A/C Suction Line/Hose to Compressor Leak - PeachParts Mercedes-Benz Forum

dstreet · #1 09-17-2009, 09:04 PM

Still hot in New Orleans, so I need cold A/C. Here are the bullets:
-Brand new compressor installed by California mechanic a month ago
-E bay bought car - it's a beauty (85 300CD). When it left CA, a/c worked. Doesn't work now
-Called Mechanic and he suggested I do UV light leak detection test (he used a dye; guess he didn't catch it or it jostled on the trip to N.O.)and I found a leak @ A/C Suction Line/Hose coming to/from Compressor at the flanged point of connection.
-The line runs up the driver's side of car to low pressure freon port.

So, bad sealant/ring?
Loose connection?

Thanks,

Daniel

leathermang · #2 09-17-2009, 10:13 PM

Either bad oring at that junction, loose connection at that junction or the hose fitting to hose bad at that junction or the actual hose near that junction has a crack.

That is one of the problems with dye.... it is not fast and does not come out of all potential leaks and can not be seen when it comes out of some of them..like at the evaporator... he really should have used an electronic detector instead of the dye.....

tangofox007 · #3 09-17-2009, 10:26 PM

Unlike the original compressors that sealed with a pair of ordinary o-rings, the new versions have stepped ports the don't work well with the original hose manifold. There are a number of seal combinations for different vehicles and sometimes the wrong combinations are selected by the installer. Often, that is because the wrong combinations are furnished with the new compressors. In the final analysis, even with the optimum seal combination, a perfect seal on a stepped port compressor is far from guaranteed.

Some additional info:
http://www.peachparts.com/shopforum/showthread.php?t=253794&highlight=napa+compressor+seal

dstreet · #4 09-18-2009, 08:47 AM

Thanks. I've attached a pic using UV light and you can clearly see the dye. Pinhole in the hose perhaps?

#5 09-18-2009, 10:07 AM

The pic is interesting, but does not address the issue of FIXING the leak. Tango is right on top of this. The early compressors used when your car was manufactured used a simple o-ring. Later compressors used a composite seal made of multiple materials requiring a large recess area.

I would be willing to bet that when you pull the manifold loose you will find one of two issues; either the compressor has the larger recesses such that an o-ring will not be compressed OR there is an issue with the bolt and it's threads.

Exploratory surgery is the only reasonable course of action at this point.

Matt L · #6 09-18-2009, 10:08 AM

Looks like it, dstreet.

For future reference, you don't need to use the UV lamp when taking a picture of the dye. The camera flash works better.

dstreet · #7 09-18-2009, 11:47 AM

Thanks guys. No time like the present to learn A/C repair I suppose. With a high pressure system I suppose I'll eventually need a compressor if/when the hose is to be removed to check for proper seals, right?

#8 09-18-2009, 12:42 PM

No you won't need to replace the compressor. You will have to have the charge recovered if there is any left in it. Once empty, disconnect the manifold from the compressor and see what the seal situation is.

leathermang · #9 09-18-2009, 12:47 PM

Follow Larry's plan...

if it IS just pin hole in that hose.....

you may ( if there is enough slack in the routing of that hose ) be able to take that hose and fitting to a local hydraulic hose repair shop and just have them shorten it enough to take out that pin hole.

It is not likely... but no risk to checking it out..

dstreet · #10 09-18-2009, 05:29 PM

Will do. Much appreciation and thanks once again.

Daniel