Also I wouldn't attempt to "by pass" the pressure switch to see if the compressor comes on without being absolutely sure there is refrigerant/lubricant in the system. check the low pressure side, on a running A/C system that should read between 20-40 psi depending on outside temperature.

 

I have a 1999 e-320 and the AC comes and goes intermitenly. In the summer it will be working fine and then all of a sudden it will turn off. In the winter the heat will be on and all of a sudden the AC will be on. If anyone has ideas please let me know

 

i used the ac diagnosis on benzworld and it said i have a bad evap temp sensor, here are values i got from the CC unit:
1-121
2-32
3-93
4-96
5-94
6-108
7-01


The AC is not blowing out cold air and no error codes, also if that is the case, what is the part number on that sensor?
Thanks in advance to any insight as to whats wrong

 

above the 3rd or 4th mark but never shut down completely.
it did it for a few months and now it seems to be OK now.
Look into the A/C blower regulator that you can do yourself if that is the problem...it is posted here on the forum.

 

#7 is the refrigerant pressure on the high side, this tells me the compressor is not coming on. Is your system filled with refrigerant?

 

You've got virtually no ref (#7), ext temp of 121f (#1), interior temp of 32F (#2) and coolant temp of 108f (#6).

I'm thinking the engine wasn't running when you pulled the data?

 

I have a 99 E300 Turbo diesel. The AC started acting strange - blows cool (not cold) air on the passenger side and blows hot air on the driver's side. The day it started doing this, it was working fine and then after sitting at a red light, it started acting up.

My husband is very handy with cars (has rebuilt some engines on older Mercedes that we have had), but he doesn't have a clue about what's going on with my AC.

Any help will be appreciated - we live in the Atlanta area and AC is a necessity during the summer months!

Thanks,
Mary

 

the onboard diagnostics.
http://www.eclassbenz.com/node/27
post the values1-8 and the error codes.
Most likely low r134a or a stuck duovalve.
Both pretty easy fixes in the short run and even if a small leak it should be easy to locate and repair.
ohlord
post those numbers after running the diagnostics per the instructions.

 

Sensor values:
1 - 78
2 - 87
3 - 67
4 - 53
5 - 134
6 - 166
7 - 09
8 - 100

When I tried to get the trouble codes, the only thing that came up was:
E FF

I went through the instructions several times and that was the only thing that would appear. Even trying to scroll through I'd still only get the E FF.
Also, I was a little off on my initial description of the problem. The passenger's side DOES work fine...it's only the driver's side that is blowing warm air.

Thanks for all your help!
Mary

 

duo valve a firm tap with the handle of a screw driver,just like a drum tap.
that may free it up.Does the a/c stay running or is it shutting down after a few minutes?#5 is the evap sensor and that value is a default temp to prevent freezing of the evaperator if the sensor goes bad.
$37 part at autohausaz.com and takes about an hour to replace.diy duo valve cleaning on benzworld.org w210 diy section. evap temp sensor there also or pm me.
ohlord
evap sensor working properly would be in the range of 34-40f for #5

 

10:1 it needs a does of refrigerant. My '99 had similar symptoms, and a 12oz can of Dupont r134 did the trick. Hubby can handle the job - plenty of how-to's on the internet. Just watch the pressure. It's fairly slow, taking about 1/2 hour to empty the can in my case.

He can also add an ounce of oil first if desired: same process.

Note that this does not mean you have a leak you need to fix. Studies have shown an average "normal" leakage of about 6% per year, and your car is 10 years old.

 

Obviously not cooling with 5 higher than 8, although #7 refrig doesnt appear low.

The tap on the duo-valve costs nothing.

I might try a quarter can of refrig if that doesnt help and then change the evap sensor.

 

3 and 4 are the evaporator temps. there is two one for passenger and driver side. not sure which is which but by looking at the temps you can tell one side is hotter than the other. I would also say you refrigerant is low.

 

left and right heater core temps not evaporator temp.5 is evaporator temp sensor and it is malfunctioning replace it and you will be cool city.
ohlord

 

sorry i was mistaken.

 

HEy everyone, I'm the new guy! Got my e320 last night. It has been in the family since it's birth and since my mother was going to sell it, I decided it would make a much more comfy daily driver than my current car.

Anyway, I am having issues... This post is about my A/C unit.First problem: left side is about 30 degrees warmer than right coming from the vents with both sides on low- Auto.

Second problem, there is a mechanical sound to the system that started about 3 weeks ago. It is sort of "surging" but also sounds like wind is leaking through a metal blade (sorry for the lack of a better way to explain it).

Anyway, I did the diagnostic check:
1 - 34
2 - 44
3 - 22
4 - 15
5 - 27
6 - 95
7 - 13
8 - 55

Now, these results are NOTHING like anyone elses that I have seen. When searching for error codes, I found none. Help me diagnose this mess!

As a side bar, the car is shaking pretty rough at idle. Any gas at all and it goes away. It only happens in drive, no problem in neutral. I will start a new thead about that .but wanted to see if they were correlated.

 

F difference.Both vents and heater cores are running too warm if set on low,and the difference added to the high evaporator sensor temp and the sound you have, indicate low r134a level.You need to have the leak located and repaired and the system charged.Nothing unique about your numbers.Just convert them to Fahrenheit
http://www.wbuf.noaa.gov/tempfc.htm
and enter them into the diagnostic software program.
ohlord

 

Ok, so engine mounts and AC leak.. Other than that, I am astonished by the ride of this car with 130k miles, even compared to the wife's 2 year old lexus.

How does one go about checking for an AC leak? I guess I should leave that to the pro's. Thanks again Oh Lord.

 

Today I just discovered that my 1999 E320 is leaking coolant. Yesterday afternoon, I was working on fixing the AC problem with my car (Hot air only, then cold passenger side and hot driver side, all to no avail, even after cleaning the duovalve). While sitting in my car, I noticed the coolant level message on my display, but I ignored it going to work, planning on dealing with it today. While parking my car at work yesterday, I saw a lot of liquid spilled while I was turning into the parking space. On the way home, I noticed the car temperature rising, and when I got home, the coolant system was steaming. This morning, I poured a little coolant in and drove to school to take my senior picture (only about 2 miles), and before I even made it home, the temp meter was almost hitting the red, so I stopped at a gas station and filled the coolant system with water, just so I could get home without it overheating. When I got home and parked in the driveway, the coolant system started emptying itself, leaking all the water out into my driveway.

So now I'm here, what do you guys think is the problem, and where should I look first? Any help is appreciated. Thanks in advance.

 

Wait until the engine is cool. Fill the system with water and idle the engine. You can start under the hood.

1 - Check the upper radiator hose and hoses to/from the tank. Check the radiator itself. It sounds like it's leaking pretty fast so it may be obvious.

2 - Put the car on jacks. Remove the sound proofing panels (if present) under the engine and examine the underside such as bottom of radiator, lower radiator hose and coolant lines to/from transmission.

Hope this helps some. Good luck.

 

Thanks for the reply, but the problem was solved. I took it to a mechanic, and discovered that the duovalve was not screwed together correctly. I was working on it yesterday, so I guess I didn't put the screws in straight, allowing for an opening in the duovalve, and for the coolant to come out. Luckily for me, my friends dad owned the autoshop I took it to, so the work was done for free (minus the $10 gas money). Thanks again.

 

It's all part of the learning experience.

BTW, be sure to get 50% antifreeze back in as soon as possible to protect radiator and system. You can get the MB product from www.autohausaz.com . I believe there is a approved Zerex equivalent. Do a search here or benzworld.

 

And recharge your AC first before going into heavier troubleshooting.

 

hot air on driver's side and cold air on passenger's side, couple with a hiss noise coming from the center vent might be LOW freon....
Good Luck

 

GO5.