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300SD 1984
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58 Posts
Discussion Starter #1
Dear all experts:

My Benz is a 1984 300SD
I have changed condenser in the the a/c system
to a parallel flow condenser.
I have filled it with two 13 oz cans of 134a
At engine idling, the a/c air coming out of the vent measures 64 degrees.
Is that it ?

I think it was colder before the condenser was changed.

Does anyone have the same situation with 134a ?
With the air not less than 60 degress ?
 

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Administratoris Emeritus
2021 SL770
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46,428 Posts
^ Yup, R134 systems require larger capacity than your system provides.
 

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300SD 1984
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58 Posts
Discussion Starter #4
Add capacity

Would an additional parallel flow condenser
be the answer ?

I have seen a picture of 2 condeners hooked up
in BMW a/c system.

Would 2 condensers resolve the issue and
decrease the a/c temperature from 65 to 40 degrees ?
 

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Banned
99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
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Not cheaping out and Not putting crappy R-134a in the system would have been the answer. I'm surprised that you got it down to 64. That is actually very good for R-134a. You need to convert back to R12 if you want real cooling capacity.
 

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2006 B 200 .....& Audi A6..
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I would think it's nearly impossible to find R-12 and environmentally a poor choice if located.
An A/C tech should be able to check your high and low sides(pressure) and give some recommendations using R-134.
 

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500SE AMG, E350 4matic, GL 450
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R134a is going to be going the way of R12 soon. From what I have read a new refrigerant (think it is called R744) is on its way. I cant remember exactly, but it seems like by 2011 new vehicles in Europe will have it. It is carbon dioxide based. Once again-can't remember exactly what the article said so I might be wrong about the CO2 part.
 

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2006 B 200 .....& Audi A6..
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So far nothing is as efficient as the old R 12 but I would hope that 64 F can be improved on.
All of our newer cars have R 134a and temps in the 50's F at the exit vent so let's hope some mods will help for the time being, when using the older systems with the newer R 134a.
 

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99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
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I would think it's nearly impossible to find R-12 and environmentally a poor choice if located.
An A/C tech should be able to check your high and low sides(pressure) and give some recommendations using R-134.
R12 is NOT hard to find. Anyone can order it online or locate it at select A/C shops around the country. It won't harm the enviroment one bit if you don't release it into the air and have an A/C system that works correctly (not leaking). I just fixed my A/C system after figuring out that some idiot topped it off with R-134a and mixed the two. Guess what went back in? Brand new R12 that I purchased and resold to my mechanic for $0.01. These older cars were NOT designed to run of R-134a. No matter how much of a charge you put in there, the air isn't going to be any cooler. You would have to install a new large a$$ condensor and new high-output cooling fans to make a W126 go down below 60 degrees on R-134a. That is just not realisitic, way too time consuming and really expensive. R-12 isn't that expensive and NO, its not hard to find. Anyone who says its hard to find has never looked.
 

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R12 is NOT hard to find. Anyone can order it online or locate it at select A/C shops around the country. It won't harm the enviroment one bit if you don't release it into the air and have an A/C system that works correctly (not leaking). I just fixed my A/C system after figuring out that some idiot topped it off with R-134a and mixed the two. Guess what went back in? Brand new R12 that I purchased and resold to my mechanic for $0.01. These older cars were NOT designed to run of R-134a. No matter how much of a charge you put in there, the air isn't going to be any cooler. You would have to install a new large a$$ condensor and new high-output cooling fans to make a W126 go down below 60 degrees on R-134a. That is just not realisitic, way too time consuming and really expensive. R-12 isn't that expensive and NO, its not hard to find. Anyone who says its hard to find has never looked.
It looks like use of R12 by uncertified individuals is illegal:
A/C Refrigerant Rules
The prices I saw were between $250 to $450 a case.
 

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2006 B 200 .....& Audi A6..
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It looks like use of R12 by uncertified individuals is illegal:
A/C Refrigerant Rules
The prices I saw were between $250 to $450 a case.
In some locations R 12 is very hard to find.
Environmentally it's the worst choice and older systems can be modified to work with R 134a.
Your system has already lost the original R 12 due to leaks and no system is perfect and will eventually leak.
R 12 kills the ozone layer :eek: and is being banned everywhere for a good reason.
Why kill the planet faster than we already are??:mad:
 

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2003 Mercedes Benz E500
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Some vehicle manufacturers...

actually produce a full retro-fit kit, including a new evaporator, expansion valve, etc.

I did the conversion on a 240 series Volvo with the above, and it worked reasonably well; however, I somehow doubt the DB has this for a 24 year old car.

I concur with Derek: "So far nothing is as efficient as the old R 12 but I would hope that 64 F can be improved on." You should be talking with an A/C professional to see what can be done.

R-12 is still certainly still available, though pricey, if you are licensed to buy it, which I am; however, your system needs to be in top notch condition... otherwise you will be wasting a good bit of money and sending the R-12 into the atmosphere, which is not a good thing.

Good luck,

JR
 

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99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
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It looks like use of R12 by uncertified individuals is illegal:
A/C Refrigerant Rules
The prices I saw were between $250 to $450 a case.
You forgot to mention the all-important EPA sub-section that states that individuals who are not licenced are allowed to purchased R-12 with 'intent to resell to an EPA licenced' individual. That is exactly what I have done. I purchased it online, then resold it to my EPA licenced mechanic. My mechanic was the one who put it in the car for me, as I watched. Perfectly legal and $100's cheaper.
 

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99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
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In some locations R 12 is very hard to find.
Environmentally it's the worst choice and older systems can be modified to work with R 134a.
Your system has already lost the original R 12 due to leaks and no system is perfect and will eventually leak.
R 12 kills the ozone layer :eek: and is being banned everywhere for a good reason.
Why kill the planet faster than we already are??:mad:
Your car's engine running is killing the environment too, so you better not use it anymore. Do you really think one vehicle with a sealed R-12 system is going to kill the ozone layer? Come on. What do you think happens in junk yards when old W126's come in after a rear end crash? The R-12 line gets cut and out it goes. It happens all the time. A sealed, working A/C system is the least of the ozone's worries.
 

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1985 300 SD
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Pardon me but, BULL!

Cooling isn't determined by "how much of a charge you put in there". More than the system's capacity does not help, it hurts.

Also, the other person's system is OVERCHARGED IF HE PUT 26 OUNCES IN. Mercedes 1985 300SD calls for FOURTEEN OUNCES IF THE SYSTEM HAS BEEN COMPLETELY FLUSHED AND HAS NO OIL WHATSOEVER.

So, he has displaced the space normally meant for Freon and instead over-filled it with oil.
That leaves no room for the amount of Freon the system needs to cool properly.

R134a can be used very successfully in these cars.

If you are guessing about all of this, you are hurting others as they may think that you really know of which you speak. I am not intending to hurt you but, come on, help and not hurt.

Joe


R12 is NOT hard to find. Anyone can order it online or locate it at select A/C shops around the country. It won't harm the enviroment one bit if you don't release it into the air and have an A/C system that works correctly (not leaking). I just fixed my A/C system after figuring out that some idiot topped it off with R-134a and mixed the two. Guess what went back in? Brand new R12 that I purchased and resold to my mechanic for $0.01. These older cars were NOT designed to run of R-134a. No matter how much of a charge you put in there, the air isn't going to be any cooler. You would have to install a new large a$$ condensor and new high-output cooling fans to make a W126 go down below 60 degrees on R-134a. That is just not realisitic, way too time consuming and really expensive. R-12 isn't that expensive and NO, its not hard to find. Anyone who says its hard to find has never looked.
 

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Registered
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Dear all experts:

My Benz is a 1984 300SD
I have changed condenser in the the a/c system
to a parallel flow condenser.
I have filled it with two 13 oz cans of 134a
At engine idling, the a/c air coming out of the vent measures 64 degrees.
Is that it ?

I think it was colder before the condenser was changed.

Does anyone have the same situation with 134a ?
With the air not less than 60 degress ?
Yes, I also have this problem. I have a 1981 300SD and I just had them convert it over to 134a from R-12. The reason was that they had put in Freeze-12, some hot shot and it might have been the mix but the compressor started making a noise so I shut it off and ordered all new parts from Performance Products. R-4 compressor,dryer, switches, expansion valve etc. They failed to replace the expansion valve (see my post) and all I get is 57.2 air from the vents. With R134a on a 80 degree ambient temp. low side should be around 30 psi and high 175 to 200. There should be a 30 degree difference between the outside air and the vent. I am taking mine back to a different shop and will let you know how it turns out. I live near Springfield, MO and could not find any R-12 and my 30lb drum was out. Hang in there we will overcome.
 

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99 Merc S420 (80k Mi) 07 Lexus LS460 (21k Miles)
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Pardon me but, BULL!

Cooling isn't determined by "how much of a charge you put in there". More than the system's capacity does not help, it hurts.

Also, the other person's system is OVERCHARGED IF HE PUT 26 OUNCES IN. Mercedes 1985 300SD calls for FOURTEEN OUNCES IF THE SYSTEM HAS BEEN COMPLETELY FLUSHED AND HAS NO OIL WHATSOEVER.

So, he has displaced the space normally meant for Freon and instead over-filled it with oil.
That leaves no room for the amount of Freon the system needs to cool properly.

R134a can be used very successfully in these cars.

If you are guessing about all of this, you are hurting others as they may think that you really know of which you speak. I am not intending to hurt you but, come on, help and not hurt.

Joe
You didn't disagree with anything (besides the R134a part) that I said, yet you quoted me?

R-134a CANNOT acheive the same low temp that R-12 can in these cars. There is no disputing that fact. I have done my own car on car comparison. There is between a 8-12 degree temp different between the two refridgerents in classic Mercedes that were factory designed and factory tested to run on R-12. That also doesn't take into account that R-134a is very corrosive. It is made of smaller molecules that will easily leak from the smallest of small holes in your system. These systems can rot from the inside out under long term R-134a usage. If you want your car to work correctly, then there is NO substitute for the real R-12 deal. An 8-12 degree lower air temp is a significant difference in my book. It's worth every penny of the low price that I paid to buy the R-12 wholesale online.
 
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