Hello everybody.

I have an E280 W211. I live in northern Italy (Milano).

Last summer air conditioning was not able to produce cold enough air. The problem was worse when car was stuck in heavy traffic. Air would chill a bit when on a highway.

Things already done:
1) last year I attempted to check and recharge refrigerant. Did not fix it.
2) a valve that is close to the charging and discharging plugs was changed. NO fix.
3) one A/C guy (while emptying refrigerant) told me there was a leak since he was not able to create a vacuum at desired level.
4) we attempted to throw water on the radiator with a pump and this would make air to come out a bit colder.

They wanted to keep the car for days (but since none of them would offer a backup car I ended not doing any repair). Summer was coming to an end so here we are, attempting a repair during spring.

Took the car to MB dealer/workshop and told them what was wrong and what had already been done. I got a backup car and they kept the car for about 10 days.

They said compressor was not compressing enough thus air was not cold enough. They replaced compressor (MA002 230 66 11/80), evaporator (MA211 835 00 47), valve, external temp sensor, etc.

They give me the car back and it still does not work. We tested on a relatively cold day, but air coming out was not cold enough. On their shop, they attached the computer and set it showing A/C data. Air temp out of evaporator was (according to computer) at 2°C - 35F.
Strange behavior observed: pressure on refrigerant was at max (30) or a little above (31), and temperature shown on dashboard would ramp up very fast (from 22°C-71F to 47°C-116F in about 3minutes). The guy from MB could not explain why that temp was that high, but according to him blown air was cold. I asked him what temp should it come out at and to measure it. He said he did not have a tool to measure it and did not know at what temp it should come out.

The temp shown in dashboard does not go up if the car is moving enough ... this makes me think of radiator not cooling enough.

Hypothesis/questions:

Q1: what temp should the air be when coming out from blowers , when A/C is set to max? both recycling and fresh air.
H1: could it be the cold/warm valve defective?
H2: could it be the A/C radiator ?

Thanks in advance for your help

Michelangelo

 

Has anyone had a careful look at the cooling stack (radiator/tranny cooler/oil cooler/AC condenser)? I've seen cases on other vehicles where birds have built a nest between coolers and effectively blocked air flow. Disassembly required for proper inspection.

 

not that I know ... I will ask MB to check that ... I have asked them to replace radiator and will take it in thursday, but that is my opinion and not being an expert, I do not feel confident it might solve the issue.

 

We should have stickies for HV/ AC troubleshooting.
It is pretty easy on those cars and I just replied to parallel topic with links and how to procedure.
https://mbworld.org/forums/e-class-w...tuck-cold.html
Good call on checking the radiators. I bought a car from TX one time and even it was detailed for sale, I found whole lower part of radiator (behind the bumper) pack-up with dead insects.

 

I brought the car back to dealer, asked them to replace the A/C radiator . Now A/C is blowing cold air. Probably too many miles made radiator to accumulate dirt inside and it was not able to cool efficiently.

I am mad since dealer probably replaced compressor and another thing (3.000 eur) for nothing. Replacing radiator was 800 eur and fixed it. And they did not want to do it because they were sorry I would spend more money for nothing.

Lesson learned: think before, do not trust dealer regarding A/C.

In fact, even other shops did not think of replacing radiator.

 

It's a sealed system - I'm trying to imagine a way that dirt or any crud could accumulate inside the radiator unless something shredded itself (like a compressor) and clogged up the works. Did they show you the old part that they replaced? Your story sure makes me lean towards the fins being clogged with debris (on the outside, not the inside). That could've been taken care of with a simple cleaning.

 

I did try to clean it on the outside but it did not help much. I tried cleaning it with high pressure water (the one we find in car cleaning stations).
They did not show me the old piece.
It definitely works better now.