amoffitt

Update: The A/C started working by itself last night. I turned the car on and pulled it out of the garage and it started working like normal. I noticed the terrible smell that comes from the vents that is talked about occasionally and knew that the A/C was actually working. I did not rev the engine to 2K or anything like that. I am not sure whats going on.

Boston M Benz

I have the same problem 2010 C300 4matic sport. I find that i have to leave the AC on at all times, I just keep it on low and use the thermostat to change temp. When it works, it works great. Sometimes I have to restart my car at a stop light to get the AC going when its hot. very annoying

amoffitt

You know, this is still a problem that my car has. I guess I kind of forgot about it and I just treat it as a normal thing now.

HBguy

Normally, a clutch on the A/C compressor will cycle on and off while the A/C is on. It does so by refrigerant ("freon") temperature or pressure. It sounds like the clutch might be sticking if the diagnosis of needing to shut off the engine is right, and depending on the system, you might only need to replace the clutch. I don't think people do that anymore because price wise its a little more to just replace the clutch/compressor together and sometimes you have to because of how they might be built- which might be why the dealer told the other guy the 'compressor is going out'...because its extremely rare for the compressor to go bad. If the refrigerant charge is OK, then shop around for a compressor swap. I suggest taking it to a shop that specifically works on A/Cs for vehicles. Even if you get ripped off, you'll probably get a better warranty and better qualified technicians.

amoffitt

I am going to keep running it like it is. I guess I forgot about this post since it has been so long. I do not drive this one too often so when I do use it, it tends to function like it should.

HBguy

That's a good call if you can work with it. Automotive A/C is not as simple as most HVAC/R people or automotive people think, unless the car is a 'classic'. Shops nowadays rarely seem to try to actually figure things out beyond a OBDII scan.

amoffitt

It is interesting because I had to fix two of my 124 cars and both had issues with A/C Compressors. I found a place that rebuilt compressors and sent it off to them. They did good work and I put the compressors back in after they were done and went back to working. Although keep in mind, one was a 1988 and the other was a 1993 model.

HBguy

First, my apologies for the childish rhetoric in my comments from 2016. In re-reading it now, I owe everyone that. What was the diagnosis on the compressors? I might have said this in this thread or not, not sure, but it's almost always the clutch that goes out, not the compressor itself. With some systems, the clutch is a part of the compressor, and with most shops, they'll just replace both since it makes more sense regarding price and ease of install/labor hours and potential warranty issues.

amoffitt

No worries for 2016 on my part.

Here is the data I have from my cars:

1993 Mercedes 300D - Leak test with automotive HVAC machine showed a leak. I was not able to track it down so I charged the system up anyway. At that point, the compressor would not spin. I did notice a bit of green residue around the front of the compressor, near the pully area. I was able to free it up by more or less using a wrench to get it going. The car blew cold air for about 30 mins and then no more cold air was blowing. When I put two and two together, I am guessing the previous owner had a freon leak. To try to fix this they put the sealant stuff in there and potentially caused the compressor to lock up. On this one, I do not think we put the fluorescent leak detection stuff into the system. I took I had a spare compressor in the garage that came off of a R12 car, I sent that one off for rebuild/cleaning. Once I got it back it looked brand new and spotless. That compressor went into this car. Vacuum tested it with no leaks. I filled it up with exact oil and freon per spec and it works nicely now.

1988 Mercedes 260E - Leak test with automotive HVAC machine showed a leak. I put the R12 to R134a conversion kit on this car. Took a wild guess since the compressor was leaking in the 300D and figured that might be the same problem this car has. Both are the same part. So I took the compressor off on this car and sent it in for a rebuild/cleaning. In the meantime, the compressor that was already rebuilt and back to me from the 300D, I put in this car. Vacuum tested and it passed, no leak was detected anymore. I charged it up to spec with oil and freon and has been working nicely since. The only complaint I have on this car is that the center vents do not blow air. The actuator is faulty but I do not want to remove the dash to fix that problem. I did not replace any seals, o-rings or anything when I did the conversion. Some people say to but I did not.There might have been other work done to this HVAC system on this car but I forget since I have had it a little longer.

The compressor that came out of this car went off for the same rebuild and now it currently sits on a shelf in my garage in the box. It looks brand new and clean.

2009 Mercedes C350 - I haven't done anything with this car. When I use it, the A/C works. If it does not, I just rev it a little bit until the compressor kicks in.

The Rebuilds - I did not want to put a brand new compressor in because I figured it would not be the quality that these older cars had in them. I chose to have them rebuild. I was not able to find anyone locally in Texas to do this type of work. I looked around and found a rebuild shop in Nevada. All 3 of the compressors I had (Spare R12 Unit, 300D, 260E) were shipped to them for rebuilds. I shipped them one at a time almost in like a rotation so I could test out one coming back and make sure I was happy with the work before spending money on another one being rebuilt. I can find the shop's info if anyone needs it.

Side note - The only annoyance I have with any of this is that the compressor that is in the 300D, when it is in use seems to drop fuel efficiency more than I would have thought it would. I could probably get around that by putting a newer compressor on that put less resistance on the belt but I prefer to keep it this way since it works.

Sorry for the long post but that covers most everything.

Boston M Benz

today it was almost 100 degrees out and i could not get the AC to blow cold, it was blowing slightly cooler air, not hot air. Even after turning the car off and on it wouldn't work. Yesterday was nearly as hot and the AC worked great. I'm guessing it has something to do when its hot outside, when its below 80 degrees out it seems to always works or restarting the car will do the trick. Just sucks b/c today when I really needed it, it didn't work. there are only a couple days a year when it is this hot out in New England (Massachusetts) and I dont really want to put $1000 into the 15 year old c300 sport 4matic even if there is only 88k on it. I'm thinking about selling it and going back to my Camry. Toyota, especially Camrys, have mastered the art of making cars works with just regular maintenance. My 2009 camry runs like new, everything works except there is an O2 sensor CEL but in my state I can still get an inspection sticker with CEL for emissions over 15 years old. I've had my 2010 c300 sport for 3 years and ive already have to change an ignition coil, fix a broken drivers side door handle (what a job that was), and had to replace the secondary air pump. I have a bad feeling older Mercedes are a lot more work than I want to do. We'll see.

Boston M Benz

Is there a relay for the AC in these W204 or only a fuse? Ive tried to find out but I was only able to locate the fuse. Anyone know?