A/C hose leak W140
 

I had a compressor oil leak at the lower condenser fitting on my 96 S500. I tried tightening the fitting, but that made the leak worse. We evacuated the system, replaced the seal using a similar size seal out of an assortment and after about a week the system lost charge and stopped working. We then evacuated the system again and replaced the seal using the replacement seal from the Mercedes dealer. We recharged the system using leak detection dye and in two days the system lost charge and stopped working again. Inspection with a black light shows that the lower condenser fitting is leaking, we dont find any other leaks. The parts man at the Mercedes dealer told me that the hose that goes from the compressor to the lower condenser fitting has been problematic. He also recommends replacing the drier. Has anyone else had problems with this hose? Is it really necessary to replace the drier? Is it possible that I damaged the condenser fitting when I tightened it? Any advise will be greatly appreciated. Thank you.

Anyone?

You should always replace the dryer when you have opened an a/c sytem-period!
R12 systems are much more moisture forgiving than R134a. It's either a bad hose or a bad condensor.


Michael

Overtightening an AC fitting can damage it, they are aluminum and easily distorted. I have on at the same location on the TE that may require replacing the condenser as I cannot unscrew it and I'm pretty sure it leaks....

Verify that it is the fitting and not the hose, though -- a hose leak at the seal between hose and fitting may look excatly like a bad fitting!

If the fitting is round, the faces the seal touches are smooth, and it screws together smoothly, its not likely to leak.

R134a systems charged with poly ether oils absorb water from the air quite badly, so you end up with excessive water in them when the leak down. This will often cause the absorbant pack in the drier to burst, and the resultant flood of abrasive crud clogs the condensor and evaporator and grinds the compressor up. New receiver/driers are cheap compared to the other parts....

Peter

I have replaced an A/C hose on my S320. This hose is part tubing/hose that rest on the left fender. The bottom of the tubing was rusted out, you will need to pull out the insulation to view the damage tubing. This is an expansive hose, a shop that repair hydraulic hose replaced the rust part for less than $25.

If your have leak due to rust like mine, you will need to replace the dyer.

Jack

The same thing happened to me on my 140, the lower condensor fitting/valve was leaking. It is a hairline crack in the thread area of the fitting where the valve screws into the condensor. Replacing the seal will not help, what I did is put two seals in there. One in the normal position, and one just a bit smaller that sealed it at the bottom of the valve where it comes in contact with the inside of the fitting. This fixed the problem and it has been working for 3 years (new owner says working fine, I sold the car). Just go to the parts store and get the r134 seals and it match the size to the bottom of the valve, it has to be the exact size to work. This was much cheaper than replacing the condensor. ($2) Good luck!
Brian

oh, my valve was damaged in the fitting because someone that was checking my ac system used those gauges that plug in, when they pulled the connector off they pulled it at an angle, which moved the valve in the fitting just enough to crack it. Of course I went and tried to tighten it which made the leak worse, but putting that additional seal in there fixed it.
Brian