Air Conditioner System Repair - 300SD - PeachParts Mercedes-Benz Forum

nyko46 · #1 06-05-2011, 03:36 PM

My Mercedes 1982 300 SD is in need of a repair in the air conditioning system which probably I was the cause for make it worse last time that I ad refrigerant.
Previously it was slightly leaking and after a year all refrigerant was gone.
At the end of April 2011 I was adding 134 A to the system but I also put in the system 6 oz of stop leak which caused my system to stop work completely.
I ordered new parts to have it repaired using the DIY method but as I also found that the system still leaking and I do not want to put new parts on it before find and repair the leakage. I have no much idea from where to start checking for leakage and do not know which will be the best and cheaper way to perform this check obtaining the best results. After find the leakage I want to repair it and then go to the next step of clean the system and then start to installing the new parts. I have ordered new Receiver Drier/Accumulator, Expansion Valve, High/Low Pressure Switch, and a kit of Seals.
I also do not know if the stop leak had or not affected my compressor but I know that the compressor should not be cleaned or flushed.
I was informed that to flush the system I will need to use shop compressed air but not informed what is the minimum or maximum PSI required to have it properly flushed. Should I change my compressor oil after the system cleaned and flushed? If leakage is in some area that accept soldering should I solder it? How to flush the evaporator without removing from it's location?
I will need your help in order to accomplish this task and I will be more than happy to hear from you.
I have mine and my wife Mercedes to get this repaired and Texas is very hot during the summer season.
I appreciated your help.
Thanks.

Nyko46

leathermang · #2 06-05-2011, 04:13 PM

Do you have the Delco R-4 compressor... which looks like a hockey puck on steroids ?
That will affect several of the answers....
refresh your screen often to catch the newest answers/ questions...
Where in Texas are you ?

Compressed air is not the best thing to push the flush through the system with.... nitrogen or argon , being DRY, are better..
but with any of them VERY LITTLE pressure is needed... maybe THREE POUNDS... this is not a high pressure flush .. just push it through .... so it can dissolve and take stuff out the other side of the line you are cleaning...
The evaporator is flushed IN PLACE... not the best situation..and certainly one you want to LIMIT the PSI input.. and use DRY gas to push with...
The FSM shows making the OLD Txvalve into a TOOL to do that flushing in place... ( of the evaporator )..
If you have the R-4 you pretty much have NO oil in it.. but it can and should be flushed by hand pouring and turning... not the way the rest of the system is flushed .. but a lower tech cleaning method...
Well, I see you have left the forum without seeing my post...you were still here when I first posted....

nyko46 · #3 06-05-2011, 04:59 PM

Quote:

Originally Posted by leathermang

Do you have the Delco R-4 compressor... which looks like a hockey puck on steroids ?
That will affect several of the answers....
refresh your screen often to catch the newest answers/ questions...
Where in Texas are you ?

Compressed air is not the best thing to push the flush through the system with.... nitrogen or argon , being DRY, are better..
but with any of them VERY LITTLE pressure is needed... maybe THREE POUNDS... this is not a high pressure flush .. just push it through .... so it can dissolve and take stuff out the other side of the line you are cleaning...
The evaporator is flushed IN PLACE... not the best situation..and certainly one you want to LIMIT the PSI input.. and use DRY gas to push with...
The FSM shows making the OLD Txvalve into a TOOL to do that flushing in place... ( of the evaporator )..
If you have the R-4 you pretty much have NO oil in it.. but it can and should be flushed by hand pouring and turning... not the way the rest of the system is flushed .. but a lower tech cleaning method...
Well, I see you have left the forum without seeing my post...you were still here when I first posted....

Sorry,
I did not see your post right the way.
I do have the Delco compressor, that big and havy one.
Your reply, even not getting it complete, is very good and explain very well few issues that I did not know before. If you can continue in this subject will be great. By the way, what is the meaning for FSM and "making the old Txvalve into a TOOL" ?
In Texas I am in the Dallas area near by Rockwall.

leathermang · #4 06-05-2011, 05:02 PM

Have you read the ' sticky ' at the top of the page on AC ?
That is good place to start and should cause you to have more questions...

Clearly you want to open up each segment of the AC system... and clean each one individually...
except the R/dryer as you already know and have ordered... it must be replaced each time the system is opened because the drying agent gets saturated and can not be dried out to be reused...
You will want to find some ' Nylog ' of the right color for your orings/refrigerant... it is just condensed refrigerant oil but is suggested for good tight system when you put the new orings in place...
The chances that you will want to or need to use soldering to fix any leak you have is one in a million... so do not worry about that... unless you blow up the evaporator by putting too much pressure into it...LOLOL

You have TWO mercedes which need AC fixes?