Minor problems but annoying(A/C, sunroof, passenger window)
 

Hello everyone. This site is great, and I spent hours reading all the posts. First and foremost, I think that there is no substitute for a Mercedes. I bought mine used 4 years ago with 80K miles, and picked it over a 95 Acura Legend with only 42K miles because after test driving both, I couldnt see myself driving another car....

Well, after 4 years, and relatively no problems, those little things are starting to annoy...

Most importantly, the A/C. The AC blows out nice and cool, except that after the car warms up, the middle vents will cut out, and the air is diverted to the defrost vents...And they will come back on intermittently especially when Im at a stop light....but, as soon as I press the gas, they go out...Please help me with this problem(Im in Austin, and we have had 21 straight days of 100 plus weather) I had this similar problem last summer, and when I took it to the shop, they replaced the A/C filter, and it fixed it....needless to say, I replaced the filter this year, but it didnt help.

Secondly, the sunroof. It always sticks when it gets 3/4's closed, and when its closed, the pop up option doesnt work....any suggestions?

Lastly,(i promise)...The passengers side window...when you roll it down, it is loose, and opens crooked, like its not attached correctly to the remote arm....is it easy to get to? Or should I have the dealer fix it?


Thanks in advance. Im sorry for the long email.

The vacuum outlet control line to the A/C duct work may have a slight kink in it somewhere. I am trying to chase down the same problem in two vehicles in my garage at this time, also (vette and an SL).

I can't help you with the other problems. Good Luck.

Alright, I'd love to help you with your problems... but they don't sound too common!

A/C... I agree with southern son, could be a vacuum problem.

As for the sunroof, what do you mean it gets stuck 3/4 of the way closed? Does it go real slow the last 1/4 of the way? Or does it completely stop? And the pop up feature will not operate...
I would replace the sunroof switch and grease the sunroof rails.
Hopefully that will clear up your problem.

Your passenger window must be off track or something. The only way to find out the problem is to take off the door panel and investigate. The door panel is not too hard to remove.

Good luck and keep us posted.
:p

How can i get to it?
 

Where do I find the vacuum outlet control line? Would I look through the inside, under the passenger compartment by the AC filter, or do I have to go from the hood?

I was reading that problems with the relays would make the default setting go to defrost, which sounds like what my car is doing. Because it works fine for the first 5 or 10 min, and the AC blows out nice and cold, and the middle vents work fine....but after about 10 min, it begins acting up again, and it will until you turn off the car. You can start the car again, and the AC will work fine for another 10 min...If anyone knows what I can do, please let me know...thanks.:confused:

Reply
 

Thanks David for the reply. Can you or Southern son, or anyone for that matter help me with where to start looking for this vacuum problem? I am an amateur mechanic, and I do mean amateur...but I love working on my mercedes....Any help is appreciated on this AC problem.

The sunroof, the motor works fine on the sunroof, and it doesnt slow down, but it gets stuck at the same spot every time, and you have to reverse and then go forward again and it closes fine....when you close it completely, from the inside, the corner flap raises as if it is popping up,(could it be off track?), and when you hit the pop up button, it doesnt do anything(not even noise).

I will try to grease the rails this weekend to see if that alleviates the problem.


I will also attempt to take the door panel to investigate the window.


Thanks,
:(

Re: Reply
 

:( I am the same way! I would not have the slightest idea where to start looking for the vacuum problem...
As for the sunroof, I would get above the car and see if you can find any obstructions or anything? And definitly grease the rails (you should use Mercedes-Benz grease).

Try closing the sunroof using the convenience feature (key in door) and see if it closes any differently. This will help determine if you switch is *possibly* the culprit. Doesn't sound like it, but we might as well rule out all possibilities if you're stumped!

Good luck!


Also, the door panel needs 4 screws removed:
1 on trim by door latch,
1 on the bottom below the speaker
1 under the armrest
1 behind the door handle (must pop out plastic backing with flathead)
Then the rest is snapped on... you need to release these and then pull slightly upwards before pulling out.

Regarding the A/C changing modes on you after warm-up, I think there may be something else for which you should look. As most systems on M/B vehicles use the same type set-up I will tell you of something on my little '81 380SL. In the middle of the dash upper cover, between the middle outlet ducts there is a small vent like little sensor. Under the dash pad one will find a small duct that leads off to the right with a flimsy type little sleave. The purpose of this sleave is to send a good average of ambient cabin temperature to the sensor for temperature regulation. You may be able to remove the glove box (should not be too difficult) to look over at the sensor and see if the small sleave is in place. If not, reconnect or if it is badly deteriorated you can just put on some clear plastic tubing and lead it over to just under the glove box somewhere. This will enable the environmental control to function properly (hopefully). Don't get flustered, everything is an education. ;)

Thanks, my wife just explained we will be in Houston this weekend, so it looks like I will have to wait until late Sunday or Monday to try these tips...I will let everyone know how it goes.

By the way, I wanted to know if anyone had a set of C class alloys they would like to sell or trade. It seems my car has the alloys from a SL...I bought them new OE for 480 for the set....and would like to get the 8 hole wheels instead...

I am also saving up for a 98 or 99 E420, so I will have my car in the classifieds postings hopefully as soon as possible.



Thanks,
Carlos

Getting somewhere now....
 

Ok, I spent last night looking for anything out of the ordinary with the cooling system. I am afraid to say that I was unable to find anything that looked wrong with the AC system.I was not able to get in thru the glove compartment, it looks like it is one piece with the dash, so I was not able to find anything inside that might be responsible. If anyone out there has a C-class and knows how to get back behind the dash, let me know.

So the AC problem is still there, while I was messing with it last night, I did notice that the none of the airflow buttons seem to work(although the red led light is on when you push it), and the recirculate button doesnt seem to work. It used to kick the AC in high gear when you pushed it, now, its doesnt do anything...could this be related, or just a symptom to the problem?

I wasnt able to get to the window yet, but I did grease down the sunroof slides, and the sunroof doesnt stick anymore!!!! The pop-up feature is still not working, but at least the sunroof closes on the first try now.

Ok, for the A/C, we can find out exactly what codes you are getting. There is a procedure to pull AC codes from the PBU, via N22 read-out. This should help you figure out exactly what is wrong. Have a pen and paper handy.

1. Turn key to ignition position 2 (start mode, but do not start the car.)
2. Set the climate control to LO.
3. Simultaneously, press and hold the REST button and (front) DEFROST for atleast 2 seconds, or until dIA appears.
4. Press AUTO to go through each step/code. When numbers appear, record it, and pretty AUTO to get to the next one.

Once you have recorded all of the numbers, post them back on here and I will tell you what they mean. And feel free to delete them when you are finished, this way you can check back and see what codes are actually the problem. (IE... a code could have appeared once 3 years ago, and never came back. It will help us narrow down the problem.
GOOD LUCK!

Thanks David. Here are the codes I got from the display...I erased them once and they all came up again the second time I did this.

28°
62°
60°
80°
82°
10°0

I am not sure what these mean, but I hope each one is not a separate problem.

Thanks for your help, my friend thought that getting the codes right off the A/C was the coolest thing.

Carlos

Glad you were able to retrieve the codes, many time people have trouble with it... I can tell you another cool trick too!


28: Refrigerant Pressure Sensor (B12), CAUSE: Short Circuit. Intermittent.

60: A/C Compressor, Electromagnetic Clutch (A9K1), CAUSE: Short Circuit. Intermittent.

62: A/C Compressor, Electromagnetic Clutch (A9k1), CAUSE: Short or Open Circuit. Intermittent.

80: Switchover Valve Block (Y11/3), Tempering Flap, CAUSE: Unknown. Intermittent.

82. Switchover Valve Block (Y11/3), Tempering Flap, CAUSE: Short or Open Circuit. Intermittent.

100: Switchover Valve Block (Y11/3), Footwell Flap Long Stroke (80%). CAUSE: Unkown. Intermittent.


60 and 62 seems to be very similar... I am not sure what the difference between the two causes are or why. Look in the forum and you will see a post I started recently (A/C Diagnostics Codes). 60 and 82 are recurring for me also. They will come back after a day or two. I am still in the process of trying to understand what these explanations mean. I am kind of in the dark on that aswell. Now we just need SteveBfl to come along and help us out from here! I think that the "flaps" are related to the opening and closing of different vents, or the distribution.

You can also do other things with you A/C unit. With the car on and climate control on, press and hold rest for 5 seconds... you will then see the number "1" flashing across the screen and another number flashing (in cabin temp), they should be flashing between the two. Number 1 is the temperature inside the car. TO scroll to the other modes press the ARROW UP ('defrost'), and ARROW DOWN (feet). I can get you my list later. But briefly, 1 is in cabin temp, 2 is outside temp, 6 is coolant temp (F), 15 is in cabin selected temp, 21 is Engine RPMs, 22 AC Compressor RPMS, 23 is vehicle speed in kmh. Also, check 50 and 51 because they are related to the poly v belt. Hopefully they should both read zero.


Good luck and I hope we are starting to get somewhere!.

The early C-class had a recall on the sunroof as most of them failed due to poor design on the lifting angles up to chassis # 025776!
The most common reason the center vent closes under acceleration is a failure of the fresh air vacuum diaphram. Try using the EC button & if the center vent stays open you will know that the fresh air diaphram is the cause.

Ruled out alot of things.
 

Ok...I didnt delete all of the codes correctly last time, but this time I did, and it seems the only code that Im getting now is the 60.
I checked all of the temperatures from holding down the REST button, and they all seem normal. The A/C will blow cold air all day as long as the engine isnt revved. I sat in the garage(garage door open of course), and left the A/C on for about 15 min, and it ran fine with the car idling. But as soon as I took it out for a drive around the block, the middle vents cut out.
I tried just using EC as David suggested, but the middle vents still cut out.

Oh, and I found the tidbit about the recall of the 94 C220s and the tilt bracket...will the dealer replace that free of charge? Heres my VIN #
WDBHAZZE3RF059251

Looks like your car had the sunroof recall corrected.
Glad you are narrowing down the problem...

A/C problems.
 

David,

Where did you see that my car had the sunroof corrected? I think I will call the dealer today to see if they will replace the bracket.


Oh, I put in my VIN incorrectly...heres the correct # WDBHA22E3RF059251.

I deleted the old codes and now, all Im getting is the 60 code.

So it seems as though this is your problem:

60: A/C Compressor, Electromagnetic Clutch (A9K1), CAUSE: Short Circuit. Intermittent.

I guess that helps us since 62 was the same only the cause was a short or open circuit. So now we know that's a short circuit!


Your sunroof problem has ben corrected because your chassis number is AFTER 025776.

Hope this helps!
Good luck!!!! :o

A/c problems
 

I guess the replacement was just a touch better than the original. I guess I will have to take it in to have the bracket fixed. I hate to mess with the sunroof since for the most part it operates wonderfully now that the tracks have been greased. Ok, so now the A/C....Im only getting one of the error codes now, but I dont think the problem is in the compressor, because the A/C works great....even though the middle vents cut out(they actually just switch to defrost), the A/C blows out the same..in fact, the cabin still manages to cool down, although it takes longer because the air is coming out of the defrost vents. The side vents continue to work the same as well. I do think it has something to do with the flaps shorting out, and in the DIY section, I read that the climate control defaults to the defrost position when there is a problem with the climate control....I hate to take it to the dealer for what I think is such a small problem, and im thinking its a relay switch, or a vacuum hose somewhere that is disconnected or pinched....

I can't speak specifically for you model, but on most cars, the auto climate control uses the engine vacuum to operate. There is usually a 'one way' valve to hold the CC vacuum when the engine's vacuum drops.
On higher mileage cars, either the related hoses start to leak or the one way valve leaks. You open the throttle(in gear), vacuum drops, CC sees the lower vac and gets confused. Close throttle, vac up, works normal.

If you blip the throttle without load (not in gear)usually the CC will not be affected.

Hope this helps, Jim


'98 E320
'91 Miata Turbo 280hp
'90 Miata Turbo 230hp
'90 Audi 200 turbo
'93 Caravan

vacuum hose
 

That vacuum pressure sounds like what might be doing this....Because when it first started acting up, it seemed like the A/C and the engine were on a see-saw, and when the AC was working, the engine was idling, and when the engine was revving, the AC front vents switched to defrost...as soon as you let off the gas, the AC would switch back to the front vents...Now, after a few months, the vents take longer to come back on, usually when Im at cruising speed at 60 or 70, and let off the gas pedal....the front vents will slowly come back on....

But how do I check this? where would I find the vacuum hoses? are they inside next to the AC filter, or are they outside connected to the engine somewhere?


thanks for your help.

The C class gets it AC needed vacuum from the (central locking) vacuum pump in the right rear of the trunk.

It might be possible that somebody connected the vacuum line for the AC controls to the engine vacuum and that vacuum is not sufficient to control the vacuum valves involved.
There is a black plastic connector under the black cover behind the firewall at the right side of the engine bay and it might be possible that your AC vacuum is connected to that connector.
Check the vacuum pump in the trunk as well...you should be able to hear it pumping once in a while when you operate the AC system.
You are right about the default setting of the AC. AS soon as the car (and AC/heater) is turned off, the vacuum valves go back to their default position which is defrost (open vents along the windscreen and sides of the dash/side windows)

Does your C class have a vacuum adjustable ortopedic seat?

Ok....I will check the vacuum hose today...if my AC vacuum is connected to the engine connector, where should it be connected? or how can I test it?

As far as the vacuum pump in the trunk, I can hear the one for the power door locks....and it buzzes constantly...when the car is on....is there another one? Or is the one for the door locks the same one....I think there is something wrong with it because it is always buzzing, and shouldnt it only make noise when you lock the doors?

That is the one!!! And that is your problem!!!
If the vacuum pump is constantly buzzing, you have a vacuum leak in your AC system.
The vacuum pump in the trunk has 2 outlets; 1 for the central doorlock and 1 for the AC controls.
If I were you, I started in the trunk. If the AC vacuum line is connected to the engine's vacuum, the pump in the trunk still gets commands from the AC because of the faulty set vacuum valves...

Start by finding out where the AC vacuum is connected to and then start searching for a leak.

good lick & greetingz,

Yes, it should only make noise when you lock the doors, or change the air distribution with the climate control. It should not be constantly on. Are you sure it's always on? DOes it ever stop?

Ummm....thanks, and I actually might be the bonehead that switched the hoses...cause I got in the trunk vefore this problem started thinking that there might be short somewhere making that buzzing noise...and I pulled the hoses off....later when I reattached them, I think I might have screwed them up, because the first way I reattached them, the doors locked down tighter than ft knox!!!! I would have been in trouble had the trunk been closed....so I might have inadvertently screwed up the pump....but, at least now I know where to look....Ill check the connections and if that seems ok, Ill trace the line to see if I can find the leak....

THANK YOU!!!! I will let you know how it goes...

;)

David,

No, it doesnt buzz nonstop....there is a 5 or 10 second gap....kind of like if someone is playing with the locks...but the locks dont move....I think its always done it to some extent, I thought it was the power antenna until I traced it to the back fender well in the trunk on the opposite side....It even made the sound after the car was off, and the doors were locked...

I guess if the whole unit is bad, I can order one online here....I hope they arent too expensive....Ill check tonight to make sure its not the actual hose...

BTW a 'minivac' would be very helpful finding the leak. It is a handheld devise that create vacuum and has a vac gage. Lots of adaptors included. You can find at autoparts store.

Good luck, Jim

Well, the code 60 I wouldn't worry about. I am sure it's related to something else. I get 60 too. That code just keeps coming back also.

Let us know how it goes with the vaccum pump! I hope this solves your problem! I am sure it will.

:D :D :D

Now we're getting somewhere!
 

Ok, thanks to everyones help, and countless posts...I am very close to fixing this thing. I think this vacuum pump has gone bad. I took it apart, and it doesnt look that great inside...so, now, I tried to find the part (202 800 12 48) here on the parts shop, but they dont have it....does anyone know where I can get one...and cheap if possible...perhaps a used one? Thanks in advance.


Carlos

Carlos,
Call the number on the top of the screen!! Ask for phil he will help you out.
Good luck!

I was busy last night. I cleaned out the vacuum pump, and it seemed to be operating ok. so I tried testing the line...whenever I had the climate control hooked up to it, it would work for about 10 seconds right after you started the AC(i guess trying to open the flaps) then it would stop, and then it would come on for 3 or 4 seconds every 10 seconds....like if there was a leak in the system.

So then I thought it might be in the line, or on the other end. So I found out where the line comes out (under the hood, right in front of the passengers seat). The hose connects to a small black box that has a lot of other connections on it, which I believe are the controls for the other vents. When I went to test the connections, the green hose's nozzle broke off(I swear I barely touched it!). So now I have a new problem....or do I? Because after it broke off, I checked the connections, turned the AC on, and guess what? The middle vents didn't work at all!!!! The only thing that wasn't connected was this green hose....So, I think that there may have been a crack in the nozzle, and that's where the leak was. So, today, I have to go by the Mercedes dealer to get a new nozzle....anyone have a trick for fitting these things...I couldn't even get the piece that goes in the hose off because its practically welded on. I ended up cutting it right where it ends on the hose.

Now my middle vents don't work at all, but the vacuum pump is also not turning off and on....so I think that's where our trouble is....As always, I will keep you posted.

I also took the time to take the door panel off last night, and found the problem with the window. One of the white brackets is split...shouldn't be expensive, but I wonder how hard it will be to take the window off of the sliding mechanism?

All in all, despite the small headaches, my car has been less of a headache than the Audi, Volvo(740 turbo), and Honda Passport I have had in the past.

ITS FIXED!!!!(I KNOW, I CAN HARDLY BELIEVE IT MYSELF)
 

Its fixed guys...thanks...total cost for AC repair:

$1.98.....yep...under 2 bucks!!!!

I traced the line last night to where it went into the black box under the hood....and that green nozzle that broke off last night that is in my last post was the culprit...I got the nozzle today and replaced it in about 2 seconds...took my car out in 104 degree Texas weather, and the middle vents stayed on, and the cabin temp dropped to a comfortable 71 degrees....


Thanks to everyone...

The bracket for the window was 86.00 at the dealer, so needless to say, I said forget it...they only sell the entire assembly, and all i need is one little plastic bracket.