agla2008

2008 E350 4Matic…New Owner…Lots of questions…here goes
When you start the car after it sits overnight or after it sits for a few hours the a/c automatically comes on. The a/ c switch has not been activated nor is the red light on in the switch and The system is not in Auto. The a/c stays on for about 5 minutes then goes off. There are lots of days when we don't want a/c so its a bit annoying. Is this normal or?
I also never see water dripping from under the car when the a/c is running for extended periods of time…normal or? We do get some stinky a/c smells so wondering if the drain tubes might be blocked. Cabin air filter changed. Watched a video on youtube that showed how to remove the tube under the dash and then spray a disinfectant into the system to kill any bacteria, mold etc…a good idea or ?

chassis

Welcome! Please post a photo of the E350. Smelly A/C is common. No fix available, just a treatment as you mentioned. For the A/C control questions, try posting in the W212 section where owners will see it and can provide suggestions.

agla2008

Thanks…will post a better photo shortly. Curious…why W212…thought my 2008 was a W211 which is where I thought I posted…

MJ50

moved to W211 forum...

MariusNL

I have the same ''problem''. When starting the car, the compressor runs for about 5 minutes (I know this because it makes a bit of noise) and then shuts off. Even though the button is off. Very annoying because when it shuts off after 5 minutes, the windows start fogging up until the evaporator core has dried up again. Especially in the current colder days it's annoying. I'm going to disconnect the AC pressure sensor for the winter months just to prevent it from coming on.

agla2008

Have you had the MB dealer or other service facility look at it to see if theres an problem or is that the way it was designed? Where is the AC pressure sensor located…could it be that its faulty or?

E55Greasemonkey

It's designed to always come on at startup to dry the air trapped inside the car and prevent the windshield from fogging.

agla2008

Thanks…saves a trip to the dealer$$$…Living in he Desert…I wish we had humid air to dry up!

Red Ryder

Congrats on the car! If things go right I should be finally getting mine next week.

From what I've read, A/C smelling musty/moldy is common, as stated above. My ATS has the same issue, I just turn off A/C and let it blow heat for the last 5 -10 minutes of my drive to try things out instead of shutting off the car with A/C still running. Seems to help on that car, don't know if that will work on a W211.

MariusNL

No the sensor is new. I'm disconnecting it so the system thinks there is no pressure and it won't turn on to protect the AC pump. I always have to use the ''rest'' function on the climate control when I park the car for the night to dry the evaporator core. If I don't do that, the inside of the windows are fogged up really badly in the morning. In the summer days it's not that bad and I need the AC for cool air (I live in the Netherlands).

ptkacik

I met an MB engineer at an SAE convention and he talked about the need to run the compressor to better control the humidity in the car. Maybe air condition and heat simultaneously as he said it would cause sinus problems otherwise (stuck his finger in his nose??) and said this was important.

Peter

ptkacik

Does anybody have experience with an intermittent AC?

My ‘05 E320 CDI didn’t have air conditioning the other day. I turned it off and on but nothing, no cooling, no fan, no defrost. I turned it off and rolled down the windows.

Ten minutes later while driving down the highway, I tried again and it came back on.

A relay problem has been suggested.

Peter

ptkacik

Four other bits that may be related.

1. I didn’t cycle the ignition as I was driving on the highway so I don’t know if that would have helped.

2. A message came on saying the Dynamic Seats were being turned off (and they wouldn’t turn back on). The message was only briefly displayed and this may have happened in the past as I’ve found them off before despite never turning them off.

3. Due to the pandemic, the car is not being driven nearly as much as in the past. 235,000 miles total but maybe only 2,000 in the last year.

4. The two batteries are less than a year old. When I do drive it, it is probably for 50 miles.

Peter

ot1

a good chance the resistor as its sometimes called, on the blower fan is failing, its not really a resistor but instead an electronic motor controller. Go with the Behr one. About $100 at FCP.
not difficult to replace.

ptkacik

Thanks. That was a year ago and I did replace both the fan and the resistor. AND, it did solve the problem.

However, on rare occasion, the fan cuts off for about two seconds. Just as I get concerned that it has failed, it turns back on. I’m guessing it is a loose connector but it is so rare of an event, I don’t spend much time thinking about it.

Regards,
Peter