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Discussion Starter #1
Is there anyone out there who might be able to diagnose climate control not working? None of the settings do anything except make a hissing noise for a second. No air comes from the vents at any temp setting. Is this a fan issue or vacuum? The door locks all operate slowly, but even after sitting for a week. The brakes are fine, transmission shifts fine. There is oil on the floor on the driver's side. When I lift up the carpet there is a tube covered in oil, could that be from the brake booster? Could this be contributing to the a/c problem. The car is fully charged with freon. It has been inop for about a year. Thanks!
 

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1982 300D Turbo
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take off the the panel underneath the glovebox, u know on top of where u put ur feet. on the pasenger side. The blower motor is in there turn the fan on hi and hit the fan a little bit with ur hand and see if it starts turning. sometimes they get locked up from siting for so long, and the brushes in the motor coould be bad. Thats what happend to mine...

MARSH
 

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1980 300D
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I've been there. The oil on the floor is from your vacuum shutoff valve leaking oil into your ignition switch via vacuum lines. The oil has probably migrated into your vacuum controlled climate control but not yet into your door locking system. By removing the glovebox liner and the valance panel below the dash you will be able to view all the wonderful vacuum modulators that control your climate control - there are several- as well as the ignition switch. There are also modulators by the accelerator pedal as well as buried in the top part of the dash. They are pink. Check them with a vacuum tester. If they leak, you can get new rubber from George Murphy at Performance Analysis in Georgia for a few bucks or spend about $50 each from a dealer. They are BEHR parts. For a quick fix of your ignition switch/pants oiler, unhook the vacuum lines at each end and remove the oil. You will still have to replace the vacuum lines and shutoff switch, but you will be able to drive to a parts store for more vacuum tubing without getting your pants dirty. Be sure to have beer on hand, as it requires patience.
 

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Discussion Starter #4
Hey Douglas,

Thanks for the tip on the oil leaking on the floor. I just inherited this car and I'm not too familiar with diesels... I bought a vacuum gauge and I should test for leaks near the gas pedal or at the valance under the glove box? And the vacuum line that needs to be replaced is the one that runs under the carpet on the driver's side? I need to find out where exactly that it runs to. Looks like it goes from left of the brake pedal, rearward, and towards the pass. side. I havent traced it any further incase I was barking up the wrong tree. So this vacuum line is what causes the a/c to blow at any temp? So the problem may not be directly tied to the blower motor itself? When I push the buttons for vent/floor/defrost, etc...I can hear something inside the dash shift like air hissing, but when I push any mode for the fan, I just get a "click" for a second. No air. If I put it on ECON and drive over 40mph I get a little flow through the vents but not much. Could you walk me through it if you have a moment? THanks!
 

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Discussion Starter #5
Hey Marsh,

Thanks for the tip. I will try that asap hitting the motor with my hand. So you don't think it's a vacuum problem that Might be keepign my blower motor from operating? I'll try this first before tackling all these vacuum lines and replacing the oil covered ones and I'll let you know what happens. Thanks again...
 

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The vacuum system has to be working or the climate control vacuum modulators won't 'power up' the system. Mine would only blow defrost. When I found a leak in one modulator and fixed it, bang, presto, the entire climate control system worked. When you remove the panels below the dash, along with the glovebox liner, you'll get a pretty good view of the vacuum lines - including the bundle that runs from the mutant climate control 'brain' in the engine compartment. ALL those vacuum lines need to be checked. It will serve you well, if you're up for it, to remove the center dash panels and see and check all the vacuum connections. There are a lot of them... The blower housing, under the glovebox, is held in by just three screws. The motor will drop out. Easy to check. The vacuum lines that run to the ignition switch run right through the bulkhead to the splitters by the master cylinder. When all leaks are fixed the system works pretty well, sort of. The slight hiss (whoosh?)of the doorlocks settling is amusing to passengers.
 

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Discussion Starter #7
Douglas,

Thanks again I'm starting to get a better picture of this...but I noticed something new...aside from the oil on the driver's side floor, I accidently ran my hand along the bottom of the dash under the steering wheel and my hand got covered in black oil. Is this leaking from the ignition?? Eek!! What components would need to be replaced so that oil is not entering the cabin?? Thanks sooo very much i'm going to try to tackle this project over the weekend!

Paul
 

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Does anyone Know where I can obtain this vac shut off at the injection pump?? I assume the lines that are full of oil will need to be replaced too? Will standard vacuum line from parts store suffice or does it need to be the more rigid line, if so where would I obtain it from?? Thanks again!
 

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He's correct. Vacuum shut off valve and new vacuum lines that lead to the ignition switch. And rubber fittings for vacuum line connections. You should only need a couple of bottles of beer.
 

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The same thing with my car. The blower doesnt work. I took of the cover, and hit it with my hand and it worked. I parked the car, came out a few hours later and it stopped working. How long does it take to put a new blower motor on? I have on in my old car Ill just take off. Is it a bitch to do?
 

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1985 300CD - 4/17/2005 10:26 AM

The same thing with my car. The blower doesnt work. I took of the cover, and hit it with my hand and it worked. I parked the car, came out a few hours later and it stopped working. How long does it take to put a new blower motor on? I have on in my old car Ill just take off. Is it a bitch to do?
Save yourself some time and just hit the cover with your hand when the blower won't come on. It works every time.
-Joe
 

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Discussion Starter #14
I found someone selling just the a/c fan motor online for about $80 new. Problem is it doens't come with the cage fan, and I can't seem to pry mine off the old motor. I checked around and these things are really expensive...any ideas on where to get a new motor/fan combo? Anyone have one for a w123? I seem to find a bunch for the 126 but not mine. Anyone know where to get the vacuum shutoff switch that is leaking the oil into my dash too? THanks in advance!!!!
 

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Most of the time it's the brushes that wear out, and you don't need an entire new fan motor. I believe you can get them at a local hardware store for less than $5. Just make sure of the size. I can't tell you more about it, but perhaps a search on it might help. If you want, head over to Mercedes Shop forum. It's been covered dozens of times with the specific size. Goodluck!
 

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Douglas, I have a 84 300TD with 64,000 miles and I'm relatively new at repairing a Mercedes. I restore old vettes as a hobby so I have the skills to repair most anything. Read your post on the climate control problem and it seems to describe my problem. I have the oil leak that is described. My center vents do not work and I have the video for pulling the dash and repairing the center vents and diaphram repair kit. Seems while I'm in there I can rebuild/replace the modulators you describe and the hoses. My sense from reading different posts is that eventually all of the modulators may have problems.

First off, where is the vacuum shut off valve and how do I rebuild/replace it to prevent the oil leak? Presume it is in the engine compartment but I can't find it in the Haynes manual (useless) or the Mercedes repair CD.
Second, you mentioned Performance Analysis as the source for the rubber seals. Would you recommend replacing all, and if so, are they all the same?

From your post, it would seems I would repair/replace the shut off valve first, replace the rubber in the modulators under the dash and then replace the vacuum hoses. Does that sound about right and is that 6 or 12 beers???
 

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dtabler - 5/21/2005 10:40 AM

Douglas, I have a 84 300TD with 64,000 miles and I'm relatively new at repairing a Mercedes. I restore old vettes as a hobby so I have the skills to repair most anything. Read your post on the climate control problem and it seems to describe my problem. I have the oil leak that is described. My center vents do not work and I have the video for pulling the dash and repairing the center vents and diaphram repair kit. Seems while I'm in there I can rebuild/replace the modulators you describe and the hoses. My sense from reading different posts is that eventually all of the modulators may have problems.

First off, where is the vacuum shut off valve and how do I rebuild/replace it to prevent the oil leak? Presume it is in the engine compartment but I can't find it in the Haynes manual (useless) or the Mercedes repair CD.
Second, you mentioned Performance Analysis as the source for the rubber seals. Would you recommend replacing all, and if so, are they all the same?

From your post, it would seems I would repair/replace the shut off valve first, replace the rubber in the modulators under the dash and then replace the vacuum hoses. Does that sound about right and is that 6 or 12 beers???
I am not Douglas but I an answer some of your questions.
The shutoff valve is on the injector pump on the end closest to the driver. You will see a vacuum line going to it from the fire wall and it is metal. There are four bolts holding it on. When replacing check to be sure it catches on the inside by pulling back out and feeling for resistance. About an half hour job and very dirty unless your engine is as clean as Kraugs. I would check the valve by substituting the vacuum line with another and place vacuum on it to see if it works. Use a mity mite or suck hard.
 

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Thnks for the info. I located the shut off valve, the vacuum line going to the firewall. A few more questions .... what is the unit on the firewall?? (it has an electrical connection). Is it from the shut off valve through that firewall unit that the oil is getting into the system?? Last question: (and this will sound dumb), when I go to an on-line parts place to see how much a shut off valve will cost, I find one under diesel injection by that name. But it does not look like the right thing and it says it's function is to "pull the injector pump rack to stop". Tried looking at everything connected with the injector plus anything with the word "vacuum" but no luck. Cost was $57.00. Am I off track?

Appreciate your help.
 

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dtabler - 5/22/2005 8:23 PM

Thnks for the info. I located the shut off valve, the vacuum line going to the firewall. A few more questions .... what is the unit on the firewall?? (it has an electrical connection). Is it from the shut off valve through that firewall unit that the oil is getting into the system?? Last question: (and this will sound dumb), when I go to an on-line parts place to see how much a shut off valve will cost, I find one under diesel injection by that name. But it does not look like the right thing and it says it's function is to "pull the injector pump rack to stop". Tried looking at everything connected with the injector plus anything with the word "vacuum" but no luck. Cost was $57.00. Am I off track?

Appreciate your help.
Will try to find a cheaper one but that sounds right for one from an online store. Look on EBay for one.

Don't know what the electrical box is, must look it up.
 

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Just need to make sure I have things right after reading a few older posts .... the oil we are talking about is thin and clear, and is caused by a leak from the vacuum shut off valve, right?? I have not heard anyone say where it comes from and given it's not black, its not motor oil and does not smell like break fluid. If the center vent diaphram is bad, I presume it will impact the entire climate control vacuum system?? Sorry for the additional questions but I'm trying to get as much info as I can on anything else I might need to repair before pulling the dash and fixing the center vents.
 
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