know this is an old topic, but i can't seem to find anywhere what the acceptable range is for values off the a/c diagnostics screen on a 1999 clk320

i followed the directions at http://www.continentalimports.com/ser_ic40142.html and got the following error codes
eb1 226 ... in-car temperature sensor
eb1 227 ... outside temperature indicator temp sensor
eb1 241 ... refrigerant fill
eb1 419 ... electromagnetic clutch
eb1 422 ... series interface connection to instrument cluster


also received these values from the a/c pushbutton control
1 in-car temp sensor......................... -40 (that's negative 40!)
2 outside temp indicator temp sensor......... 68
3 heater core temp sensor left............... 73
4 heater core temp sensor right.............. 74
5 evap temp sensor........................... 102
6 ect sensor................................. 70
7 refrigerant pressure in bar................ 5
8 refrigerant temp sensor.................... 69
10 blower control voltage.................... 1.2
24 battery voltage........................... 12.2
40 software status........................... 6
41 hardware status........................... 3
42 ?......................................... 168
43 ?......................................... 8

Just wondering why the in-car temp sensor is registering a negative value!?!
There are plenty of error codes but i'm guessing the best place to start is to replace the evap temp sensor ($42 part)?

a/c's been out for 2 years now so it'll really be something to have it working again! (will also end the 2 years of complaining from my wife for making this car purchase)
had an a/c recharge at a local shop 2 years ago, the ec light came and stayed on thereafter and a/c stopped working ever since.

Thanks all!

Spend the 1K and get a new controll unit. If that what a reputable shop has deemed bad. It is kinda common.

Will b1422 cause b1226? I'm not sure which way the communication goes, but both of them are supposed to know the outside temperature.

Found this tool while browing on benzworld.
http://www.eclassbenz.com/acdiag

it's pretty cool, just enter in your error codes and sensor values and it gives an instant assessment and workarounds if there are any.

My response was as follows:

- Your 'EC' light must be off for the A/C to work. If the light will not shut off when you press the 'EC' button, this usually means one of three things: (1) You're low on refrigerant; (2) You have a defective refrigerant pressure sensor (usually caused by excess moisture in the system); or (3) You have a defective refrigerant temperature sensor.

- You have an error code for low refrigerant (Error code B1241).

- You should have the defective sensors replaced. But in the interrim, follow these instructions to override the sensor. (Your A/C compressor has its own pressure switch, so overriding the 'EC' light will not compromise this safeguard.) Switch the ignition on (position 2). Set the left temperature to 'HI' and the right temperature to 'LO'. Switch the ignition off. While holding the 'REST' button, switch the ignition on (position 2). On the left side, 'P1' will flash and on the right side, a code will be displayed. Press the 'EC' button twice so that the left side flashes 'P2'. Using the right side red temperature increase button, add 16 to the value. Press the 'EC button again to store the updated code. Turn the ignition off.

- Code B1226 Explanation: This sensor measures the temperature inside your car. It is reporting an implausible temperature. The sensor is located behind the small vent near your cabin light switches in front of the sunroof.

- Code B1227 Explanation: This sensor measures the temperature outside your car. It is reporting an implausible temperature.

- Code B1241 Explanation: You're low on refrigerant! Get your A/C recharged and this should go away. This code disables your A/C. You may be able to bypass this block if it's triggered by a defective sensor.

The trick to add 16 to the sensor measurement was particularly interesting. There were other posts in this forum that referred to this but didn't provide a link to the details. I made the change yesterday and will let you know how it fares after I test drive the car this weekend.

Car would crank but wouldn't start intermittently. Beginning yesterday, the car (mind you a 1999 clk 320 with only 75k miles) engine would cut out whilst i was driving. First time, the car died in a busy parking lot and the second time, in the middle of the street! I had to get out and push it out of the way of traffic.

Not sure if the item below was the cause, but it sure is suspicious as it was the only change made recently...

"- You should have the defective sensors replaced. But in the interrim, follow these instructions to override the sensor. (Your A/C compressor has its own pressure switch, so overriding the 'EC' light will not compromise this safeguard.) Switch the ignition on (position 2). Set the left temperature to 'HI' and the right temperature to 'LO'. Switch the ignition off. While holding the 'REST' button, switch the ignition on (position 2). On the left side, 'P1' will flash and on the right side, a code will be displayed. Press the 'EC' button twice so that the left side flashes 'P2'. Using the right side red temperature increase button, add 16 to the value. Press the 'EC button again to store the updated code. Turn the ignition off. "

Code fixed my a/c fine, but if it comes at the risk of cutting out my engine, then maybe i'll just stick with the rolled down windows! Anyone have any thoughts on this, could my problem be related, or do I also have one of the fuel or OVP relays that they talk about elsewhere in the forum.

I rolled back the change and will see how it goes today, but it sure sucks to have to push your mercedes down the street!!!

The AC is probably not at fault for your engine quitting. I'm not sure if this applies to your car, but the notes for the 210 say to set the version code P2 to ignore the refridgerant level in all cases. This almost certainly doesn't apply to you (as adding 16 caused the AC to run), but if 16 were previousely added and you added 16 again, you would be turning the 16's bit off and the 32's bit on, which is not what you want.

I'm fairly sure that you have some variant of the OVP or K40 module. It's much more likely to be at fault than anything in the AC. But also consider the crank position sensor as a likely suspect.

Thanks Matt L. I did subtract 16 from the number I had added earlier to reverse the change I had once made. A/C still works but the engine still cuts out. Died twice today and had to push the car twice today.

I'll do some searches for the items you mentioned... Hopefully, none of them are ridiculously pricey and are DIY items... This must be the 20th part i've replaced on this car in the past 3 years. What a lemon! (and what a pissed off wife I have I might add for buying this car in the first place)

Found this in another post:

"I was on my way to work this morning after not having the car cut out on me for a day, but unfortunately, on the 15km stretch from my house to my work, my car died on my three times.

... MB road side assistance ... passed me onto Danny who was the mechanic in charge at that time, also no wait time.

I told Danny what my problem was, that the car dies on me without warning, at anytime and refuses to restart for a few minutes, Danny said that this looks like a fuel issue, and that it is very possible that the fuel pump relay is overheating, or that one of the temp sensors is giving an incorrect reading which causes the fuel to shut off to prevent damage to the car."

I know that I definitely have a problem with a temp sensor as its what's causing my a/c faults. (although its an evap temp sensor which I wouldn't think would be related) I wonder if based on this post, it's causing fuel problems as well.

Did I mention that the car doesn't start up right away. I have a wait a while for things to cool down. Otherwise, the engine just cranks and cranks but never catches. Thanks all.