jim

JimSmith · #4 11-17-2004, 09:55 PM

Gilly, I did not really understand what you meant by:

"The "Serial Interface" code between the ACC and instrument cluster is present on most all of these. The interface isn't used until much later."

Did you mean this code is not a sign of a fault and the serial interface is not on my car, on purpose? Thanks, Jim

Gilly · #5 11-18-2004, 04:27 AM

"on purpose" if you want to call it that. The easy thing for me to say is "ignore that code, they ALL have that code, it's not a problem". There is no interface, even thought he acc control unit could accept it, and faults itself for not having received it.
Gilly

JimSmith · #6 11-18-2004, 07:10 AM

Thanks, Gilly. I will take a shot at reading the evaporator temperature in both operating modes today. Jim

Gilly · #7 11-25-2004, 08:11 PM

What I'm not sure of (and maybe Steve is) is if the duovalve operation is similar to a mono water valve. If it is, you can get it in a failed state and find out if there is voltage to the control wires for the left side, you'd need to research which wires control this for the left or right.
If the scheme is the same as a mono valve, there should be NO voltage present, which represents valve ON, this would indicate a CONTROL problem, or if there IS voltage there, it represents valve CLOSED, which means the duovalve is the fault.
Gilly

benzfan · #8 11-25-2004, 08:25 PM

This is the exact problem I posted a question about the other day for my 96 C280 (no replies). Only on the 202, there is only a single readout for heater core temperature, as I do not have the dual zone head unit. I will be at the dealer in the morning to have it checked out. I can only think it's a duo-valve problem, but I'll let you know what they tell me.

benzfan · #9 11-26-2004, 10:40 AM

And the verdict is - duo-valve.

reelphun · #10 01-19-2005, 08:02 PM

Greetings,

I bought my 97 C280 sport 12 months ago. About four months after I purchased it the A/C output temp. stated to get warmer. I took it in to an A/C shop and they put a half a pound of refrigerent in it and it was cold again. They could not find any leaks. Six months after that the A/C started to get warmer again. I added a can of 134 refrigerent myself and it was ice cold again. Prior to that I noticed that when I accelerated the air volume comming from the vents would slow down. Last week It stopped blowing cold all together. I looks like the clutch is not engaging.

I went to the continental Imports site (http://continentalimports.com/ser_ic40142.html) about using the in dash A/C control to find fault codes. My A/C controler is slightly different than than the one in the article, it doesn't have the red/blue hot cold buttons on both sides. Is there a way to find the fault codes on my C280 A/C system.

Reelphun

Norman123 · #11 01-20-2005, 07:15 PM

Jim,

Thanks for the link to Continentalimports.com, great article. I tried it on my 1996 E320 and was able to read all the codes.

Thanks