While driving to work this morning a rock from a dump truck went through my head light lens on my 84 300SD.
I just looked up the part on this web site and could not find any parts that look like the one on my car. ( I"m not sure if there called a lens)
All they have is frames and sealed bulbs. I also looked in my performance products catalog with no luck.

Now for the next question my heater blows hot air all the time.
It comes out the dash vents and the defroster vents.
It seams to stop blowing when the car comes to a stop .
When the car picks up speed the hot air comes back on.

Thank in advance, Pete

RE: headlight. A picture would be helpful. I suspect you have Euro headlights. Search for that term, maybe you can find a pic on eBay or somewhere.
You can order Euros from Puma:
http://www.puma-access.com/hella/hella.html
Did you get the license or truck owner's name? They will pay if you report it, o/w your out a few bucks I suppose. I always dread catching a rock on my Euros. On the W124 Euros run almost $250 a side.
RE: heater problem. Welcome to the gremlin called Mercedes Climate Control!
You probably need to have some diagnostic work done, if what you say is true. The heater fan running up and down in accordance with engine speed, is well, I dunno, strange to me, unless the battery voltage is varying a lot.

There is a mono valve that usually sticks closed, its possible yours is open all the time allowing hot coolant to circulate. The climate control uses a module that is an analog circuit assy, connected to the mono valve, a small circulation pump, and the dash mounted control board which lies behind the push buttons. The latter items is known to have relays that stick or fail to make contact and it has solder connections that get fatigued and need to be resoldered.
The CC system is a system takes a bit of work to understand before any troubleshooting will pay off. Shotgunning components is not recommended unless you have access to known good testing modules. Goodluck!

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Please clarify this a bit.

Did the rock penetrate the plastic "headlight door" that is around the headlight, or did it actually penetrate the glass of the headlight itself?

Do you have the removable H4 bulb? Can you remove the bulb from the back of the headlight and replace just the bulb?

After clarification, I'll send you in the right direction.

Just cries of a torn monovalve diaphragm...

Might be a good place to start looking. Very simple to pull the guts out and take a peek. Right next to the battey in an SD, 4 small screws hold the top on. Remove screws and lift on silver shaft and the guts will come out. Do this gently and you can keep track of where they all go to put it back together too.

If the little rubber diaphragm on the bottom of the shaft is torn you cna get a replacement "monovalve repair kit" at Fastlane on teh top banner of this site. great service and only about 30 bucks to fix.

if you want more info then search this forum for monovalve repair. Lots and lots of posts on the subject.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Boy, do I wish we could put this to bed.

I, and several other members have suffered a torn monovalve diaphragm and damn near froze to death. Effectively, no heat whatsoever.

But, the monovalve supposedly fails in the open position.

So, is it possible that the monovalve is not getting any signal from the CCU, or the solenoid in the monovalve is not operating?

I cannot see how one of us can have full heat with a torn diaphragm while others have none.

When mine failed it was full heat all the time. It was crusted to the point that I couldn't believe that it even worked to move up and down.
Maybe this is part of the reason why some fail open?

I have always been led to believe that the default on these is full heat and defrost if you have a power and vacuum failure...

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

I understand this to be true as well. However, on the SDL, the valve was perfectly clean and the operation of the valve was entirely proper. The only issue was a small tear in the diaphragm. Apparently the coolant gets above the diaphragm and prevents the diaphragm from travelling upward to allow coolant to flow.