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2001 E320 4matic Wagon, 1999 E320 4-Matic, 1991 190E, S13 SR20DET, Lifted Silverado 2500HD
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9 Posts
Discussion Starter · #1 ·
Hello all! I have been lurking these forums for quite some time. Most of the time, I am able to find my answers by searching or browsing the well-organized stickies, but I am hoping some that have done some AC work can chime in on this subject. First off, I have read the stickies.. over and over, but I have yet to come to a definitive answer on exactly how much oil I should be adding to my AC system and where I should be adding it.

Back story - When I bought my car in 2009, it had a very loud knock that would disappear when the EC button was pressed. Easy diagnosis, AC compressor piston knocking. Since the resolution to this would be replacing the compressor, I decided to ride it out.

About a year and a half ago, AC started to just be cold on the passenger side. Probably the duovalve - I will address this when the AC is working again. About a month after that, the AC stopped working altogether.

Now, after quite some time with just warm air, I have finally saved up enough money to purchase the correct parts to repair. After reading many posts of other members' repairs, I purchased the following parts:

* AC Compressor 7SB16 - Tech Choice Parts
* Expansion Valve - Pelican Parts
* Receiver Drier - Pelican Parts
* Drier to Condenser Hose - Pelican Parts
* New o-ring set - Pelican Parts

My understanding from what I have read (could be wrong), is that when I remove my old compressor, I am supposed to drain and meausure the oil I remove so I can replace it. In addition to that, I am supposed to add additional oil depending on the components replaced.

Oil to be put back into system:

x oz. removed from existing compressor "Fill in the same qty of new compressor oil that was removed"
~.6oz or 20cc "Additional oil filling capacity when replacing refrigerant compressor"
~.6oz or 20cc "Additional oil filling capacity when replacing suction / pressure line"

So... is it safe to say that I replace the same amount of oil that I remove from the compressor PLUS another 1.2 oz to compensate for the "Additional oil filling capacity" for the Drier to Condenser Hose and Replacement of the Compressor?

Also, what if I can't fit all of the fluid in the compressor? Can I just place oil in the drier as well? Does it matter which port I put oil into?

Thanks in advance!
 

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Registered
2001 E320 4matic Wagon, 1999 E320 4-Matic, 1991 190E, S13 SR20DET, Lifted Silverado 2500HD
Joined
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9 Posts
Discussion Starter · #2 ·
Is there any input someone could add to help me out? I know I'm just a lowly lurker with the lowest post count imaginable.. I am a regular on the forums, I just don't post because I usually have more questions than answers. Most answers I find via searching but I just need some clarification.

I really don't want to add the incorrect amount of oil to my AC system (too much or too little).

I just had my blower motor go out today too, so that is more of a pressing issue. I would like to try and tackle the AC and blower motor at the same time.

Thank you
 

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Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
Test blower motor - most likely your blower regulator failed - see eBay for replacement part since MB later updated/new regulator with updated/new blower - so eBay part lets you keep existing blower motor if good.

Don't overstress on the oil at all - your compressor is pre-filled and in the past I have added zero and still have been OK.

Keep the beat !
 

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1997 E300D
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544 Posts
First, your symptoms of cooling only on the passenger side, and later no cooling, sounds like something that would be caused by a leak of 134a. It would be good to determine where the leak is before you dismantle the system. It might be from a part you were planning to leave alone, like an evaporator or condenser. I would fill with 134a with dye and find the leak prior to dis-assembly.

second, on a car as old as yours, the amount of oil found in components is likely to be lower than normal as oil is lost over time due to leaks and repairs where no oil is added. I have converted two R-12 systems to 134a and was not able to find a drop of oil in either system. I think it would be good to blow all oil out of things being left behind and add the correct oil amount in the components as specified by Mercedes. Unfortunately I do not know the figures for your car.
 

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Registered
2001 E320 4matic Wagon, 1999 E320 4-Matic, 1991 190E, S13 SR20DET, Lifted Silverado 2500HD
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9 Posts
Discussion Starter · #5 ·
I replaced the blower motor regulator yesterday, so I have heat again!

I know that my system doesn't have a leak. I had a shop evac the system and they confirmed no leak and also placed the system under vacuum until i replace the compressor.
 

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Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
1st things 1st - glad all is good on the regulator deal... don't sweat on the compressor install - since you have parts in hand, and a decent pictorial - you might consider shopping the right install price from a aircon guy (like from the guys that did the evac) - and call it a day !

That compressor job is very straightforward for a air con shop - like 2hr hr job, maybe hair more on a 4matic jacking around pulling the compressor out..
 

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Registered
2001 E320 4matic Wagon, 1999 E320 4-Matic, 1991 190E, S13 SR20DET, Lifted Silverado 2500HD
Joined
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9 Posts
Discussion Starter · #7 ·
I'm pretty handy with a wrench don't have any qualms about replacing the hardware :) I just know how AC is its own beast and didn't want to add the wrong amout of oil to the system.. I only want to do the job once!
 

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Current 2017 GLE350, 2007 S550, 2002 S430, 1998 ML320 Deceased 74 240D, 92 400E, 97 E420, 13 GLK350
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1,969 Posts
PAG oil levels are for an ML320, which has a similar AC layout to your 98 E320.

R&R for W210 compressor and the post fill values are also attached.

IF the center hub on your compressor cannot be turned by hand (with engine off), then the compressor pistons have locked up. This usually spews particulate downstream of the system. Maybe the drier will pick up the pieces, maybe it will go throughout the condenser to the expansion valve. As a result, you may want to consider replacing the condenser at the same time as when the system is evacuated.
 

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