210 chassis climate control problem - PeachParts Mercedes-Benz Forum

sokoloff · #1 02-06-2004, 08:49 PM

Can somebody please either tell me what the correct AC pressure should be or run the diagnostic on their properly functioning climate control and give me their read out? Item #7 is the refrigerant pressure in bars. Mine reads 3, but I don't know what it is supposed to be. My "Economy" light is always on. That would tend to indicate low refrigerant, but I have a service bulletin that indicates that the temperature sensor has been a problem and causes this to happen even if the refrigerant isn't low. So, if my pressure is within specs, I want to just change the temperature sensor. Also, can the temperature sensor be replaced without draining the system?

I've pulled the fault codes. They are as follows:
B1231 - ECT sensor
B1234 - Sun sensor
B1241 - refrigerant fill

The problem is that the service bulletin says to change the refrigerant temperature sensor whether the refrigerant is low or not. So my thought is that if I can change that sensor without having to drain the refrigerant, then why not just change it first, disconnect the battery cable to erase the fault codes and see if that fixes it? That is assuming that my refrigerant pressure is within spec which is what I don't know right now. I can't tell
you how inconvenient it is and how much I really hate to take my car in for service.

Thanks.

Len
'99 E300TD 58,500 miles

stevebfl · #2 02-06-2004, 09:11 PM

If I recall the pressure is of the high side. It should be 300psi or so when running and hot out. The value on the push button unit will be in bar, so one would divide by 14.2. Three bar would only be 45 psi, but if it isn't on (economy) and its cold out at all, 45psi could be OK.

What do you get on position #5 evaporator temp sensor. In the morning after everything has sat the first few actual values are temp sensors including 5 and they all should be the same temp if tested before the car runs.

sokoloff · #3 02-06-2004, 09:53 PM

Thanks for the reply Steve. Thanks also for your great info on your web page. Here are the numbers I got;

Outside temp sensor - 61
01 - 64
02 - 60
03 - 60
04 - 62
05 - 109
06 - 57
07 - 3 bar
08 - 60

These are all with the car not having run in a couple of days, so everything is cold and I would think ought to be the same. What's up with #5? Is that telling me that it's my temp sensor that could be the issue?

Len

stevebfl · #4 02-06-2004, 09:56 PM

Yup!

sokoloff · #5 02-06-2004, 11:11 PM

Now for the big question - can I just unscrew the old one and screw in the new one without draining the system?

Thanks for your help. It is much appreciated.

Len

stevebfl · #6 02-06-2004, 11:17 PM

The evaporator temp sensor doesn't go into the refrigeration system and it doesn't have to be discharged to bereplaced.

sokoloff · #7 02-06-2004, 11:34 PM

Beautiful - I think that ought to be my starting point then. I'm looking at part #210 830 00 72 called temperature sensor with a wholesale price of $25.50. Does that sound like it? There's another sensor there too that is just called a sensor, part #140 830 00 72 with a wholesale price of $52. This sensor doesn't need to be replaced correct? Both of them use the same sealing ring.

Thanks so much.

Len

RPM55 · #8 02-07-2004, 07:24 AM

The refrigerant temp sensor is located on the dryer and the system does have to be discharged before replacing the sensor. The evaporator temp sensor plugs into the left side of the evaporator housing. The left side underdash panel has to be removed to access the sensor.

stevebfl · #9 02-07-2004, 08:26 AM

I think the new number for the evap sensor is 210 830 07 72. Used to be 05 72

sokoloff · #10 02-07-2004, 10:16 AM

Thank you both for the replies. Now I am a little confused. I/we maybe talking about at least two different sensors here.

1. The service bulletin I have says to replace the "refrigerant temperature sensor (B12/1)" in all cases whether the refrigerant charge is full or not.

2. The bad diagnostic readout I'm getting, i.e. #5 reading 109, is called the "evaporator temperature sensor."

Are these both the same sensor or is the one in #1 on the dryer and #2 the one on the evaporator housing under the dash? If we are in fact talking about two sensors, what is your stance on replacing the one on the dryer based on the service bulletin?

Steve - you were referring all along to the evaporator temperature sensor when you said it didn't go into the refrigeration system. I, however, was looking at the sensor on the dryer.

Thanks for bearing with me on this guys. I really appreciate it.

Len

stevebfl · #11 02-07-2004, 02:57 PM

I have read that bulletin a bunch, and I wouldn't want you not to replace it if that is your desire. I was only respoding to your symptoms and the real problem you obviously have.

I can't say much about the pressure in the system without putting a gauge on it and if you wish to replace it you will have to drain the system and recharge afterwards.

sokoloff · #12 02-07-2004, 03:17 PM

Okay, thanks Steve. So the sensor you were talking about and the one I was talking about based on the service bulletin are two different sensors. I'll just try changing the evaporator temperature sensor and see what happens. That one sounds like an easy screw in, screw out job.

Len

stevebfl · #13 02-07-2004, 04:06 PM

You have a problem based upon the actual value. You will see that when you replace it. The evap temp sensor will keep the compressor off, but I'm not sure if it will light the economy button. I actually don't think it will.

You definitely need the evap temp sensor and it is not too expensive. You do need to evaluate the pressure switch issue though as it could turn on the economy position and if so will keep the AC off as the bulletin explains.

sokoloff · #14 02-18-2004, 04:35 PM

Got my new evaporator temperature sensor and am ready to put it in. When you say the left side under dash panel has to come off, are you talking about the black plastic horizontal piece under the instrument cluster, the vertical carpet covered piece on the left side of the center console or both? I have both of them loosened up a bit, but can't get eitehr of them out yet. Any secrets or hidden fasteners? This is my first attempt at the dash panels on this car and I don't want to force something and break it.

Thanks.

Len

stevebfl · #15 02-18-2004, 05:48 PM

The panel that needs removing is under the dash. There probably is some technique in the archives or you can see the actual work instructions in the MB online info site www.startekinfo.com. It will cost you 25 to get in but everyone should spend a couple hours there if one wants to work on these cars that have no print service manuals.