center vent question-not the standard one. - PeachParts Mercedes-Benz Forum

rebreath · #1 08-21-2006, 01:46 PM

afternoon all...
started to track down center vent air lack and found a row of vacuum switchover valves behind climate control panel.#4 is non-functional.this has a green vacuum line(fresh air recirc I beleive).do I need this valve-it seems to be one that I cannot do without.Is this a dealer part only-is not listed in buy parts section.can I bypass effectively and still have normal funtion?

deerefanatic · #2 08-21-2006, 01:57 PM

You should probably replace it. It is known as a vacuum change over valve. Fastlane should carry it, but if not, the guy I always buy parts from, www.*************** has them for sure. Approx $35 give or take. $75 orders get free shipping........And he's a little cheaper than Fastlane too.......

I also have some used ones I might let go......Give me an offer and I'll consider it if you're interested....

winmutt · #3 08-21-2006, 02:00 PM

What model AC? AC II (aka PBC)? I have anything you need.

rebreath · #4 08-21-2006, 02:01 PM

Quote:

Originally Posted by deerefanatic

You should probably replace it. It is known as a vacuum change over valve. Fastlane should carry it, but if not, the guy I always buy parts from, www.*************** has them for sure. Approx $35 give or take. $75 orders get free shipping........And he's a little cheaper than Fastlane too.......

I also have some used ones I might let go......Give me an offer and I'll consider it if you're interested....

darn-gonna hit the yard first cause I have an 85 300D turbo That I have been stripping.I think there are still several of these in the car.If not though would you take 40 for two that work?I will check back later and let you know what I found, as i am heading out to the junkyard.thanks for the response.

deerefanatic · #5 08-21-2006, 02:03 PM

Sure, sounds like a deal to me.......email me at matthew@icsrepair.com if your need em and I'll send you a quote for the whole deal with shipping......

rebreath · #6 08-21-2006, 02:04 PM

Quote:

Originally Posted by winmutt

What model AC? AC II (aka PBC)? I have anything you need.

not sure-I have an 84 300D turbo.
btw-how do I get my car type to be attached to the bottom of these posts?

Brian Carlton · #7 08-21-2006, 02:56 PM

Quote:

Originally Posted by rebreath

btw-how do I get my car type to be attached to the bottom of these posts?

Press "user CP" at the top of the page.

Go to "edit signature".

Add your info.

Go all the way down to the bottom of the page and press "save signature".

winmutt · #8 08-21-2006, 03:08 PM

Quote:

Originally Posted by rebreath

not sure-I have an 84 300D turbo.
btw-how do I get my car type to be attached to the bottom of these posts?

user cp... dig around...

You should probably dig up the FSM and climate control testing procedures...

rebreath · #9 08-21-2006, 04:59 PM

Quote:

Originally Posted by winmutt

user cp... dig around...

You should probably dig up the FSM and climate control testing procedures...

did that which is how I got to where I am now.

rebreath · #10 08-21-2006, 05:02 PM

with four vacuum changeover valves from an 85 300D turbo.they look different(wish I had a camera),the 84(mine)is round,black with up nozzle and 90deg from it another nozzle.the 85 is about a third smaller and has same config are they interchangeable?

rebreath · #11 08-21-2006, 07:19 PM

Quote:

Originally Posted by rebreath

with four vacuum changeover valves from an 85 300D turbo.they look different(wish I had a camera),the 84(mine)is round,black with up nozzle and 90deg from it another nozzle.the 85 is about a third smaller and has same config are they interchangeable?

seemed to interchange fine,except for one small detail...inlet and outlet nipples were a different size.they are smaller on the 85.had to get creative to make a seal.now that vent works ,but,alas not center one ...yet!!!foundtwo interesting things and I am sure that someone here can tell me about them.
1-found a small brass filter"stone" in the 85 rubber bits from the boneyard.any thoughts....
2-running up passenger side and across behind glove box is a moderately sized rubber line(maybe an inchish ID).it does not run unbroken across dash(inside of course) roughly to right of center console and left of glove box it is separated by a foam tube(very dead btw)what is its purpose?can I sub something else for it?again any thoughts....

thanks for any help and/or advice.

carnut · #12 08-21-2006, 09:08 PM

I think you are describing the aspirator hose to the in car temp sensor located just above the two center vents. that hose takes the cars inside air and sends it to the programmer to compare in car temp with temperature set on the roller wheel of the automatic climate control. If that hose is off at either end the comparison will be inaccurate and the system will not modulate the temperature and fan speed accurately. With the glove box insert removed, reach to the left inside the dash were the hose connects to the sensor base. Twist the collar clockwise I believe and that should allow the sensor to lift up out of the dash. and if its disconnected there just push up on the hose and twist the collar to secure it to the sensor. Any leaks in that hose will cause the system to be slow to act or be inaccurate. There is a "thermister" in that little grille of the sensor that changes value electrically to modulate temperature of air discharged and which direction air flows i.e. dash or floor or a combination of both.

rebreath · #13 08-21-2006, 09:14 PM

Quote:

Originally Posted by carnut

I think you are describing the aspirator hose to the in car temp sensor located just above the two center vents. that hose takes the cars inside air and sends it to the programmer to compare in car temp with temperature set on the roller wheel of the automatic climate control. If that hose is off at either end the comparison will be inaccurate and the system will not modulate the temperature and fan speed accurately. With the glove box insert removed, reach to the left inside the dash were the hose connects to the sensor base. Twist the collar clockwise I believe and that should allow the sensor to lift up out of the dash. and if its disconnected there just push up on the hose and twist the collar to secure it to the sensor. Any leaks in that hose will cause the system to be slow to act or be inaccurate. There is a "thermister" in that little grille of the sensor that changes value electrically to modulate temperature of air discharged and which direction air flows i.e. dash or floor or a combination of both.

k,what does one use to replace that foam bit that connects that hose to the sensor.looked like it was originally several inches(6+)long.is this a part # part or a create-a-part

rebreath · #14 08-21-2006, 09:18 PM

1-found a small brass filter"stone" in the 85 rubber bits from the boneyard.any thoughts....

thanks for any help and/or advice.[/QUOTE]

any thoughts on the filter stone that I found in the line.is this a standard thing.

frankjnjr · #15 08-21-2006, 09:38 PM

Carnut: I replaced the aspirator hose to the in car air temp sensor. If I place a lighted match directly above the in-dash temp sensor grill and blow the match out, I would expect the lingering smoke to be drawn into the grill. However this does not occur in my car! Is there a way to determine if the temp sensor system is operational? The system was retrofitted w/134 by the prior owner. The a/c operates modestly well (center vent out-put) 40deg in a 95deg ambient at a steady 65mph. The heating system operates equally well with 120deg output at the side vents. The system appears to cycle the blower properly in both heat and a/c modes. I removed the pipe leading from the temp sensor where it enters the blower motor area thinking the disintigrated foam may have blocked the air passage. The pipe is clear?