PaulX608

OK, I knew it would eventually happen. When I bought my 400E last May, the refrigerant was low. Not so low the pump didn't cycle, but it wasn't cooling effectively. It had 73000 miles at that point. I added a can of R134a and it worked fine all summer. This Spring at about 90000 miles, I noticed it wasn't cooling well again. Once again, it was low, so I added a can. I thought to myself at that point that if it took 1 can a year at $10 and didn't get worse, I'd just live with it. Well yesterday, now with 98000 miles on the clock, it was blowing hot air. Low again. Got a can of refrigerant, worked on the way home and seemed OK this morning. This afternoon, dead. System has lost all pressure, pump obviously no longer coming on. I won't be able to start looking for the leak until this weekend. I'm gonna pull out the fan so I can see the evaporator and charge the system with some leak finder dye in it. I guess my question to you guys is where should I look for the most likely leak points? The faster I find it, the sooner I can replace the bad part(s) and get cooling again. It was 100°F today, and I really hate going without A/C. Any guidance would be greatly appreciated.

shdoug

My condolences, Paul. I've heard that the evaporator (buried in the dash) is notorious for developing a leak in these cars. It is a very difficult and painful job if you DIY. If you take it some place, they will charge you 2 arms and a leg.

The other likely place for a leak is in the condenser in front of the radiator. If the leak is there you will usually see an oil streak where it originates and this usually shows up well due to the collecting of dust and dirt on the face of the condenser.

Visually inspect your hoses for leaks and look at the areas surrounding the compressor for spray patterns. If the leak is a large one then you are undoubtedly losing refrigerant oil as well and it is visible.

At least Heaven is air conditioned!

PaulX608

I actualy hope that it's the evaporator/expansion valve. I've replaced my blower fan, and have exposed that area before. Also, that assembly seems to be the least expensive fix. I've inspected most of the parts that are more easily seen, and haven't seen the leak. As you say, as large as this leak seems to be, I should see oil. I did get a funny smell out of the vents the other day. Kind of like the smell when you open a new box of Band-Aid® strips. I'm sure I'll find it, it'll just be a huge P.I.T.A. The biggest trouble is that I currently have no garage and no spare car. I'm going to have to take all this crap apart, find the leak, put it all back together, order parts, drive the thing sans A/C all next week, then do it all again next weekend. And my luck, I'll find the next weakest point in the system in a couple months, lol.

ksing44

My first leak was at the expansion valve and now my second leak is the compressor. I hope the next time it will not be the evaporator!

Do all AC systems suck, or is it only Benz? I’ve never had problems before, but I never owned a car for more than 10 years before either. It will be interesting to see if my wife’s Honda ever has an AC issue. It is 5 years newer than my car, but with about the same number of miles (100K). It has never had any problem at all! No AC leaks, no head gasket leaks, no deteriorating wire harness, no transmission issues, and it didn’t even need a water pump yet. The Honda has a truly amazing repair record.

shdoug

My dad's '85 Accord developed a leak in the condenser around 250,000 miles and it was 15 years old. The only repair work that had been done to the car by that time was:

2 timing belts (water pumps changed for prevention)
Radiator replaced
Blower switched replaced
Valve cover gasket

It still ran perfectly when it met its demise- a Buick that stopped short.

The Germans have a loooong way to go when it comes to making a car last.

PaulX608

Well, after some underhood disassembly, I found my leak, and it is indeed the evaporator. Unfortunately, it doesn't come out from that side. From the research I've been doing, the entire dash has got to come out. This will have to wait until my house is sold and I move closer to work. Then I'll have the time and the space to do it correctly. I'll post some pics later.

ksing44

[QUOTE=PaulX608;2298902]I found my leak, and it is indeed the evaporator. Unfortunately, it doesn't come out from that side. QUOTE]

I am very sorry to hear about your problem. If it is any comfort, which I doubt, you are not alone. It didn't happen to me YET, but sooner or later I guess it will be my turn too.

Hey, look on the bright side, at least you have a big bad V8 and it may have been built before they went to biodegradable wiring harnesses. Then again, I have read that V8 gets pretty hot under the hood and that the wiring may still go bad. I have also read that some 93 engines do have the bad wiring. I don't know what I am talking about. I guess I am just trying to make you feel better, even though I may have failed.

Good luck with your car!

PaulX608

Well, here's a couple shots from my adventure this AM:

After a bit of underhood disassembly.

There's the culprit!


And yes ksing44, it's real nice to have the v8. Even without A/C right now, this is an awesome automobile. Plenty of power, quiet, comfortable, and it gets 24mpg on the highway!

And shdoug, the difference between these and the Accord is that the Buick that stopped short wouldn't end the life of a W124! These cars have their issues, but those things can be fixed. The car itself should last forever with care.

shdoug

With care and lots of $$$$! I can think of about $3,000 worth of repairs to make to mine right now, and it wouldn't even look any different when I got done with it.

You're right about the Buick! I slammed into a car in mine on a patch of black ice and the damage was only cosmetic. It is a tank. I love the W124- I just wish I had the kind of cash it takes to keep it tip-top.

ksing44

Me too!!!

ksing44

So close, yet so far. What were they thinking when they made it so hard to replace. Just think how great it would be if you could simply reach up from under the car and replace that thing.

PaulX608

****, I'm half tempted to cut that sumbich outta there from that side! I can patch the damn hole!!

shdoug

[QUOTE=PaulX608;2296950]I actualy hope that it's the evaporator/expansion valve. I've replaced my blower fan, and have exposed that area before. Also, that assembly seems to be the least expensive fix. I've inspected most of the parts that are more easily seen, and haven't seen the leak. As you say, as large as this leak seems to be, I should see oil. I did get a funny smell out of the vents the other day. Kind of like the smell when you open a new box of Band-Aid® strips. I'm sure I'll find it, it'll just be a huge P.I.T.A. The biggest trouble is that I currently have no garage and no spare car. I'm going to have to take all this crap apart, find the leak, put it all back together, order parts, drive the thing sans A/C all next week, then do it all again next weekend. And my luck, I'll find the next weakest point in the system in a couple months, lol.[/QUOTE

How sure can you be that this smell is related to the leak? Yesterday I started getting a funny smell, too. I don't know what band aids smell like, but I bet this is it. Reminds me of an old person's house smell. I was an HVAC tech for years and this does not smell like refrigerant oil to me. What do you think? So far it is not low on charge. There's no way in Heaven or earth I'm paying $1200 to fix it. I would probably charge it up and trade it in... or just drive it that way like they did 50 years ago.

ksing44

My 1995 E320 smells when the AC is off and I am just using the economy selection. For me it is just an old stale air smell. I need a new compressor, based on having green dye all over the thing, but it has stayed cold all summer since the last recharge. I don’t think I need the evaporator yet. ALL I NEED, is the head gasket, front timing cover, wiring harness, a compressor, and a sender unit for the overflow cooling tank.

I thought the smell might be the "fresh air" filters that are a pain to replace. Nothing like the evaporator, but not all that simple either, considering what a silly little things they are. From pictures I've seen from the forums, it seems those filters could easily get wet in under the wipers. I thought maybe it was wet old smelly filters, like old wet dirty socks.

My filters were replaced a while ago, but I don't think it was really all the recently. It was back in the days when I went to the dealer. At least they said they did it, but who really knows what they did. Maybe they didn't even know how to do it, considering how little they knew about adjusting my vacuum modulator on the transmission.

My Indy doesn’t do anything unless I specifically ask for it or it is obviously broken and a safety hazard, so they certainly have not touched those filters. I think I need some filters to see if the smell goes away.

ksing44

You certainly won't be alone. I bet there are far more partially broken Benzes on the road than Benzes in perfect working condition.

shdoug

I had an idea. I took off the cap on the low side of the AC system and smelled it. Same Band-Aid smell. It's the Polyester oil leaking onto the evaporator, visible in the above pictures, that is creating the smell. Damn!

NorCal124

My apologies for straying away from the topic but on the M103 equipped W124s is the low pressure port the one closest to the brake master cylinder or the one toward the bottom next to the receiver drier?

shdoug

The low pressure is on the largest pipe, which is the cold pipe.

PaulX608

There's no cold pipe in my system at the moment, lol

Still haven't done my evap job. The sale of my house fell through 6 days before settlement. Now my boss is on vacation, and I'm working too much and sleeping very little. I did come up with a temporary fix for my evaporator. Since the leak is on the exposed side, I decided to degrease the area and pack epoxy over the leak with a light vacuum in the system. I know I'll lose 2 or 3 square inches of cooling surface, but it'll better than it is now. Gonna do it this weekend. I'll shoot pics, and let you guys know how it works. Even it it slows the leak to where I need a can a week, It'll be better than it is now. Once we sell and move, I'll tear this SOB apart and fix it right.

shdoug

Hmmm...is the coil made of copper covered with aluminum fins? Some AC coils are. These might be all aluminum. If you get all the oil off first you might have a fighting chance of getting it to stick.

rooney2006

what type of coolant do you use to top off the a/c? r134a right? can that be bought at any random auto parts store? and where do i pour it on a car with an m103 engine? my a/c has been running somewhat warm and i figure it's worth a shot to try more fluid. thanks.

ohlord

Side is always the one with the black cap that is threaded so only the proper fitting on the a/c gas can will fit
ohlord
"GOT CODES?"

PaulX608

This one's all aluminum. Probably why it's failed. I'll definitely show pics. We'll see.

PaulX608

You'll have to check the label uner your hood. AFAIK, M-B went to R134a in '92. Your '91 may use R12 which is only available to liscensed HVAC mechanics and is pretty pricey. If you're not familiar with a/c systems, you should get a friend with expereince to help you the first time.

Rio Z Lander

join my world my heat is stuck on as soon as i get cash i have to do the same thing along with rip my heater out becuz i see no need for it a this point in time