S class AC problems

[1994C220]

I have a terrible screeching noise that starts as soon as I turn on the climate control system. The noise stops as soon as I turn it off, or if I switch to EC mode. It sounds like it is coming from the fan belt...being a complete novice even in auto repair, I was wondering if someone could help me by telling me what is the cause of this noise, and how serious it is.....I know that my blower regulator is out(the AC system only blows on low), and I wanted to see if there is more that is out besides the blower regulator...such as the evaporator, the compressor and whatever else might be out...I have tried to get the DTC codes using the K6RF's website...but the best I could do were the sensor readings...I followed the directions for the DTC codes on the page...but it kept giving me the sensor reading only...Someone....PLEASE HELP!

Here are the sensor readings:

1 - 76
2 - 93
3 - 7
4 - 19
5 - 14
7 - 3
8 - 40
9 - 30
16 - 0

[1994C220]

Ok...I finally got the diagnostic codes off the climate control...I had the following error:

EO91

Could someone point me in the right direction on what to check from here? I have checked the code on the website, and found its an open or grounded circuit for the compressor...how can i check/correct it?


Thanks in advance for your help.

this is a great website:

http://pages.prodigy.net/jforgione/MB_S500.html

Should answer your questions...
Good luck,
CK

[bobterry99]

Hundreds of people on this board know more about this than me. But I think the screeching may be your A/C compressor clutch slipping or the belt slipping over the compressor pulley. Though it is my understanding that a motion detector on the compressor will detect these problems and cause the compressor clutch to disengage. I suggest watching the compressor clutch when you hear the screech to see what may be happening.

[1994C220]

Thanks for the help...I will check it out...could the compressor also be freezing up? The blower regulator is out, and I am not sure abotu the evaporator, but that could be out to...all I know is that this could be a very expensive fix...but I got this car really cheap, and for now, Im not to concerned about the AC since its 40 degrees outside right now. But I will want to get these things fixed before May or June


Thanks.

[jbaj007]

Since there is no screech in "O" or "EC", I'd guess siezed compressor. Try turning it by hand. If it turns, look at the clutch; if it doesn't turn...compressor.

[JimF]

number '7' and it reads low, 3. I would think that it should be higher even with A/C at 'rest'.

If it's not seized, it probably is low in R134 and won't start. The belt could be slipping.

Just other alternatives.

[1994C220]

I havent had much time to look into my climate control problems because I just moved into new home...although I did wish I had at least fixed the blower regulator this morning...IT was cold! The heat that trickled out of the vents was just teasing me....anyway...Im ordering the blower regulator today...and I have a post from this board from someone that has done this...seems simple enough...Just have to find some way to get up underneath the car...Can someone tell me where to look for the part? In the post it says its right about where the wiper blades are, but underneath the engine...

I will update on the compressor/pulley/clutch problem once I get this regulator in. Im hoping its not the compressor.

Thanks,
Carlos

[jayhawk]

I replaced the regulator in my 140 recently. Very easy job. Make sure you disconnect the battery first. My blower regulator was on top of the blower fan which is under a black panel on top of and behind the engine just in front of the wipers. There are several (6 to 8) large phillips screws which need to come out around the panel (do not mess with the small hex screws on top of the panel). A few of the screws do not pop right out at you - so look around the entire panel carefully and you will find them. Then lift the panel up just enough to access the fan, which is under the cabin air filter (remove), on the passenger side of the panel. The new regulator I received from fastlane (check around - fastlanes was less than half my dealer's price) came with a special cloth to remove the old heat sink and the new regulator came with heat sink on it. Install the new part by setting it on the fan and twisting it into place to spread the heat sink, fasten the two screws which hold it down and plug in the wires. Be careful not to drop the screws into the fan. Put it all back togather, hook up the battery, reset the radio and it took me about fifteen to twenty minutes to do.