W202 '95 C280 remove dash? (vac pod) - PeachParts Mercedes-Benz Forum

unkl300d · #1 09-10-2010, 01:55 PM

My '95 C280 had groaning noises periodically from the aux. vac pump located in the rear passenger side.
That lasted months and stopped only to develop a high pitch 'whistle' from the passenger side front area toward the right.
It is periodic and can be made to stop by pressing the EC (economy) air setting or any other climate setting.
All the vents work properly and the rear head restraints drop when the dash button is depressed. (supposedly this is a test for vacuum).

Apparently the recirculation/fresh air pod (element) has a tendency to leak and this may be the source of the 'whistle' noise.

Does the dash really need to be removed to access this part? I believe it sits behind the glove box air bag. (?)

Is there any liquid spray that can be injected to stop a pin hole leak in the diaphragm, assuming that is the problem??

Does the dash come off as one piece or is it compartmentalized?

Your opinions are appreciated. I did not find answers in the archives.

Thanks.

mbdoc · #2 09-13-2010, 08:43 AM

Very common problem!

In San Fran. I would suggest blocking off the vacuum lines going to that vacuum element & then see if the system has the cooling capacity that you need.

Takes a "good" dealer tech about 5-6 hes to replace that element.

unkl300d · #3 09-14-2010, 12:33 AM

Thanks M.B.DOC ! that sounds like a great idea !

here is what I got at benzworld this evening.

http://www.benzworld.org/forums/w202-c-class/1230237-w202-common-problems-their-solutions-2.html

and more specifically the '95 C280 dash removal and vac line testing...

http://www.zadefaraj.com/dashboard.htm

thanks to zadefaraj as well !

vince · #4 09-14-2010, 08:06 AM

I had the spring break for the recirc door on my 1995 C280 so I had to access the flap assembly. I pulled the dash. I didn't find it that difficult. The info on the W202 CD was accurate and very helpful. I think it took maybe 6 hours total and I was being slow and careful (so I'm surprised a dealer can't do it faster). One caution with blocking the vacuum line. If the door drifts to the closed (full recirc) position, the windows will fog up fast - it is just scary.

unkl300d · #5 09-15-2010, 02:42 PM

Good info ! Thanks.
My front vents operate well. All the vents and pods seem to operate.
My problem is with a high pitched sound coming from passenger side.
I was told the vac element can have a pin hole in it.

If I leave the air system ON all the time or on Economy, the noise is eliminated...

can vac test be done using the vac line 'junction' box in the engine compartment by the passenger side firewall or only from the 'junction' box inside the glove compartment rear???

mbdoc · #6 09-16-2010, 08:11 AM

The a/c vacuum switch-over valve is above the under dash panel on the passenger side of the dash.

Simple job to remove that panel & access the vacuum valve.

The green/blue vacuum line & the "dark red" vacuum line both go to the recirculation vacuum element.

unkl300d · #7 09-17-2010, 07:20 PM

Thank you M.B. DOC