Help With '99 C280 A/C Diagnostic Codes - PeachParts Mercedes-Benz Forum

mbdoc · #1 04-28-2009, 04:45 PM

Not on WIS, guess MB deems job too simple.

Removal of the drivers under dash panel is required. Located above gas pedal area.

D3RDEYE · #2 04-30-2009, 01:08 AM

Thanks, M.B.DOC. I also had gone to my local library and checked out the ALLDATA info for this item. The ALLDATA site has a photo of the underside of the driver's side dashboard, but unfortunately, it was not a very sharply focused picture. The ALLDATA photo or site does not have any written word direction for this repair. You have just the photo to guide you. However, once you get your bearing by knowing what you are looking for and where to look, the slightly blurry and not very sharp photo makes a bit more sense. Nonetheless, I now know it is definitely a repair I can handle.

I am going to wait until I get the sensor. I actually found it at a couple of online stores for $36 and $39 plus shipping. I will post a feedback once I have it installed.

D3RDEYE · #3 05-03-2009, 10:27 PM

M.B.DOC., while I am here, what's your opinion on synthetic R134a? Can it be safely mixed with regular R134a?

D3RDEYE · #4 05-08-2009, 04:56 PM

I have installed a new evap temp sensor and am now getting the following diagnostic readings:

01 = 98F
02 = 81F
03 = 91F
05 = 91F
06 = 177
07 = 03*.0
08 = 84F
09 = 50F
10 = 495
20 = 00
21 = 060
22 = 000
23 = 000
24 = 13.8
40 = 03
41 = 03
42 = 26
43 = 6-C
50 = 89F
51 = 60F
52 = 50
54 = OFF

From the above readings, it appears that my evap temp sensor reading has improved from what it was before (122), but it still seems to be running high. Please correct me if am wrong, but I believe I read somewhere on this forum that it should be running much lower.

Also, it appears that my a/c compressor is not kicking on because am still not getting cold air from my a/c. The R134a pressure is a little higher than it was before but that may be due to the 5oz or so I was able to pump into the system before the pressure indicator climbed close to the yellow line on my pressure indicator gauge.

My question then is this; why is the compressor not kicking on and what can I do to correct that and get an ON reading from #54 above? Am I getting a wrong R134a pressure (content) reading due to a faulty pressure gauge? And, shouldn't the refrigerant pressure bar be higher than 03*.0 if the canister is really full? M.B.DOC or any other member out there that can , please help!