I used the wrong can of 134-A too much oil - PeachParts Mercedes-Benz Forum

Waldo · #1 05-23-2016, 12:24 PM

I have an '82 300CD that I have driven 9 years...unknown mileage, but it has
a really good engine and trans.
The A/C system leaks a bit. I did my usual add to charge. The can had been
in the bunch of cans and after I charged the system when I pulled the hose off
it foamed up with the dread yellow stuff.
The can was marked First Charge. How that got in there I have no idea.

I screwed the pooch here. I'm sure someone in the forum knows how to fix this? Is it terminal? Can it be recovered without pulling the dash?

How do I get rid of all that excess oil. It used to blow 38-40 deg, now it's up
to 60.

The A/C is probably my least understood system. Yep. It was stupid. No
excuses, but now I need a fix..Here in the Arizona territory A/C is a matter
of survival.

Can it be saved?--or do I sell it to someone in Alaska?

Thanks again.

WD

leathermang · #2 05-23-2016, 12:33 PM

check out the ac threads on my signature.
pretty much need to take the system apart and flush... then measure the amount of oil put back in...

jay_bob · #3 05-23-2016, 12:45 PM

Yup. Just been through this on my 210 after the compressor nuked itself.

At least you have a 123, with serial flow evaporator and condenser, which can be flushed. Later models went to a parallel flow type condenser and evaporator, which can not be flushed. You can get to the evaporator coil ends at the expansion valve under the dash without having to tear the whole dash apart. Just be careful, the flush will spray everywhere...set up a good containment.

You should replace the following parts on principle, they are inexpensive:
Receiver dryer and sensors
Expansion valve

While you are in there plan on replacing every o-ring in the system (HF has a universal green o-ring kit for $10). And when you have it back together, be sure to pressure test with dry gas before pulling vacuum. If you have a leak and you just pull vacuum then it will draw in moisture and ruin your brand new dryer.

If your system was working well except it had a slow leak, chances are good you will find the source of the leak in your work on the o-rings. Unless the compressor has a shaft seal or (in the case of an R4) case half o-ring has blown. But usually those are catastrophic and it won't hold charge at all.

If you find out the compressor is bad I highly recommend the Roll Guy Sanden retrofit. I have been there before, don't waste your money on a replacement R4, horrible excuse for a compressor.

97 SL320 · #4 05-24-2016, 09:51 PM

You are running R 134A correct? ( not R 143 or R12 ) Any AC shop should be able to recover the freon and that will take oil with it. A technique to remove oil is to charge , recover, separate oil , recharge with "dry freon" then recover. After a few cycles of this most of the oil will be removed then you add the amount the systems calls for ( or there a bouts. )

Waldo · #5 05-25-2016, 01:09 AM

I have surfed this forum for a couple of years and have seen time and time again the help that has been offered in moments of desperation. Now it is my turn..What would I do if you weren't there? Yes I use 134-A. Thanks for the correction.

Leathermang, Jay Bob, 97 SL 320, I seem to remember another one there too.

Thank you so much for the tech info, that takes away my panic. From your advice now there is a plan. Thank you all for helping to save my old Blue Max.

leathermang · #6 05-25-2016, 01:22 AM

Quote:

Originally Posted by 97 SL320

You are running R 134A correct? ( not R 143 or R12 ) Any AC shop should be able to recover the freon and that will take oil with it. A technique to remove oil is to charge , recover, separate oil , recharge with "dry freon" then recover. After a few cycles of this most of the oil will be removed then you add the amount the systems calls for ( or there a bouts. )

That is just not true. The oil accumulates in the lower pockets of the system and pulling with recovery machine does not have the ability to move that oil out....
The MB FSM says to take the system apart... not that many parts... and flush each one... cap, put back together, do the dry pressure test, etc...
Jay Bob had a good post...
Check out the AC thread in my signature...

vstech · #7 05-25-2016, 07:18 AM

Quote:

Originally Posted by leathermang

That is just not true. The oil accumulates in the lower pockets of the system and pulling with recovery machine does not have the ability to move that oil out....
The MB FSM says to take the system apart... not that many parts... and flush each one... cap, put back together, do the dry pressure test, etc...
Jay Bob had a good post...
Check out the AC thread in my signature...

I don't know... But refrigerant does dissolve and carry oil. It's the reason we can't use mineral oil with 134, we have to use an oil that will dissolve in the refrigerant.
So, while simply blowing refrigerant through the system would leave puddles of oil in low spots, a recovery machine should be able to move liquid refrigerant through the system and take with it, most if not all the oil after a few passes. I've never heard of this practice, but it does make sense.
I know my recovery machine has an oil separator, designed for measuring the exact amount of oil removed during a recovery operation, so the exact amount can be returned. I do not know if repeated recoveries would remove all the oil, or clean out a system.
But I do understand how it would.

leathermang · #8 05-25-2016, 09:39 AM

A recovery machine can take out that oil which has been dissolved in the refrigerant in the system... Unless the recovery machine is running a flush liquid repeatedly through the system I am convinced the pockets of oil will not be removed....It is not my impression that that is how they work. We know the recovery machine can not take out the oil in the dryer-receiver or remove the moisture in the jell beads either.. thus it has to be replaced any time the system is exposed to the atmosphere.. either by leak or intentionally by opening the system.
Even on NON low spots ( detached hoses for example ) the MB factory flush machine runs the flush through the system multiple times running it through a filter in the process. Perhaps even two directions....
There are not that many parts in the system. The MB AC FSM gives the basic bottom line trustworthy method. Any other method and you risk having to do it again and replace any affected parts again.
It is your right to chose whatever method you want... as I assume it will be your cost if it has to be repeated or causes further inconvenience ..... the chance that someone who suggests an ' easier' method.... if that does not fix the situation....will put up the money to correct the situation is very slight at best....they have no skin in the game..... so I think it is important to give conservative ( MB FSM for instance ) fail safe advice for some types of systems.... and the AC system is simple but unforgiving if the rules are not followed with regard to what is inside the system.

vstech · #9 05-25-2016, 10:04 AM

All good points!

Also, if the system has been converted from R12 without flushing the components, 134 will NEVER remove mineral oil.

Quote:

Originally Posted by leathermang

A recovery machine can take out that oil which has been dissolved in the refrigerant in the system... Unless the recovery machine is running a flush liquid repeatedly through the system I am convinced the pockets of oil will not be removed....It is not my impression that that is how they work. We know the recovery machine can not take out the oil in the dryer-receiver or remove the moisture in the jell beads either.. thus it has to be replaced any time the system is exposed to the atmosphere.. either by leak or intentionally by opening the system.
Even on NON low spots ( detached hoses for example ) the MB factory flush machine runs the flush through the system multiple times running it through a filter in the process. Perhaps even two directions....
There are not that many parts in the system. The MB AC FSM gives the basic bottom line trustworthy method. Any other method and you risk having to do it again and replace any affected parts again.
It is your right to chose whatever method you want... as I assume it will be your cost if it has to be repeated or causes further inconvenience ..... the chance that someone who suggests an ' easier' method.... if that does not fix the situation....will put up the money to correct the situation is very slight at best....they have no skin in the game..... so I think it is important to give conservative ( MB FSM for instance ) fail safe advice for some types of systems.... and the AC system is simple but unforgiving if the rules are not followed with regard to what is inside the system.

97 SL320 · #10 05-25-2016, 08:29 PM

I never said it will take all of the oil out, just most of it.

The OP overcharged oil by a known quantity and if the system is recovered a few times, much of the oil will come out. Measure what came out, subtract the amount overfilled, add that amount of fresh oil.

leathermang · #11 05-25-2016, 09:13 PM

If he is assuming a known amount of overfill..... I think changing out the receiver dryer is the way to go... and measure the oil in it...

vstech · #12 05-25-2016, 10:29 PM

Quote:

Originally Posted by 97 SL320

I never said it will take all of the oil out, just most of it.

The OP overcharged oil by a known quantity and if the system is recovered a few times, much of the oil will come out. Measure what came out, subtract the amount overfilled, add that amount of fresh oil.

Yes, I agree here. ANY auto shop with a rcovery machine will be able to pull your refrigerant, separate the oil recovered, and tell you how much they got. Since he knows how much oil was added accidentally, the amount recovered can be compared, and everything above the excess he added can be put back and then recharge the ac.

It'll cost more than doing it yourself, but it'll save your bacon here!

leathermang · #13 05-26-2016, 12:41 AM

Quote:

Originally Posted by vstech

Yes, I agree here. ANY auto shop with a recovery machine will be able to pull your refrigerant, separate the oil recovered, and tell you how much they got. Since he knows how much oil was added accidentally, the amount recovered can be compared, and everything above the excess he added can be put back and then recharge the ac.

It'll cost more than doing it yourself, but it'll save your bacon here!

I still think that the oil in the pockets will not be evacuated without some kind of actual flush.... it settled in the pockets because the refrigerant was able to pass it without taking it with it in the stream...think ' eddy '...or 'pool '..... and hooking up a recovery machine will not affect that physics situation... I say that taking oil out by physical removal of the receiver-dryer is probably the most direct and effective and cheapest way.
A recovery machine , if the TXvalve is left in place, can not get a significant flow of refrigerant ... it is not like it can cause turbulence in those pockets ... to stir up and mix it with the refrigerant...

vstech · #14 05-26-2016, 08:19 AM

Quote:

Originally Posted by leathermang

I still think that the oil in the pockets will not be evacuated without some kind of actual flush.... it settled in the pockets because the refrigerant was able to pass it without taking it with it in the stream...think ' eddy '...or 'pool '..... and hooking up a recovery machine will not affect that physics situation... I say that taking oil out by physical removal of the receiver-dryer is probably the most direct and effective and cheapest way.
A recovery machine , if the TXvalve is left in place, can not get a significant flow of refrigerant ... it is not like it can cause turbulence in those pockets ... to stir up and mix it with the refrigerant...

Agreed, but the op just needs SOME oil removed. And the only way to remove the dryer legally is to recover the refrigerant... So...

I promise you... Recovery machines remove oil with the recovery. They pull liquid refrigerant out of the system, and oil is dissolved in the liquid. It's why all true recovery machines have oil separators built in.

leathermang · #15 05-26-2016, 08:41 AM

Quote:

Originally Posted by vstech

Agreed, but the op just needs SOME oil removed. And the only way to remove the dryer legally is to recover the refrigerant... So...

I promise you... Recovery machines remove oil with the recovery. They pull liquid refrigerant out of the system, and oil is dissolved in the liquid. It's why all true recovery machines have oil separators built in.

No one is saying the recovery machines do not take out the oil which is IN suspension in the refrigerant....and remove it from the vehicle ...

Another question is whether the oil holder in a recovery machine can be made empty to start and that recovered and extracted oil is then available for measuring. ? Is it taken out of the refrigerant inside the recovery machine by running the refrigerant though a solvent ? That might preclude an accurate measurement of the oil removed from the system .