Hi, new to the 1991 300d ,

and I have been looking for vac leaks in the engine area and found two wires off
they sit behind the block, towards center back, next to a red circle under i think the manifold
hooked them up both ways L&R, R&L no difference and hooked or unhooked are they important?
also
more hours have been spent reading threads on vac that I'm sure that if I had a 123 and not a 124 I'd know or be closer to figuring this leak out but I'm still stumped(50k misquito bites also)
no dash switches work only defrost and side vents I thought they worked just before I bought it but I steam cleaned the enigne to see how bad the IJ pump leak was and forgot if they worked, my intrest was with this first
tried to switch the 4&6 pod lines in dash and got nothing
from anyone experince before dash removal where else can i look threads or advise ???
thankyou for your time
Howard

Welcome!

I have an 87 that also suffers from no center vents..can't decide if I want to go through with the repair

Anyway, here is a thread about removing the dash and replacing the pods on an 87 300d, I don't know that there is any difference between an 87 and 91. Someone else on here can help with that part!

http://www.peachparts.com/shopforum/showthread.php?t=35373&highlight=dash+removal

__________________
Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

You Will Visit this site:
http://www.w124performance.com/images/
(member GSXR's)

You Will Visit This Site:
http://www.detali.ru/cat/oem_mb1.asp?TP=1&F=124128_15S&M=602.962&GA=722.418&GM=717.437&
(Mercedes Benz Club of Russia maintains an up to date ILLUSTRATED parts
catalog)(on this site always choose the B[as in Bravo]M[as in Motor] option
the SM options show nothing)


You May Try This Site:
http://www.pauldrayton.com/uploadfiles/merc/Service/W124/Index/602_603index.html
(member Paul Drayton's version of factory service manual)

Are the wires to the block heater?
There is a vacuum port block for testing all the pods(+ Lines),you have to
pull out the glove box liner to get to it.

__________________
'84 300SD sold
124.128

no the wires come from a factory harness that go further back
have the glove box out no vac there... i think
this is where i tried to switch the 6&4 line to shutoff the defrost no luck

There's a device at the back of the injection pump that control engine idle speed. A round red plastic cover is the visible part of this device. With the wires unplugged, idle will probably be something like 500 rpm if the engine stays running. With the wires connected, idle should be 650-700 rpm regardless of load (AC, headlights, etc.).

Somewhere near the fusebox there is a cylinder about 2cm in diameter. It will have one hose from the engine side and two on the windshield side. Of the two on the windshield side, one will go into the cabin, one will disappear below the fusebox. Make sure both hoses on the windshield side hold a vacuum. If not, investigate downstream of whichever hose doesn't hold a vacuum. If both hold a vacuum, you'll probably have to remove that dash :/

Sixto
87 300D

ok dumb question
will the vents work if the AC is low?

WOW these are some nice links thankyou very much .

No relation between refrigerant and the vents. The vents are happy to blow uncooled air if the AC compressor doesn't engage. What the center vents won't do is blow any air if you set ACC for warmer air than is in the cabin.

Sixto
87 300D

thanks AC engages but too low to get cool
just a thought

Whoops! I stand corrected.The Vacuum Diagnostic Block [ Y-7] is located
"Above the passenger Foot-well" according to the FSM


JOB Number 83-620 "Checking flap control vacuum system for leaks"

Yeah, you're low on refrigerant...Is the system on r-12 or r-134 ?
(In any case,a set of gauges and leak detector is the sensible way to
work on the A/C...Anything else is the old Pinata action.)

Attached Thumbnails

 

__________________
'84 300SD sold
124.128

whew...lotta lines to follow
going to buy a mityvac but really dont understand how to use it is or are there any links or advise