W210Wagon

For you A/C experts. Help. 98 E320 wagon. The A/C will come on and blow cold for a few minutes until the compressor shuts off. Once it shuts off, it will never come back on unless you turn off the engine and restart the car. It will work for a few minutes, rinse, repeat.

Outside temperature in the mid 80's. Car warmed up. Thermostat set at 66 F. A/C codes immediately after starting:
1 32
2 33
3 22
4 25
5 60
6 77
7 17
8 61
9 00
10 2.7
11 4.2
12 4.1
20 6.0
21 06
22 00
23 00
24 13.3
40 71
41 34
42 72
43 152

I drove for about 10 minutes and there was no cold air. I adjusted the thermostat to "Lo". The fan increased in speed by itself but no cold air. A/C codes after driving:

1 31
2 31
3 35
4 35
5 66
6 89
7 07
8 36
9 01
10 4.5
11 4.1
12 3.0
20 0.0
21 05
22 00
23 00
24 13.1
40 71
41 34
42 72
43 152

Any advice/help would be greatly appreciated. Thanks in advance.

Plutoe

Very simple either you have a bad compressor or you have a leak and have low refrigerant level!!!----see an AC shop not your girlfrinds brother, unless he owns a shop!!

Have you done the fault codes???

W210Wagon

Thanks for the response Plutoe. I can believe that the refrigerant could be a little low, but there is more to the story. This problem actually started at the end of the season last year. I have been taking it to a qualified MB, Porsche, etc. shop. He had vacuumed and recharged the system last spring and it worked fine. When he checked it in the fall, he said it was only very slightly low on refrigerant. He said the leak was so slight it would be impossible to detect it with his sniffer. We did a visual check but we couldn't find any evidence of a leak anywhere. But, as soon as he tried to add any refrigerant, the low and high pressures instantly spiked really high. It really startled him. The compressor didn't shut off but the pressures were too high. He drained a little refrigerant back into his recycler to get the pressures under control. As soon as he did that, I was back to the same problem even though he said the refrigerant level was fine at that time. I admit that I don't understand all of this. Was there a fault in his proceedure?

Also, how do I get the fault codes?

Thanks.

W210Wagon

OK. I do have a fault code. Left side said Eb1, right side said 232. And then I got the FF.

Critter

To do the job properly the system must be evacuated then the proper amount of Freon is added back into the vacuumed system. By adding to the system without knowing how much is actually in the system damage will occur. You have pressure but is it Freon or just air? Hope this helps.
Does the fan start up when you select the AC and stop when the AC fails?

W210Wagon

Don't know. I'll check that.

Plutoe

Setting aside all the HS and polemics, the data and the faults are important to the diagnosis----In your case 1232 fault is important because it indicates that the refrigerant pressure sensor is faulty----to confirm that, typically you clear the fault and then running the car around do the fault test again----does 1232 return---if it does that could be the reason why it was reporting 7 bar when at first it was reporting 17. The other fact is that physics says that if you have 7 bar of pressure you must have about 82 degrees of temp---you had 36 and at 17 bar you should have 145----you had 61-----that is the reason for the warm air--your refrigerant pressure/temp was to low

What does all this mean, it means first that your so called qualified shop doesn't know anything(SFS) about auto AC---find another shop and if the fault returns change the sensor(which means that the system has to be emptied and refilled)

PS don't even think of doing this yourself!!

W210Wagon

Plutoe, I have been away so I didn't see your post. I'll clear the code and retest. I had to laugh at the "don't think of doing this yourself." I did the DIY thing on the evaporator a couple of years ago. That was a b*tch. How hard can the pressure sensor be?

W210Wagon

Finally got an opportunity to do a little testing on my wagon. I cleared the code. I didn't get to do a very long drive. Work interferred so I had to go right back. I did get to drive the car about 10 blocks. I don't know if that is enough to generate a code but no code showed. I watched setting 07 while I was driving. It started out around 17 but soon dropped to 15. When I was moving down the road at 35+ it would drop to 11-12. If I stopped at a light it would go up to 15. Once it finally got to 10, it continued to drop to 6. After that, it stayed at 6. It was 85 outside today, so it wasn't real hot. The funny thing is that the air coming out of the vents still seemed to be refridgerated, even when 07 was showing 6 bar.

Plutoe

Nice test----supports post 2---you are either low on refrigerant or have a bad compressor----next step put a set of gauges on and add some refrigerant.

W210Wagon

Thanks Plutoe. I'll do that.

W210Wagon

Aw, sh*t. The continuing saga. Vacuumed the system. Put in 1.2 pounds (I think) and fired it up. It was cooling but the pressure kept rising. Unlike the last time I worked on the A/C, this time the twin fans never came on. We quickly grabbed a water hose to cool the condenser. Pressures according to the gauges were a little weird. 280-300 on the high side and 40ish on the low side. And like always, after a few minutes the compressor would shut off and never come back on again. Shut off the car. Restart. Compressor would run for a couple of minutes, then quit. Rinse, repeat. Got to figure out why the fans wouldn't come on. More problems.

Plutoe

Remember that 14.7 psi = 1 bar, therefore 300 psi = 20.4 bar that's high assuming you want 15-17 bar.

Additionally the aux fans come on only when the engine coolant and or the refrigerant temp exceed a set temp, therefore what was the number for 8 when you were at 20.4 bar!!

W210Wagon

The water temp gauge on the dash was over 80. I didn't look at 8 on the climate control unit. Didn't think of it.

W210Wagon

And I just remembered one other clue. When the compressor was running and indicating 280+ on the high side pressure, I had the climate control diagnostic mode on 7 and it was indicating only 9 bar at the highest.

Plutoe

Oooooooooooooooooooooooooooooooooops

Plutoe

No specifice reason for Oooooooooooooooooooops, but remember what you said "And I just remembered"(like forgetting)-----therefore I said what I said but, I guess my response could have said OS, BS, HS and or Yo!!(like forgetting)

When are you going to stop playing around and take the car to a proper AC shop??

W210Wagon

Actually, I did go to one A/C shop that has a good reputation. I was explaining my problems and he looked at it. We went through starting the car and the compressor shutting off a couple of times. But he said he didn't really know anything about MB systems and didn't seem to be excited about tackleing the job. I was just hoping for a bolt from the blue on this forum. It has served me well in the past. And, for ecomonic reasons, I prefer to diy, if possible.

Plutoe

The AC shop you went to was very smart----know your limitations and don't screw with things you have no experience with!!

PS: If someone said-----you need a new compressor what are your home DIY alternatives to successfully complete the job!!

W210Wagon

I wouldn't cherish the job but I could do it. I have done it on other cars. I think compressors are relatively easy. I have access to a rack and a machine for evacuating and recharging the system. And plenty of tools to do the job. Parts should be readily available. But I have put a stethoscope on the compressor when it is running and it isn't making any growling/grinding sounds. And it is capable of making good pressure. I just keep thinking it has to be something electronic in nature due to the fact that it will cool when it is first started. It will cool for a while, then shut down and never come back on again until I shut off the car and restart it again.

W210Wagon

OK. New and a little confusing input from a mechanic. His 96(?) diesel was doing exactly the same thing as mine. He got into matching wave form monitors and other technical points I did not truly understand. Like bridging the N5 and N6 connectors to test. But the Reader's Digest version is that there is a safety interlock designed to protect everything on the front of the motor in the event the A/C compressor locks up. This interlock compares the speed of the motor with the speed of the compressor. It takes a couple of minutes to perform this diagnostic after start up. When they don't match it shuts off the compressor. Any ideas on how you would go about trouble shooting this? Or does this even sound plausible? Ironically, my lady friends 02 E320 did suffer a compressor lock up and it did damage quite a few components. Thanks.

Plutoe

What a line of HS---are you serious!!

First you have to understand how the MB compressor and system functions and then you have to learn how to take the actual value data and fault test---read the stickies and get a life and fire your mechanic bridging buddy as you will really screw the MB system up following his advice!!

W210Wagon

He is not the mechanic working on my car. Just a mechanic who happens to own a MB who said he had the same problem. I have no intention of bridging anything. It really didn't seem like a good idea to me. Especially the part about him not being able to turn his A/C off now. I just wanted to know if what he was talking about had any truth to it. Thanks.

HappyWagon

Hi W210Wagon,
I'd suggest visiting the following, where you can provide the full results of your climate control diagnostic, and receive an informed answer.

http://www.eclassbenz.com/2010/02/ho...-malfunctions/

Have you considered a leak detection dye?

Hope this helps.

Gehan

W210Wagon

Thanks Gehan, I'll check it out that link. I put in some of the leak detection freon a while back and haven't been able to discover any leaks, so far.