buy some r12 or convert to 134a? - PeachParts Mercedes-Benz Forum

TurboSDL · #1 04-25-2009, 04:18 PM

my car has not been converted yet and i noticed on ebay they sell r12 on there so i was wondering if i should buy the r12 or if i should do a 134a conversion? i have ac manifold gauges and a vac pump to evacuate the system (along with alot of other tools) so i was wondering what would be the best route to take? and if i do convert it what do i need to do on my 85 300td td to properly do so? and where are the ports? i know theres one right in your face when you open the hood but where is the other one?

cmbdiesel · #2 04-25-2009, 04:22 PM

I think the most common answer is going to be R-12 if you can get it. The topic of refrigerants gets heated (hehe) here sometimes.

DeliveryValve · #3 04-25-2009, 04:40 PM

Quote:

Originally Posted by TurboSDL

my car has not been converted yet and i noticed on ebay they sell r12 on there so i was wondering if i should buy the r12 or if i should do a 134a conversion? ....

You'll need to get a EPA 609 Certification to legally purchase the R12 refrigerant.

Quote:

Originally Posted by TurboSDL

....and where are the ports? i know theres one right in your face when you open the hood but where is the other one?

The high side port is located behind the alternator.

techguy512 · #4 04-25-2009, 04:45 PM

R-12. Hands down, no question.

TurboSDL · #5 04-25-2009, 04:57 PM

Quote:

Originally Posted by techguy512

R-12. Hands down, no question.

iv charged many cars with my manifold gauges using 134, what do i have to do to charge the system with r12? is it pretty much the same as doing 134? also does the compressor only kick in if i have the r12 in there? thats how it is on all r134a cars iv done...

Palangi · #6 04-25-2009, 05:02 PM

R-12 just ain't that hard to find.

leathermang · #7 04-25-2009, 05:08 PM

If it is still R-12 system you just have to have the correct ends on your guage lines..
If your car has the proper low pressure switch on the reciever dryer ( or close to it ) for safety cut off of the compressor in case of refrigerant leak then it will need to be jumped for insertion ( usually how it is done)... and the safer method...
It is pretty much the same... but do not overfill..... that is the kiss of death for efficiency. Lots of great threads in the archives....
But the bigger question for the long term happiness with your car is why it is needing any refrigerant... do you really need to check for and fix leaks before you put any R12 in ?
That 609 license is an OPEN BOOK test taken over the internet which only costs about $20 the last time I looked.... so that should not be a problem...

NoCalMer · #8 04-25-2009, 05:52 PM

Quote:

Originally Posted by leathermang

If your car has the proper low pressure switch on the reciever dryer ( or close to it ) for safety cut off of the compressor in case of refrigerant leak then it will need to be jumped for insertion ( usually how it is done)... and the safer method...

Would a 85 300D have this? Do you have to jumper it out after pulling a vacuum and refilling?

leathermang · #9 04-25-2009, 07:33 PM

I only pretend to be an expert on the type one MB system...the very simplest....
but that is a normal switch to have for the protection of the compressor... it may or may not be on the actual receiver dryer on your car... someone with one of those cars will probably speak up...
Since it works by cutting off electricity to the compressor when the pressure is low you may want to jump it to fill the system...
You really have a lot more reading and studying to do before you can do this both safely and efficiently..... based on these basic questions.... you do not want to have to start over... or have a really short compressor life, etc..
Did you answer the question about why your system needs refrigerant ? I.E., do you have a leak that needs to be fixed first... if yes, there are specific procedures for flushing, replacing the orings, checking for leaks, etc...

Hit Man X · #10 04-25-2009, 09:25 PM

R12, cost is only marginally higher and leathermang said it about the test, it's a joke.

I tried Freeze 12 in my 300sel last year and the 560, they cool so-so. At idle they really drop off performance.

Ether · #11 04-25-2009, 09:29 PM

Stick with R12. You won't be satisfied with anything else.

I decided to go ahead and take the test this evening and within 30 minutes I had my certificate. Cost me $19.95.

2 of my cars still have R12 so I'm now legit to buy the good stuff to keep them cool.

TOPGUN · #12 04-25-2009, 09:57 PM

Stay with the R-12 system. The fittings on your car are known as 1/4 inch flare. The cost of converting to R134 far exceeds the price of R-12.

leathermang · #13 04-25-2009, 11:01 PM

In defense of ' the test'....
I have taken a lot of government required tests over the years...
Most of them are in the realm of seeing if you are actually able to read and understand the rules and regulations for that particular area of their jurisdiction... You will have those rules available to look at when you are going about your business... and since those things change over the years they just want to know that you have no excuses if they catch you violating the rules...
Like " you gave me a license without checking to see if I could read ".....

Cr from Texas · #14 04-25-2009, 11:08 PM

Fix the leaks first - R12 is too expensive and too unfriendly to the environment to let it escape. There is a procedure in the archieves to put in 2 oz of R22 and then pressurize with nitrogen to find the leaks.

Q. If you evacuate the system, can't you add the required amount of R12 by weight with the car not running? After the required amount is added, do you still need to jump the switch? I thought it would then kick in with the right charge.

leathermang · #15 04-25-2009, 11:14 PM

It is four ounces which is allowed by the EPA of the R22...

You may can add all of it without turning on the compressor... but it might take a long time....and almost certainly would need the help of warm water under the can... if you are up to pressure you do not need to jump the switch....