xtrmerik

'97 E420

So my A/C is acting kinda strange and based on the info that I have found here and elsewhere, I can't seem to figure it out. When the car first turns on or runs while sitting still for a while there is a slightly warm humid air that gets blown out of all the vents. After about 15 seconds of driving, the air cools right off and blows nice and cold as long as I keep moving.

I ran the diagnostics for the a/c several times and this is what I've found so far. First there were some error codes, but I didn't know how old they might be, so I cleared them and despite driving for almost a week, no codes have reappeared. While driving if I record all the sensor values, the program says that my a/c is working just fine and all values are within acceptable range. When sitting still and the air blows warm, I get the following values:

36
40
30
28
51
86
29
83

The program then states the following:
Your evaporator temperature sensor appears to be malfunctioning. Usually a bad evaporator temperature sensor is indicated by code B1230. Your car does not indicate this code. However, a bad evaporator sensor does not always trigger the code. The sensor reports a temperature of 51 degrees. The outside air is only 40 degrees. It's impossible for your evaporator temperature to be that much warmer than the ambient air. When the evaporator temp sensor reports a value like this (and nothing else is out of spec), your A/C should run for 10 minutes after starting the car and then automatically switch off.

Ok, sounds like problem identified right? No, cause the a/c doesn't switch off after 10 minutes like this is saying. As long as I'm driving the sensor reports an acceptable value and acts like nothing is wrong. How is it that the sensor will report an "impossible" value while I'm sitting still, but then report correctly the entire time I'm actually driving? Someone please help, I want to kick something.

ohlord

then while sitting,run the test at 72/72,and post the values.Should shut down is the key word here,if the value reported is 123f converted from c,then it is out of range.faulty,So repost the standing 72/72 and the moving 72/72 values.First,I would do the r/r on the evap sensor.It is bad,autohausaz.com,instructions on diy on my post under a/c tips or on benzworld.org under same or in the diy section.By cold while moving do you mean that if set to low/low the car after 20 minutes is pushing 62f?
Post the values,relax,no thoughts of kicking,she (the benz)will feel the karma.
solutions abound,we need to find the correct one.

ohlord
"GOT CODES?"

xtrmerik

Thanks for your reply. I have actually read quite a few of your posts. It seems as if you are the main source of a/c knowledge on this forum. The values I posted were with it set at 72/72 at a stand still.

After taking all the time to type out my original post it got me thinking. I decided that it seemed as if airflow into the engine compartment was the key difference between the when it worked and didn't work. I poped the hood and decided to just look at everything while it ran. Turns out the main fan wasn't turning and that one of the blades had gotten itself jammed between the radiator and the shroud. After quickly killing the engine I freed the fan blade and all is well. I adjusted the radiator a little farther forward in an effort to prevent another seizure. Again thank you.

ohlord

What a find!See what I mean about a solution.And an odd one at that.Now is the evap sensor still showing the out of range or did your fix clear that up also?Lexrex is the guru,I am just a humble student of his and the school of hard knocks.Thanks for posting the fix,odd as it is ,someday someplace someone is going to need it.
ohlord
"GOT CODES?"