I am the new owner of a used 87 300D i am fixing up for my wife.
Hopefully after this weekend the AC will be running.
However, I have read several ominous posts already about the Cars air conditioning system which dismay me. One was about the evaporator being suspect and a 20 hour replacement job. But I see the evaporator sitting right there in the driver side wheel well. The other was the AC system's complex electrical relays.
Is the Cars A.C. system really that complicated? Why would they make it that way? What should I be ready for this weekend? I have resurrected 5 or 6 pre 1985 import AC systems and to me the problem usually was found either in the Compressor or Hi Side Hose.
I still believe that any compressor circa 1980, especially on the W123, series usually has worn seals. I am happy to hear that the W124 300D 's compressor, even though 1987, does not have this problem.
With only average AC experience, is there a 60% chance my AC will run this weekend? Here in HUMID South Jersey cars require AC before diesel to move. Or is more probable that this weekend will be just a fact finding mission....







http://mywebpages.comcast.net/snow7ice/BENZ.html

The 15-20 hour flat rate and reported times for evap removal and replacement were for the 123.... generally 1980 -1984....
So maybe they had corrected this situation by 1987.... don't know...
Usually the evaporator does not need servicing from a leaking perspective... but it might be nice given the age if you can look and clean the upstream fins.... since air does have to transverse that area in order to cool you.
If your car has the same general system.... block valve next to the evaporator.... then you may want to install a new one... about $35 on our cars.... just on principle...
You did not say why yours is not working... or what you have done to it.... and I do not have a manual for your car ....
Do YOU have a MB factory service manual for your AC system to look at ? More specifically to read any warnings or instructions concerning flushing , etc ?
If not... I do not give you a 50 percent chance of getting it going properly THIS weekend.... Weekends are much harder for acquiring parts down here... so any two days not a weekend ups the chances for success within the time frame considered...

What AC working tools do you own or have available ?

Leathermang,

I have to disagree with you on this one. The 15 to 20 hours is for the 300E (124 body) evaporators. These are the cars with the problem a/c systems. The 123 chassis doesn't normally have evaporator problems unless its really old.

The evaporator problems started coming up when MB cut some corners and used cheaper materials.

BTW I think its more like 8 hours to R&R the dash on a 123.

__________________
84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)

Carrameow is working on a W124. And yes, the evaporator is suspect. I had a 1987 300E on which I spent $8000 in repairs in just 2 years (major A/C work 3 times) and still sold it with a broken air conditioner because the evaporator spring a leak.

Yes, it is a long job to change an evaporator (the part behind the dash board) on a W124 and I refused to do it. The procedure is pretty well detailed in at least a couple threads on this board. Just search for "300E evaporator."

Carrameow, much of that added complexity is to protect the serpentine belt. On the OM616/7 and earlier engines, if the compressor locked up then it would shred the A/C belt and you'd keep rolling along with no problem. But on the OM603 and later engines, if the compressor locks up then you can loose the one and only serpentine belt and you're stranded. So they put the electronics in to detect a compressor lockup and release the clutch.

Another problem with the car in question is that the Nippondenso compressor has teflon coated pistons which spread "black death" throughout the system when the compressor fails. Go to aircondition.com and look up black death. Not pretty at all, and not easy to get rid of. Sorry, but I'm not optimistic that you'll get the A/C working in just one weekend unless it is something as simple as a leaking schraeder valve.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

The driver side wheel well has the oil cooler. The evaporator is buried by the firewall under the dash. Windshield wiper mechanism comes out too.

Regards,

__________________
Brian Toscano

Please tell me he didn't think the oil cooler was the A/C evaporator.....

Eric, I did not mean to imply the 123 had a reputation for having problems with the evaporator.... but a few on this forum have had problems.... and I think it was just recently that the flat rate manual... and several peoples experience was a shocking 15 hours plus..... a search would bring it up...

Tim, rack it up to optimist thinking....

and I know about thermodynamics and all that cr__ and I got the evaporator/condenser terminilogy mixed up and somehow thought he oil cooler was.... I feel like a moron..somedays my brain just doeant work, some days its great...

Carrameow,

Don't get too flustered before you even get started. Yes, the evaporator is a trouble spot in these cars, but just because the AC is not working does not mean that this is your problem. There are many other things that could be wrong.

You should start by determining if your system has refrigerant. Hook up the guages and see if you have about 80 to 85 pounds static pressure. If not, then yes you need to start looking for the leak, but don't condemn the evaporator without proper diagnosis. If you do have good static pressure then see if you can get the clutch to kick in. A slipping belt will shut the compressor off. You should see that the belt is tight and not oily.

Check pressures, then we can take the next step.

Don't give up and don't jump to conclusions.

Best of luck,

Thanks Larry. W124 A/C is still a sore subject with me and I tend to get emotional.

Carrameow, do what he said.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Rick, I don't blame you .... that $8000 would have bought 16... yes SIXTEEN perfessor Leaky's..... AMAZING...

and the system came to life! I was intimidated by the complexity of the car, I think and all the things I heard abou the evaporator and solenoid protection on the Serpentine belt.
By the way, those new cans with the insertion nozzle right on them really make AC charging easy. They are fool proof and leak proof .The old metal can taps always leaked and resulted in terrible charge quality and you always had to use Hot water for some reason to pump the Freon in.

OOPS

Carrameow,

So the system had been converted to 134? How well does it work? In your climate you might do okay with it.

Good luck,