The lower ball joints should be fine, they are lemforder ones that were replaced 3 years ago, the upper ones I know were too cheap. But the wheel bearings could be part of the problem too, I can't tell. The radiator in the car looks like it was replaced at least once, I know with the Alfa I used to have a new one made a huge difference. The problem with fixing the heater blower is I don't even know where to start to figure out what's wrong. Someone has obviously done a hack job to try to make it work, so I don't even know how it was supposed to have been or what didn't work to make that necessary, or even how to take the dash apart enough to see what they did, or how to tell what is broken or has been changed.

The heater blower motor on the W126 is simple to remove and test. Romeve the carpeted panel just below the glove box. Then remove the plastic cover you will be looking up at while standing on your head in the passenger floor. At that point you will see the blower motor. It falls out in your hand when you remove the three (IIRC) screws.

Check to see if you can spin the blower by hand. If not it's toast. If so, test for 12 volts at the connector with the climate control set to econ and hi fan setting.

Regarding replacing the SD with another used car... Remember, the cheapest car is usually the one you already own. I will add, if you dislike the SD find the car you really want and dump money into it.

The W126 SD is pretty hard to beat. Easy to fix, abundant supply of parts and very reliable if maintained.

I have asked a couple times about the climate control problems and no one ever answered.

I don't believe that the heater blower is even wired to the climate control anymore. I guess I can take it out and see if there is power to the plug when it should be on, but I doubt it.

I can't speak to why they didn't answer. Maybe because the question was kind of broad, and it's one of the more complex systems on these cars to diagnose.

But! If you search online there are resources for doing that diagnosis. And just like the vacuum system the diagnosis is the hard part. The fix is usually simple; i.e. in your case either a working used climate push button unit, a good used blower motor, or a re-manufactured blower regulator, none of which are especially expensive or hard to replace. Just some screws to remove and plugs to unplug.

But again, do you want to spend the time doing diagnosis? We can't force you to. You have to want to.

You could always continue the hack and just add a switch to turn the fan on and off.

The mercedes climate controls are kind of a pain because they are aging high end with tons of options.

However, just as an example of similar kludge stuff, lots of times switches like that get installed by people who dont know or dont care about fixing it right and looking for wiring diagrams.

I cant tell you how many times ive pulled some nasty witing out of a car that was a "fix" based on someone not having a voltmeter or a diagram.

When i first bought my van, some bonehead had done exactly what happened with your SD, wired in a toggle to run the blower. I used that till it fell off being crappily wired, then discovered that all i needed was a 4 dollar blower switch, and it was fixed like new.

On another incident someone had put in a push button starter because the car wouldnt start. Turned out to be a burned out fusible link, which they didnt have the data to look for, or apparently the equipment to test.

You can go a long way with a diagram of how it was supposed to be done factory, and a cheap volt meter that will let you measure battery voltage and continuity.

I would like to fix it, but I honestly don't know how to fix things that I don't have a pretty good idea of what I'm going to do before I start working on it. Rebuilding the suspension or replacing brakes, etc is pretty easy, you can see how its put together and you just replace old parts with new and put things back together right.
Figureing out how someone rewired the heater blower motor and what broke in the climate control system to cause them to do that is way more difficult than anything I have ever fixed before.

I sympathize with you not getting an answer when you posted a question. Sometimes it is just an accident of timing, the right people are not logged in to answer. I have had to repeat questions before in order to score a response. And, as uberwasser points out, the cc system isn't the easiest topic.

I am assuming the blower 'fix' now in place I involved jumping power from another source. If that is the case, is the original wiring all intact? You should be able to tell that by removing the glove compartment and lower trim.

Assuming the correct wiring and connector are there, and there is no power coming through, the usual suspect is the climate control unit itself (the dash control pod). These suffer from broken solder joints from old age, but also can fry internally if the auxiliary water pump under the hood seizes.

I am no climate control expert, but that much is pretty common knowledge on these cars.

This one got plenty of replies:

http://www.peachparts.com/shopforum/diesel-discussion/339836-how-realistic-fixing-c-83-300sd-2.html

Thanks for everyone replying and trying to be helpful, but I think I need to just give up on this car and get something else as soon as I can, and not expect to get more than a couple hundred dollars for this one.

Where are you? I'll give a couple hundred site unseen if it drives and shifts. Bring it by and I'll give you a ride home.

83w126,

Last weekend, I went shopping for a used car for a friend's girlfriend. She has been and still is driving a 2001 Dodge Intrepid with the fluids mixing for quite some time. The car has 180K on it and that is pretty good for that car. It obviously was not well maintained, though. We went to about 12 car lots and anything under $4K was junk and anything $4K to $6K was fair but still not nice. LOTS of repaired title cars and cars that had been repainted and in accidents. The car lots do a good job of hiding these issues to the untrained eye. One place wanted $5K for an old Focus that had a bent unibody. The doors would not even close properly. The best car I saw all day was a little 2002 Suzuki Forenza for $2000 with 102K. It had some accident repair but it was well done. The car still needed some sort of sensor and several interior bits repaired. Side note - It is amazing what you can find in the glove box - accident reports, repair receipts, etc.

My point is that you will be trading one problem for another if you stay in your stated price range. I tell my friends "buy new or buy reliable." 10-15 year old cars need just as much or more work than your 300SD. I can guarantee you that the 300SD is going to be much easier to work on than anything 10-15 years old. Ever heard of a "swirl valve controller" on a 300SD? Me, either. If you want to buy newer, you will have to learn a lot more than if you keep and fix what you have now. Don't be penny wise and pound foolish!

Learn. Read. Implement. I used to take my 2003 Sentra to the dealer for every single oil change and checkup that was suggested, while in my possession. It did not stop the electric cooling fan motor from seizing up and eventually blowing the head gasket, due to overheating, under the operation of an inattentive driver. The repair cost was $1500. 5 years ago, I knew very little about automotive repair and had little interest in it. I just brought whatever problems I had to the dealer and bent over. Now, I wouldn't think twice about rebuilding the front of my W126 or resealing the steering gear box or rebuilding the A/C system. You know where I learned all of these skills? Right here, on this forum.

Well said, eaton
 

Exactly.

When I hear people splitting pennies in arguments over the value of an old Mercedes advertised for sale, I shake my head. You cannot get a used diesel VW around here that is worth bothering with for under $5k, and those don't come up that often. Usually double that price is the entry level.

Even when I set a search on the local ads at $10k, precious little in any reasonable car comes up.

Unfortunately, however, it looks like the ship has sailed on the OP addressing his car's issues.

I haven't really decided what to do with it, I just don't like the idea of spending another few thousand dollars on it while still ignoring the problems I can't fix. I did that with the Alfa I used to have, I ended up fixing almost everything that didn't work anymore and spending thousands of dollars in it, but I could never get the high beams or heater to work and I realized I just didn't want it anymore and sold it for $900.